{"id":3177,"date":"2026-04-15T10:33:57","date_gmt":"2026-04-15T02:33:57","guid":{"rendered":"https:\/\/www.c-adtech.com\/?p=3177"},"modified":"2026-04-15T15:24:01","modified_gmt":"2026-04-15T07:24:01","slug":"aluminum-melt-treatment-fluxes-degassing-and-drossing-specifications","status":"publish","type":"post","link":"https:\/\/www.c-adtech.com\/ru\/aluminum-melt-treatment-fluxes-degassing-and-drossing-specifications\/","title":{"rendered":"\u0424\u043b\u044e\u0441\u044b \u0434\u043b\u044f \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0438 \u0430\u043b\u044e\u043c\u0438\u043d\u0438\u0435\u0432\u044b\u0445 \u0440\u0430\u0441\u043f\u043b\u0430\u0432\u043e\u0432: \u0422\u0435\u0445\u043d\u0438\u0447\u0435\u0441\u043a\u0438\u0435 \u0445\u0430\u0440\u0430\u043a\u0442\u0435\u0440\u0438\u0441\u0442\u0438\u043a\u0438 \u0434\u0435\u0433\u0430\u0437\u0430\u0446\u0438\u0438 \u0438 \u0434\u0440\u043e\u0441\u0441\u0435\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f"},"content":{"rendered":"

Aluminum melt treatment fluxes are inorganic salt-based or chemical compound formulations applied to molten aluminum at temperatures of 680\u2013780\u00b0C to perform three critical metallurgical functions: degassing (removing dissolved hydrogen gas that causes porosity), drossing (separating and removing non-metallic inclusions and oxide films from the melt surface), and furnace wall cleaning (dissolving and removing sintered oxide buildups from furnace linings) \u2014 with AdTech’s flux product range covering granular degassing flux<\/a>, powdered drossing flux<\/a>, covering flux, and refining flux<\/a> in formulations based on chloride-fluoride salt systems, achieving hydrogen content reductions of 50\u201380% and dross metal loss reductions of 40\u201360% when applied correctly in aluminum foundry and smelting operations.<\/p>\n

If your project requires the use of Aluminum Melt Treatment Fluxes, you can contact us<\/a>\u00a0for a free quote.<\/span><\/p>\n

At AdTech, we formulate, manufacture, and supply aluminum melt treatment fluxes to foundries, die casting operations, secondary aluminum smelters, and continuous casting facilities on a global basis. The metallurgical challenges our customers face are consistent across geographies: excessive porosity in castings traced to dissolved hydrogen, unacceptably high dross metal loss consuming valuable aluminum, furnace productivity losses from oxide buildup on walls and hearths, and inconsistent casting mechanical properties linked to inadequate inclusion removal. Flux treatment, when properly specified and applied, addresses all of these challenges simultaneously.<\/p>\n

\"Aluminum
Aluminum Flux<\/figcaption><\/figure>\n

The Metallurgical Case for Aluminum Melt Treatment: Understanding Hydrogen and Inclusion Problems<\/h2>\n

Molten aluminum presents two fundamental quality challenges that flux treatment addresses directly. Understanding why these problems exist \u2014 not just that they exist \u2014 is essential for selecting and applying fluxes effectively.<\/p>\n

The Hydrogen Solubility Problem<\/h3>\n

Aluminum has an unusual and problematic relationship with hydrogen. At room temperature, solid aluminum dissolves almost no hydrogen (approximately 0.036 ml H\u2082 per 100g Al at the melting point solid side). At its melting point liquid state, aluminum dissolves approximately 0.69 ml H\u2082 per 100g Al \u2014 a 20-fold increase in solubility across the solid-liquid transition.<\/p>\n

This dramatic solubility change has severe practical consequences during casting. As the liquid aluminum solidifies in the mould, hydrogen solubility drops precipitously. The excess dissolved hydrogen cannot remain in solution and must leave the metal. If it cannot escape through the solidifying metal surface quickly enough (which in most casting situations it cannot, due to rapid solidification), it forms gas bubbles that become trapped porosity in the solidified casting.<\/p>\n

The hydrogen enters the aluminum melt from multiple sources: atmospheric moisture (H\u2082O reacts with molten aluminum: 2Al + 3H\u2082O \u2192 Al\u2082O\u2083 + 3H\u2082), wet or contaminated scrap (organic residues, surface moisture, oil contamination), wet refractory linings and furnace tools, humid combustion gases in gas-fired furnaces, and wet alloy additions.<\/p>\n

The quantitative target for most aluminum casting applications is a dissolved hydrogen content below 0.10\u20130.15 ml H\u2082 per 100g Al before casting. For critical aerospace or pressure-tight applications, the target may be below 0.08 ml\/100g. Untreated secondary aluminum melts commonly contain 0.30\u20130.60 ml\/100g \u2014 three to six times the acceptable level.<\/p>\n

The Inclusion and Oxide Film Problem<\/h3>\n

Simultaneously with the hydrogen problem, molten aluminum accumulates non-metallic inclusions that degrade casting quality:<\/p>\n

Surface oxide films (Al\u2082O\u2083 bifilms):<\/strong>\u00a0Form instantly when the metal surface contacts air. Turbulence folds these films into the melt body, creating double-layer oxide inclusions (bifilms) with an unbonded internal surface that acts as a pre-existing crack in the solidified casting.<\/p>\n

Spinels (MgAl\u2082O\u2084):<\/strong>\u00a0Form in magnesium-bearing alloys (including A356) from the reaction of magnesium with aluminum oxide. Spinel inclusions are harder and more stable than Al\u2082O\u2083, making them particularly damaging to machining operations.<\/p>\n

Alkali metal compounds:<\/strong>\u00a0Sodium and calcium from scrap contamination or flux carry-over form aluminum-alkali compounds that reduce surface tension and increase hydrogen absorption, compounding the porosity problem.<\/p>\n

Refractory fragments:<\/strong>\u00a0Physical wear particles from ladle linings, furnace walls, and tools that contaminate the melt stream.<\/p>\n

Effective flux treatment addresses both the hydrogen problem (through degassing flux application) and the inclusion problem (through drossing and refining flux application), working synergistically to produce clean, low-hydrogen metal ready for casting or filtration.<\/p>\n

Classification of Aluminum Melt Treatment Fluxes: Types, Functions, and Chemistry<\/h2>\n

Aluminum melt treatment fluxes are not a single product \u2014 they are a family of chemically distinct formulations, each designed to perform a specific metallurgical function. Using the wrong flux type for a given function produces poor results and may introduce new problems.<\/p>\n

Primary Flux Categories<\/h3>\n
\n\n\n\n\n\n\n\n\n\n\n\n
Flux Type<\/th>\nPrimary Function<\/th>\nSecondary Functions<\/th>\nPhysical Form<\/th>\nTypical Application<\/th>\n<\/tr>\n<\/thead>\n
Degassing flux<\/td>\nHydrogen removal<\/td>\nSome inclusion flotation<\/td>\nGranular or powder<\/td>\nLance injection into melt body<\/td>\n<\/tr>\n
Drossing flux<\/td>\nDross separation and fluidity<\/td>\nMetal recovery from dross<\/td>\nPowder or granular<\/td>\nSurface application and stirring<\/td>\n<\/tr>\n
Covering flux<\/td>\nMelt surface protection<\/td>\nHydrogen barrier<\/td>\nGranular<\/td>\nSurface blanket layer<\/td>\n<\/tr>\n
Refining flux<\/td>\nInclusion removal and coagulation<\/td>\nAlkali removal<\/td>\nPowder or tablet<\/td>\nInjection or stirring<\/td>\n<\/tr>\n
Cleaning flux<\/td>\nFurnace wall cleaning<\/td>\nHearth cleaning<\/td>\nGranular<\/td>\nDirect application to furnace surfaces<\/td>\n<\/tr>\n
Combined (multipurpose) flux<\/td>\nMultiple simultaneous functions<\/td>\nVarious<\/td>\nPowder or granular<\/td>\nGeneral melt treatment<\/td>\n<\/tr>\n
Salt-free \/ low-chloride flux<\/td>\nDegassing (environmentally optimized)<\/td>\nReduced emission<\/td>\nPowder or tablet<\/td>\nEnvironmentally regulated operations<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Flux Selection Decision Framework<\/h3>\n

Flux type selection depends on the specific metallurgical objective:<\/p>\n

Primary objective: Porosity reduction<\/strong>\u00a0\u2192 Specify degassing flux; apply via lance injection or rotary degassing unit for maximum hydrogen removal efficiency.<\/p>\n

Primary objective: Dross metal recovery<\/strong>\u00a0\u2192 Specify drossing flux; apply to dross surface and work into dross body to liquefy metal inclusions.<\/p>\n

Primary objective: Inclusion cleanliness<\/strong>\u00a0\u2192 Specify refining flux; combine with ceramic foam filtration downstream for maximum effect.<\/p>\n

Primary objective: Furnace productivity<\/strong>\u00a0\u2192 Specify cleaning flux; apply during planned maintenance periods to dissolve oxide buildup.<\/p>\n

General production improvement<\/strong>\u00a0\u2192 Specify multipurpose flux combining degassing, drossing, and refining functions; best for operations without dedicated flux injection systems.<\/p>\n

\"Aluminum
Aluminum Casting Flux<\/figcaption><\/figure>\n

Degassing Flux: Specifications, Mechanisms, and Application Methods<\/h2>\n

How Degassing Flux Works<\/h3>\n

Degassing flux removes dissolved hydrogen from molten aluminum through a mechanism that differs fundamentally from simple chemical reaction. The flux does not chemically react with dissolved hydrogen \u2014 instead, it creates conditions that allow hydrogen to leave the aluminum melt by diffusion.<\/p>\n

When degassing flux granules or powder are injected into the melt below the surface (via lance or rotary degassing unit), the flux materials vaporize or react to generate very fine gas bubbles. These bubbles \u2014 primarily from the generation of chlorine gas (Cl\u2082) from chloride salt components reacting with aluminum \u2014 rise through the melt. As each rising bubble contacts dissolved hydrogen in the surrounding metal, the hydrogen diffuses from the metal into the bubble interior (driven by the zero partial pressure of hydrogen inside a fresh bubble) and is carried to the surface and removed.<\/p>\n

The efficiency of this process depends on:<\/p>\n

    \n
  • Bubble size:<\/strong> Smaller bubbles have higher surface area per unit volume and collect more hydrogen per unit of gas generated.<\/li>\n
  • Bubble distribution:<\/strong> Uniformly distributed bubbles throughout the melt depth collect hydrogen more efficiently than large bubbles rising in concentrated streams.<\/li>\n
  • Bubble residence time:<\/strong> Slower-rising bubbles (smaller size) spend more time in contact with the metal, collecting more hydrogen.<\/li>\n
  • Melt temperature:<\/strong> Higher temperature increases hydrogen diffusion coefficient, improving removal rate.<\/li>\n<\/ul>\n

    This is why rotary degassing units (which produce very fine, uniformly distributed bubbles through a spinning rotor) dramatically outperform simple lance injection (which produces larger, less uniformly distributed bubbles). Degassing flux amplifies both methods but works much more effectively in rotary degassing systems.<\/p>\n

    AdTech Degassing Flux Chemical Specifications<\/h3>\n
    \n\n\n\n\n\n\n\n\n\n\n\n\n\n
    Parameter<\/th>\nStandard Grade<\/th>\nPremium Grade<\/th>\nTest Method<\/th>\n<\/tr>\n<\/thead>\n
    Primary salt system<\/td>\nKCl + NaCl + Na\u2083AlF\u2086<\/td>\nKCl + NaCl + K\u2082TiF\u2086 + Na\u2083AlF\u2086<\/td>\nXRF \/ wet chemistry<\/td>\n<\/tr>\n
    Chloride content (total)<\/td>\n55\u201370%<\/td>\n50\u201365%<\/td>\nTitration<\/td>\n<\/tr>\n
    Fluoride content<\/td>\n10\u201318%<\/td>\n12\u201320%<\/td>\nIon selective electrode<\/td>\n<\/tr>\n
    Alkali metal content (Na+K)<\/td>\n30\u201345%<\/td>\n28\u201342%<\/td>\nFlame photometry<\/td>\n<\/tr>\n
    Moisture content<\/td>\n\u2264 0.3%<\/td>\n\u2264 0.2%<\/td>\nKarl Fischer \/ LOD<\/td>\n<\/tr>\n
    Particle size (granular)<\/td>\n0.5\u20133.0mm<\/td>\n0.5\u20132.5mm<\/td>\nSieve analysis<\/td>\n<\/tr>\n
    Melting point range<\/td>\n650\u2013720\u00b0C<\/td>\n640\u2013710\u00b0C<\/td>\nDSC analysis<\/td>\n<\/tr>\n
    Bulk density<\/td>\n0.85\u20131.20 g\/cm\u00b3<\/td>\n0.90\u20131.25 g\/cm\u00b3<\/td>\nCylinder method<\/td>\n<\/tr>\n
    pH (10% solution)<\/td>\n7.5\u20139.5<\/td>\n7.5\u20139.5<\/td>\npH meter<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    Degassing Flux Performance Targets<\/h3>\n
    \n\n\n\n\n\n\n\n\n\n\n
    Performance Parameter<\/th>\nBaseline (No Treatment)<\/th>\nAfter Degassing Flux (Lance)<\/th>\nAfter Degassing Flux (Rotary)<\/th>\n<\/tr>\n<\/thead>\n
    Dissolved H\u2082 (ml\/100g Al)<\/td>\n0.30\u20130.60<\/td>\n0.15\u20130.25<\/td>\n0.08\u20130.15<\/td>\n<\/tr>\n
    Density Index (%)<\/td>\n8\u201325%<\/td>\n3\u20138%<\/td>\n1\u20134%<\/td>\n<\/tr>\n
    K-mold Bifilm Index<\/td>\nHigh<\/td>\nModerate<\/td>\nLow-Moderate<\/td>\n<\/tr>\n
    Treatment time (per ton)<\/td>\nN\/A<\/td>\n8\u201315 minutes<\/td>\n12\u201320 minutes<\/td>\n<\/tr>\n
    Flux consumption (kg\/ton Al)<\/td>\nN\/A<\/td>\n1.5\u20133.0 kg<\/td>\n0.8\u20132.0 kg<\/td>\n<\/tr>\n
    Gas consumption (N\u2082 or Ar, m\u00b3\/ton)<\/td>\nN\/A<\/td>\n0.5\u20131.5<\/td>\n2.0\u20135.0<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

    Degassing Flux Application Methods<\/h3>\n

    Method 1: Manual lance injection<\/strong>
    \nA steel lance pipe (diameter 25\u201340mm) attached to a nitrogen or argon gas supply is plunged into the melt. Degassing flux granules or powder are introduced through the lance via a flux injector unit or a simple pressurized hopper. Gas carries the flux into the melt body where it disperses, vaporizes, and generates treatment bubbles.<\/p>\n

    This method is appropriate for small-to-medium operations (melts below 3\u20135 tons) and for operations without rotary degassing equipment. It is lower in capital cost but less efficient in hydrogen removal per kg of flux used.<\/p>\n

    Method 2: Rotary degassing unit with flux injection<\/strong>
    \nA graphite rotor spinning at 200\u2013600 RPM breaks the combined nitrogen\/argon carrier gas and entrained flux powder into very fine bubbles (typical diameter 2\u20138mm versus 15\u201340mm for lance injection). These fine bubbles distribute uniformly through the melt volume, providing dramatically superior hydrogen removal efficiency.<\/p>\n

    AdTech manufactures rotary degassing units (graphite rotor and shaft systems) that integrate directly with our flux product line for optimized system performance. We recommend this method for any operation above 2 tons melt capacity where casting quality is critical.<\/p>\n

    Method 3: Flux tablet\/briquette submergence<\/strong>
    \nPre-formed flux tablets or briquettes are plunged below the melt surface using a steel bell plunger. The tablet dissolves and generates treatment gases. This method is simpler than injection equipment and suitable for smaller operations, though efficiency is lower than rotary degassing.<\/p>\n

    Method 4: Powder spreading with stirring<\/strong>
    \nFor operations with no injection equipment, degassing flux powder can be spread across the melt surface and worked in with a steel ladle or skimmer. This is the least efficient method but provides meaningful improvement over no treatment.<\/p>\n

    Drossing Flux: Specifications, Mechanisms, and Metal Recovery<\/h2>\n

    The Dross Problem in Aluminum Processing<\/h3>\n

    Dross is the surface layer that forms on molten aluminum through oxidation, nitridation, and entrapment of non-metallic materials. In secondary aluminum operations (recycling foundries and smelters), dross generation can represent 2\u20138% of the total melt weight \u2014 with metallic aluminum often comprising 40\u201370% of the dross mass. This trapped metal represents direct revenue loss and is the primary target of drossing flux treatment.<\/p>\n

    The composition of typical aluminum dross:<\/p>\n

      \n
    • Metallic aluminum (trapped): 40\u201370%.<\/li>\n
    • Aluminum oxide (Al\u2082O\u2083): 15\u201335%.<\/li>\n
    • Aluminum nitride (AlN): 5\u201315%.<\/li>\n
    • Magnesium oxide (MgO): 1\u20135% (in Mg-bearing alloys)<\/li>\n
    • Spinels (MgAl\u2082O\u2084): 2\u20138%.<\/li>\n
    • Other salts, carbides, other oxides: 2\u20135%.<\/li>\n<\/ul>\n

      How Drossing Flux Works<\/h3>\n

      Drossing flux acts on the dross layer through two primary mechanisms:<\/p>\n

      Mechanism 1: Reduction of dross melting point and viscosity<\/strong>
      \nThe chloride-fluoride salt components of drossing flux dissolve into the oxide matrix of the dross, reducing its melting point and viscosity. This allows the metallic aluminum droplets trapped within the dross structure to coalesce and drain back into the melt, increasing metal recovery.<\/p>\n

      Mechanism 2: Surface tension modification<\/strong>
      \nDrossing flux reduces the surface tension of the molten aluminum relative to the oxide films, causing oxide films to release their trapped metal content more readily. This is particularly important for the fine, dispersed metal droplets that represent the majority of dross metal content.<\/p>\n

      The practical result: dross treated with appropriate drossing flux becomes fluffy, dry, and non-sticky (sometimes described as “short” dross), making it easy to skim cleanly from the melt surface while leaving maximum metal behind. Untreated dross remains wet, sticky, and difficult to skim \u2014 dragging metal with it and leaving adhesive residue on furnace walls.<\/p>\n

      \"HOW
      HOW ALUMINUM DROSSING FLUX WORKS: REDUCING METAL LOSS & IMPROVING MELT QUALITY<\/figcaption><\/figure>\n

      AdTech Drossing Flux Specifications<\/h3>\n
      \n\n\n\n\n\n\n\n\n\n\n\n\n
      Parameter<\/th>\nStandard Drossing Flux<\/th>\nHeavy-Duty Drossing Flux<\/th>\nLow-Salt Drossing Flux<\/th>\n<\/tr>\n<\/thead>\n
      Primary composition<\/td>\nKCl-NaCl-Na\u2083AlF\u2086<\/td>\nKCl-NaCl-Na\u2083AlF\u2086-KF<\/td>\nOrganic salt + fluoride<\/td>\n<\/tr>\n
      Chloride content<\/td>\n60\u201375%<\/td>\n55\u201370%<\/td>\n20\u201340%<\/td>\n<\/tr>\n
      Fluoride content<\/td>\n8\u201315%<\/td>\n12\u201320%<\/td>\n5\u201315%<\/td>\n<\/tr>\n
      Application temperature<\/td>\n700\u2013760\u00b0C<\/td>\n700\u2013780\u00b0C<\/td>\n680\u2013750\u00b0C<\/td>\n<\/tr>\n
      Particle form<\/td>\nPowder (0.1\u20130.5mm)<\/td>\nGranular (0.5\u20132.0mm)<\/td>\nPowder<\/td>\n<\/tr>\n
      Moisture content<\/td>\n\u2264 0.3%<\/td>\n\u2264 0.25%<\/td>\n\u2264 0.4%<\/td>\n<\/tr>\n
      Dosing rate<\/td>\n5\u201315 kg\/ton dross<\/td>\n8\u201318 kg\/ton dross<\/td>\n4\u201312 kg\/ton dross<\/td>\n<\/tr>\n
      Metal recovery improvement<\/td>\n15\u201335% vs. no flux<\/td>\n20\u201340% vs. no flux<\/td>\n10\u201325% vs. no flux<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

      Dross Metal Recovery Performance Data<\/h3>\n
      \n\n\n\n\n\n\n\n\n\n
      Treatment Method<\/th>\nDross Metal Content (after skimming)<\/th>\nMetal Recovery vs. Baseline<\/th>\n<\/tr>\n<\/thead>\n
      No treatment (baseline)<\/td>\n55\u201370% metal in dross<\/td>\nBaseline<\/td>\n<\/tr>\n
      Manual flux + stirring<\/td>\n35\u201350% metal in dross<\/td>\n+15\u201325% metal recovered<\/td>\n<\/tr>\n
      Mechanical dross press (no flux)<\/td>\n30\u201345% metal in dross<\/td>\n+20\u201330% metal recovered<\/td>\n<\/tr>\n
      Drossing flux + mechanical press<\/td>\n15\u201325% metal in dross<\/td>\n+35\u201350% metal recovered<\/td>\n<\/tr>\n
      AdTech heavy-duty drossing flux<\/td>\n18\u201328% metal in dross<\/td>\n+30\u201345% metal recovered<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

      Dross Application Procedure<\/h3>\n

      The correct drossing flux application sequence maximizes metal recovery:<\/p>\n

        \n
      1. Allow dross to accumulate on the melt surface naturally during the melting cycle.<\/li>\n
      2. Reduce agitation and allow the melt to calm for 2\u20133 minutes before flux application.<\/li>\n
      3. Apply drossing flux powder uniformly across the entire dross surface at the recommended dosing rate.<\/li>\n
      4. Work the flux into the dross using a perforated steel skimmer or mechanical dross stirrer \u2014 the flux must contact the interior of the dross mass, not just the surface.<\/li>\n
      5. Allow 3\u20135 minutes for the flux to act (metal droplets coalesce and drain).<\/li>\n
      6. Skim the treated dross cleanly in one direction, not repeatedly scraping back and forth (which reincorporates metal).<\/li>\n
      7. Check that the melt surface is clean and bright after skimming \u2014 residual dark areas indicate incomplete dross removal.<\/li>\n<\/ol>\n
        \"AdTech
        AdTech aluminum drossing flux<\/figcaption><\/figure>\n

        Covering and Protective Flux: Preventing Oxidation During Melting and Holding<\/h2>\n

        The Need for Melt Surface Protection<\/h3>\n

        Between active treatment operations (degassing, drossing), molten aluminum left exposed to the furnace atmosphere continues to oxidize at the surface. This oxidation generates new dross, absorbs atmospheric hydrogen, and degrades the metal quality that flux treatment has achieved.<\/p>\n

        Covering flux solves this problem by floating as a molten salt layer on the aluminum melt surface, physically separating the metal from the atmosphere. The flux layer must:<\/p>\n

          \n
        • Melt and spread at aluminum holding temperatures (680\u2013750\u00b0C).<\/li>\n
        • Have lower density than aluminum (2.7 g\/cm\u00b3) to float stably.<\/li>\n
        • Create a continuous, non-permeable barrier to atmospheric gases.<\/li>\n
        • Not react chemically with the aluminum or introduce contamination.<\/li>\n
        • Remain fluid enough to be skimmed off before casting.<\/li>\n<\/ul>\n

          AdTech Covering Flux Specifications<\/h3>\n
          \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
          Parameter<\/th>\nStandard Covering Flux<\/th>\nHigh-Temperature Covering Flux<\/th>\n<\/tr>\n<\/thead>\n
          Composition<\/td>\nKCl-NaCl base<\/td>\nKCl-NaCl-K\u2082SO\u2084 base<\/td>\n<\/tr>\n
          Chloride content<\/td>\n65\u201380%<\/td>\n60\u201375%<\/td>\n<\/tr>\n
          Fluoride content<\/td>\n3\u20138%<\/td>\n5\u201312%<\/td>\n<\/tr>\n
          Application temperature<\/td>\n680\u2013740\u00b0C<\/td>\n700\u2013780\u00b0C<\/td>\n<\/tr>\n
          Melting point of flux<\/td>\n620\u2013680\u00b0C<\/td>\n640\u2013700\u00b0C<\/td>\n<\/tr>\n
          Flux density<\/td>\n1.6\u20131.9 g\/cm\u00b3<\/td>\n1.7\u20132.0 g\/cm\u00b3<\/td>\n<\/tr>\n
          Layer thickness (effective)<\/td>\n15\u201330mm<\/td>\n20\u201340mm<\/td>\n<\/tr>\n
          Application rate<\/td>\n5\u201310 kg\/m\u00b2 melt surface<\/td>\n6\u201312 kg\/m\u00b2 melt surface<\/td>\n<\/tr>\n
          H\u2082 absorption prevention<\/td>\n60\u201380% reduction<\/td>\n70\u201385% reduction<\/td>\n<\/tr>\n
          Particle size<\/td>\n2\u20138mm granular<\/td>\n2\u20138mm granular<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

          Covering Flux in Long-Duration Holding Operations<\/h3>\n

          For aluminum holding furnaces that maintain metal at temperature for extended periods (between casting cycles, overnight holding, or shift-change holding periods), covering flux provides a quantifiable benefit. Without covering flux, metal in a gas-fired holding furnace at 720\u00b0C absorbs approximately 0.03\u20130.06 ml H\u2082 per 100g Al per hour of holding. With a properly maintained covering flux layer, this absorption rate drops to 0.005\u20130.015 ml H\u2082 per 100g Al per hour \u2014 a 4\u20136\u00d7 reduction in hydrogen pickup rate during holding.<\/p>\n

          This means that a 4-hour overnight hold that would raise hydrogen content from 0.10 to 0.30 ml\/100g (requiring re-degassing before the next shift’s casting) instead raises it only to 0.12\u20130.15 ml\/100g \u2014 often eliminating the need for re-degassing and saving both treatment time and flux consumption.<\/p>\n

          Furnace Wall Cleaning Flux: Removing Sintered Oxide Buildup<\/h2>\n

          The Furnace Productivity Impact of Oxide Buildup<\/h3>\n

          Over weeks and months of operation, aluminum melting furnaces accumulate sintered oxide buildups (also called skulls or bath crusts) on furnace walls, hearth surfaces, and ramp areas. These buildups:<\/p>\n

            \n
          • Trap metallic aluminum, reducing melt yield.<\/li>\n
          • Reduce furnace capacity as buildup thickness increases.<\/li>\n
          • Create local hot spots from their insulating effect, accelerating refractory wear.<\/li>\n
          • Generate oxide inclusions when pieces break off and enter the melt.<\/li>\n
          • Increase energy consumption per ton of aluminum melted.<\/li>\n<\/ul>\n

            Mechanical removal of these buildups (chipping, grinding) is labor-intensive, risks damaging refractory linings, and cannot access complex furnace geometries. Furnace wall cleaning flux dissolves these buildups chemically during furnace operation.<\/p>\n

            AdTech Furnace Cleaning Flux Specifications<\/h3>\n
            \n\n\n\n\n\n\n\n\n\n\n\n\n
            Parameter<\/th>\nStandard Cleaning Flux<\/th>\nHeavy-Duty Cleaning Flux<\/th>\n<\/tr>\n<\/thead>\n
            Primary system<\/td>\nKF-NaF-Na\u2083AlF\u2086<\/td>\nNa\u2083AlF\u2086-K\u2082TiF\u2086-KCl<\/td>\n<\/tr>\n
            Fluoride content<\/td>\n25\u201340%<\/td>\n35\u201350%<\/td>\n<\/tr>\n
            Application temperature<\/td>\n720\u2013780\u00b0C<\/td>\n740\u2013800\u00b0C<\/td>\n<\/tr>\n
            Physical form<\/td>\nGranular (1\u20134mm)<\/td>\nGranular (2\u20135mm)<\/td>\n<\/tr>\n
            Application frequency<\/td>\nMonthly or quarterly<\/td>\nQuarterly or semi-annual<\/td>\n<\/tr>\n
            Application method<\/td>\nDirect on oxide buildup<\/td>\nWith raking\/stirring<\/td>\n<\/tr>\n
            Oxide dissolution rate<\/td>\n2\u20135 kg oxide\/kg flux<\/td>\n3\u20137 kg oxide\/kg flux<\/td>\n<\/tr>\n
            Contact time required<\/td>\n15\u201345 minutes<\/td>\n20\u201360 minutes<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

            Cleaning Flux Application Protocol<\/h3>\n
              \n
            1. Allow furnace to reach treatment temperature (720\u2013780\u00b0C) with melt present.<\/li>\n
            2. Reduce or stop metal flow into the furnace.<\/li>\n
            3. Apply cleaning flux directly onto the oxide buildup areas.<\/li>\n
            4. Allow flux to react without disturbance for 15\u201330 minutes.<\/li>\n
            5. Rake softened oxide buildup into the melt body where it dissolves into the flux layer.<\/li>\n
            6. Skim the resulting flux-oxide mixture from the melt surface.<\/li>\n
            7. Resume normal operations after removing cleaning flux residue.<\/li>\n<\/ol>\n

              We recommend scheduling cleaning flux treatment during planned maintenance windows rather than during production, since the process temporarily reduces melt quality and generates substantial dross.<\/p>\n

              Flux Chemistry: Chloride-Fluoride Salt Systems and Their Metallurgical Functions<\/h2>\n

              The Foundation: Why KCl-NaCl-Fluoride Systems Work<\/h3>\n

              The dominant chemistry in commercial aluminum melt treatment fluxes is the potassium chloride-sodium chloride-fluoride system. Understanding why this particular chemistry is chosen explains how to evaluate and compare flux products.<\/p>\n

              Potassium chloride (KCl) and sodium chloride (NaCl):<\/strong>
              \nThe KCl-NaCl binary system forms a eutectic at approximately 51% NaCl \/ 49% KCl (by weight) with a melting point of 657\u00b0C \u2014 conveniently below typical aluminum processing temperatures (680\u2013780\u00b0C). This eutectic composition produces a low-viscosity molten salt that spreads readily over aluminum melt surfaces and penetrates dross structures effectively.<\/p>\n

              The alkali chlorides (KCl, NaCl) are the carrier phase for the more reactive fluoride components and provide the low melting point and good fluidity that makes the flux functionally useful.<\/p>\n

              Fluoride components (Na\u2083AlF\u2086, KF, K\u2082TiF\u2086, Na\u2082SiF\u2086):<\/strong>
              \nFluoride compounds are the chemically active components that provide the flux’s metallurgical effectiveness. Their functions include:<\/p>\n

                \n
              • Cryolite (Na\u2083AlF\u2086):<\/strong>\u00a0Dissolves aluminum oxide (Al\u2082O\u2083) films, enabling oxide inclusions to be incorporated into the flux phase rather than remaining in the metal. Also reduces the melting point of the salt mixture.<\/li>\n
              • Potassium fluoride (KF):<\/strong>\u00a0Aggressive oxide dissolver; improves wetting of flux onto metal surfaces; contributes to alkali metal removal from the melt.<\/li>\n
              • Potassium fluorotitanate (K\u2082TiF\u2086):<\/strong>\u00a0Used in premium degassing flux formulations; releases titanium fluoride complexes that improve the efficiency of hydrogen bubble nucleation on flux particles.<\/li>\n
              • Sodium hexafluorosilicate (Na\u2082SiF\u2086):<\/strong>\u00a0Less common; used in some cleaning flux formulations for aggressive oxide dissolution.<\/li>\n<\/ul>\n

                Salt-Free and Low-Chloride Flux Alternatives<\/h3>\n

                Regulatory pressure in several countries (particularly European Union members with tight chloride emission limits) has driven development of alternative flux chemistries that reduce or eliminate chloride content:<\/p>\n

                Organic salt systems:<\/strong>\u00a0Some flux formulations replace chloride salts partially with organic compounds (glycines, oxalates) that provide degassing action through thermal decomposition without generating HCl gas. These are less efficient than chloride-based systems but acceptable in regulatory environments requiring chloride emission reduction.<\/p>\n

                Nitrogen\/argon-only degassing:<\/strong>\u00a0The most extreme low-emission approach eliminates chemical flux entirely, relying solely on inert gas bubbling through rotary degassing equipment. Efficiency is somewhat lower than combined gas-flux treatment, but regulatory compliance is straightforward.<\/p>\n

                AdTech low-chloride flux range:<\/strong>\u00a0We produce a dedicated low-chloride flux series for customers in emission-regulated markets, formulated to reduce HCl gas generation by 60\u201380% versus standard chloride-based flux while maintaining 80\u201390% of the metallurgical performance of full-chloride formulations.<\/p>\n

                Flux Application Methods: Lance Injection, Rotary Degassing, and Manual Application<\/h2>\n

                Comparative Efficiency of Application Methods<\/h3>\n

                The same flux product delivers dramatically different results depending on the application method. This is one of the most important and least-understood aspects of aluminum flux treatment in practice.<\/p>\n

                \n\n\n\n\n\n\n\n\n\n
                Application Method<\/th>\nH\u2082 Removal Efficiency<\/th>\nFlux Consumption (kg\/ton Al)<\/th>\nCapital Cost<\/th>\nBest For<\/th>\n<\/tr>\n<\/thead>\n
                Surface spread + stirring<\/td>\n20\u201335% H\u2082 reduction<\/td>\n3.0\u20135.0<\/td>\nVery Low<\/td>\nSmall operations, emergency treatment<\/td>\n<\/tr>\n
                Flux tablet plunging<\/td>\n30\u201350% H\u2082 reduction<\/td>\n2.0\u20134.0<\/td>\nLow<\/td>\nSmall to medium foundries<\/td>\n<\/tr>\n
                Lance injection (N\u2082 carrier)<\/td>\n45\u201365% H\u2082 reduction<\/td>\n1.5\u20133.0<\/td>\nLow-Medium<\/td>\nMedium foundries without rotary unit<\/td>\n<\/tr>\n
                Rotary degassing unit<\/td>\n60\u201380% H\u2082 reduction<\/td>\n0.8\u20132.0<\/td>\nMedium-High<\/td>\nAny operation requiring low porosity<\/td>\n<\/tr>\n
                Rotary + flux injection combined<\/td>\n70\u201390% H\u2082 reduction<\/td>\n0.5\u20131.5<\/td>\nHigh<\/td>\nCritical quality applications<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                Rotary Degassing Unit Integration with Flux Treatment<\/h3>\n

                AdTech manufactures graphite rotor and shaft degassing systems that integrate with our flux injection product line. The rotary degassing unit approach to flux application offers several advantages over lance injection:<\/p>\n

                Finer bubble generation:<\/strong>\u00a0The spinning rotor (200\u2013600 RPM) breaks the combined gas-flux stream into bubbles typically 2\u20135mm diameter, versus 15\u201340mm for lance injection. Smaller bubbles have 6\u201310\u00d7 more surface area per unit volume, dramatically improving hydrogen collection efficiency per cubic meter of gas used.<\/p>\n

                Uniform distribution:<\/strong>\u00a0The rotor’s horizontal pumping action distributes bubbles throughout the melt volume rather than allowing them to rise in concentrated columns from a fixed lance position.<\/p>\n

                Reduced flux consumption:<\/strong>\u00a0Because each bubble is smaller and carries hydrogen more efficiently, less total flux is needed per ton of aluminum treated to achieve equivalent hydrogen reduction.<\/p>\n

                Consistent results:<\/strong>\u00a0Operator variability has minimal impact on rotary degassing results \u2014 the rotor speed, gas flow rate, and treatment time fully determine the metallurgical outcome, unlike lance injection where operator technique significantly affects bubble distribution.<\/p>\n

                Treatment Protocol for Rotary Degassing with Flux<\/h3>\n

                The following protocol applies to standard aluminum alloy degassing using AdTech degassing flux with a rotary degassing unit:<\/p>\n

                \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
                Step<\/th>\nAction<\/th>\nParameter<\/th>\n<\/tr>\n<\/thead>\n
                1. Temperature verification<\/td>\nCheck melt temperature<\/td>\nTarget 710\u2013740\u00b0C (720\u00b0C optimal)<\/td>\n<\/tr>\n
                2. Dross removal<\/td>\nSkim existing dross before degassing<\/td>\nRemove all visible dross<\/td>\n<\/tr>\n
                3. Rotor insertion<\/td>\nLower rotor to 100\u2013150mm above hearth<\/td>\nAvoid contact with hearth<\/td>\n<\/tr>\n
                4. Gas purge (no rotation)<\/td>\nPurge gas lines and rotor<\/td>\n30 seconds at low flow<\/td>\n<\/tr>\n
                5. Start rotation<\/td>\nInitiate rotor rotation<\/td>\nRamp to 300\u2013400 RPM<\/td>\n<\/tr>\n
                6. Gas flow<\/td>\nSet carrier gas (N\u2082 or Ar)<\/td>\n4\u20138 L\/min per ton Al<\/td>\n<\/tr>\n
                7. Flux injection<\/td>\nStart flux feed<\/td>\n0.8\u20131.5 kg\/ton Al over treatment duration<\/td>\n<\/tr>\n
                8. Treatment duration<\/td>\nMaintain full treatment<\/td>\n12\u201318 minutes per ton<\/td>\n<\/tr>\n
                9. Final purge<\/td>\nGas without flux (last 2 minutes)<\/td>\nPurge residual flux from rotor<\/td>\n<\/tr>\n
                10. Rotor removal<\/td>\nLift rotor before stopping rotation<\/td>\nPrevent metal splash<\/td>\n<\/tr>\n
                11. Post-treatment dross<\/td>\nRemove treatment byproduct dross<\/td>\nSkim clean before casting<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                Technical Specifications and Performance Data for AdTech Flux Products<\/h2>\n

                AdTech Complete Flux Product Specifications<\/h3>\n
                \n\n\n\n\n\n\n\n\n\n\n\n\n
                Product<\/th>\nType<\/th>\nComposition (main)<\/th>\nForm<\/th>\nDosing Rate<\/th>\nPrimary Application<\/th>\n<\/tr>\n<\/thead>\n
                AdTech DG-1<\/td>\nDegassing flux<\/td>\nKCl 45%, NaCl 25%, Na\u2083AlF\u2086 20%, K\u2082TiF\u2086 10%<\/td>\nGranular 0.5\u20132mm<\/td>\n1.0\u20132.0 kg\/ton<\/td>\nRotary degassing injection<\/td>\n<\/tr>\n
                AdTech DG-2<\/td>\nDegassing flux<\/td>\nKCl 40%, NaCl 30%, Na\u2083AlF\u2086 18%, KF 12%<\/td>\nPowder 0.1\u20130.5mm<\/td>\n1.5\u20133.0 kg\/ton<\/td>\nLance injection<\/td>\n<\/tr>\n
                AdTech DR-1<\/td>\nDrossing flux<\/td>\nKCl 55%, NaCl 20%, Na\u2083AlF\u2086 15%, KF 10%<\/td>\nPowder 0.1\u20130.5mm<\/td>\n5\u201315 kg\/ton dross<\/td>\nSurface dross treatment<\/td>\n<\/tr>\n
                AdTech DR-2<\/td>\nHeavy drossing flux<\/td>\nKCl 50%, NaCl 18%, Na\u2083AlF\u2086 18%, KF 14%<\/td>\nGranular 0.5\u20132mm<\/td>\n8\u201318 kg\/ton dross<\/td>\nSecondary smelter dross<\/td>\n<\/tr>\n
                AdTech CV-1<\/td>\nCovering flux<\/td>\nKCl 65%, NaCl 25%, Na\u2083AlF\u2086 10%<\/td>\nGranular 2\u20138mm<\/td>\n5\u201310 kg\/m\u00b2<\/td>\nHolding furnace protection<\/td>\n<\/tr>\n
                AdTech RF-1<\/td>\nRefining flux<\/td>\nKCl 40%, NaCl 20%, Na\u2083AlF\u2086 25%, KF 15%<\/td>\nPowder 0.1\u20130.5mm<\/td>\n1.5\u20133.0 kg\/ton<\/td>\nInclusion removal + alkali removal<\/td>\n<\/tr>\n
                AdTech CL-1<\/td>\nCleaning flux<\/td>\nNa\u2083AlF\u2086 40%, KF 30%, KCl 30%<\/td>\nGranular 1\u20134mm<\/td>\n10\u201320 kg\/m\u00b2 oxide<\/td>\nFurnace wall cleaning<\/td>\n<\/tr>\n
                AdTech LC-1<\/td>\nLow-chloride flux<\/td>\nOrganic salt 50%, fluoride 35%, KCl 15%<\/td>\nPowder 0.1\u20130.5mm<\/td>\n1.5\u20132.5 kg\/ton<\/td>\nEmission-regulated operations<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                Performance Validation Data<\/h3>\n

                AdTech flux products are tested against the following performance criteria before release to market:<\/p>\n

                \n\n\n\n\n\n\n\n\n\n\n\n\n
                Test Parameter<\/th>\nMethod<\/th>\nAcceptance Criterion<\/th>\n<\/tr>\n<\/thead>\n
                Moisture content<\/td>\nKarl Fischer titration<\/td>\n\u2264 0.30%<\/td>\n<\/tr>\n
                Chemical composition (XRF)<\/td>\nXRF analysis<\/td>\nWithin \u00b12% of specification<\/td>\n<\/tr>\n
                Melting point<\/td>\nDSC \/ hot plate test<\/td>\nWithin 20\u00b0C of target<\/td>\n<\/tr>\n
                Particle size distribution<\/td>\nSieve analysis<\/td>\nWithin specification \u00b110%<\/td>\n<\/tr>\n
                Degassing efficiency (aluminum test)<\/td>\nDensity Index before\/after<\/td>\n\u2265 50% DI reduction (DG grades)<\/td>\n<\/tr>\n
                Metal recovery (drossing test)<\/td>\nControlled dross treatment<\/td>\n\u2265 20% metal recovery improvement (DR grades)<\/td>\n<\/tr>\n
                Hydrogen absorption prevention<\/td>\nTimed exposure test<\/td>\n\u2265 60% H\u2082 absorption reduction (CV grades)<\/td>\n<\/tr>\n
                Chloride emission (HCl gas)<\/td>\nGas measurement during application<\/td>\nWithin environmental compliance limits<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                Interaction Between Flux Treatment and Ceramic Foam Filtration<\/h2>\n

                Why Flux and Filtration Are Complementary, Not Alternatives<\/h3>\n

                A misconception we encounter regularly is the idea that a foundry must choose between flux treatment and ceramic foam filtration \u2014 that installing a filtration system means flux treatment becomes unnecessary. This reflects a misunderstanding of what each process accomplishes.<\/p>\n

                Flux treatment (degassing and drossing) removes:<\/strong><\/p>\n

                  \n
                • Dissolved hydrogen gas (filtration cannot do this)<\/li>\n
                • Large oxide films and dross from the melt surface and body (through flotation and coagulation)<\/li>\n
                • Alkali metals (Na, Ca, K) that increase hydrogen absorption tendency.<\/li>\n
                • Coarsely distributed inclusions through skimming.<\/li>\n<\/ul>\n

                  Ceramic foam filtration removes:<\/strong><\/p>\n

                    \n
                  • Fine oxide bifilms and inclusion particles that remain after flux treatment.<\/li>\n
                  • Small refractory fragments.<\/li>\n
                  • Fine intermetallic particles.<\/li>\n
                  • The inclusion population that flux treatment leaves behind but that still causes casting defects.<\/li>\n<\/ul>\n

                    The two technologies address different inclusion size ranges and different metallurgical problems. Flux treatment handles the gross hydrogen and large inclusion problem; filtration handles the fine inclusion population that remains after treatment. Used together, they produce metal quality that neither achieves independently.<\/p>\n

                    The Correct Process Sequence<\/h3>\n

                    The correct sequence for aluminum melt treatment before casting:<\/p>\n

                    1. Charge and melt<\/strong> \u2192 Load furnace and melt the charge.<\/p>\n

                    2. Alloy and temperature adjustment<\/strong> \u2192 Add alloying elements, adjust temperature.<\/p>\n

                    3. Drossing flux treatment<\/strong> \u2192 Apply drossing flux, work, and skim dross.<\/p>\n

                    4. Degassing flux treatment<\/strong> \u2192 Apply degassing flux via rotary unit or lance; complete hydrogen removal.<\/p>\n

                    5. Post-treatment dross removal<\/strong> \u2192 Skim byproduct dross from degassing treatment.<\/p>\n

                    6. Grain refiner addition<\/strong> \u2192 Add AlTi5B1 or AlTiB2 grain refiner (5\u201310 minutes before casting).<\/p>\n

                    7. Transfer to casting station<\/strong> \u2192 Minimize turbulence and reoxidation during transfer.<\/p>\n

                    8. Ceramic foam filtration<\/strong> \u2192 Filter during mould filling through Al\u2082O\u2083 foam filter in the gating system.<\/p>\n

                    9. Casting<\/strong> \u2192 Fill mould through filtered metal stream.<\/p>\n

                    This sequence is not arbitrary \u2014 placing filtration after flux treatment ensures the filter sees relatively clean metal (flux has removed large inclusions), maximizing filter service life and extending the period before premature blockage occurs.<\/p>\n

                    Safety, Environmental Compliance, and Handling Requirements<\/h2>\n

                    Health and Safety Hazards in Flux Handling<\/h3>\n

                    Aluminum melt treatment fluxes are industrial chemicals that require appropriate handling controls:<\/p>\n

                    Moisture sensitivity:<\/strong>\u00a0All chloride-fluoride flux products absorb atmospheric moisture aggressively. Reacting flux with moist atmosphere generates hydrogen chloride (HCl) gas \u2014 a severe respiratory irritant. Store flux in sealed containers in dry conditions. Never introduce wet flux into a molten aluminum bath \u2014 the violent steam generation can spray molten metal.<\/p>\n

                    HCl gas generation during application:<\/strong>\u00a0When chloride-containing flux contacts molten aluminum, hydrogen chloride (HCl) and chlorine (Cl\u2082) gases are generated as byproducts of the degassing reaction. Both gases are respiratory irritants and corrosive. Flux treatment areas must have adequate local exhaust ventilation to maintain HCl concentrations below OSHA PEL of 5 ppm (ceiling limit).<\/p>\n

                    Hydrogen fluoride (HF) generation:<\/strong>\u00a0Fluoride components can generate HF gas under some conditions, particularly at high temperatures or with wet flux. HF is a severe systemic toxin \u2014 OSHA PEL of 3 ppm TWA. Respiratory protection and ventilation are essential.<\/p>\n

                    Molten salt burns:<\/strong>\u00a0Flux materials melt at 650\u2013720\u00b0C and behave as energetic molten liquids during application. Contact with skin causes severe thermal and chemical burns. Full PPE (face shield, heat-resistant gloves, aluminized suit for close work) is required.<\/p>\n

                    Required PPE for Flux Application<\/h3>\n
                    \n\n\n\n\n\n\n\n\n\n
                    Task<\/th>\nRequired PPE<\/th>\n<\/tr>\n<\/thead>\n
                    Flux bag handling \/ transfer<\/td>\nSafety glasses, N95 respirator, nitrile gloves<\/td>\n<\/tr>\n
                    Lance injection operation<\/td>\nFace shield, N95\u2013P100 respirator, heat-resistant gloves, flame-resistant clothing<\/td>\n<\/tr>\n
                    Rotary degassing operation<\/td>\nFace shield, P100 respirator, heat-resistant gloves, FR clothing<\/td>\n<\/tr>\n
                    Dross skimming after treatment<\/td>\nFace shield, P100 respirator, heat-resistant gloves, FR clothing<\/td>\n<\/tr>\n
                    Flux storage area inspection<\/td>\nSafety glasses, dust mask<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                    Environmental Compliance<\/h3>\n

                    Chloride emissions:<\/strong>\u00a0HCl gas from flux treatment is regulated under Clean Air Act (USA), EU Industrial Emissions Directive, and equivalent national regulations. Permissible emission levels vary by jurisdiction and facility size. Foundries with enclosed degassing stations typically use wet scrubbers or dry sodium bicarbonate scrubbing systems to capture HCl before atmospheric discharge.<\/p>\n

                    Fluoride emissions:<\/strong>\u00a0HF and particulate fluoride from flux treatment are regulated similarly to chloride emissions. Foundries in regulated jurisdictions should conduct emissions testing after any significant change in flux consumption rate or flux chemistry.<\/p>\n

                    Spent flux \/ salt slag disposal:<\/strong>\u00a0The salt slag produced after flux treatment (a mixture of salt flux, aluminum oxide, and entrapped metal) must be disposed of according to applicable hazardous waste regulations. In many jurisdictions, aluminum salt slag is classified as hazardous waste (due to water-reactive aluminum nitride content that generates ammonia and potentially flammable gas on contact with water). AdTech provides waste stream characterization data for our flux products to support customer environmental compliance.<\/p>\n

                    REACH \/ SDS compliance:<\/strong>\u00a0All AdTech flux products are registered under applicable chemical control regulations and supplied with current Safety Data Sheets in required languages.<\/p>\n

                    Selecting the Right Flux for Your Aluminum Alloy and Process<\/h2>\n

                    Alloy-Specific Flux Selection Considerations<\/h3>\n

                    Different aluminum alloy families present different flux treatment challenges:<\/p>\n

                    \n\n\n\n\n\n\n\n\n\n\n\n
                    Alloy Family<\/th>\nMain Challenge<\/th>\nRecommended Flux Type<\/th>\nSpecial Consideration<\/th>\n<\/tr>\n<\/thead>\n
                    Al-Si (A356, A380, ADC12)<\/td>\nHydrogen porosity; oxide bifilms<\/td>\nDG-1 or DG-2 degassing + DR-1 drossing<\/td>\nStandard treatment; most common<\/td>\n<\/tr>\n
                    Al-Si-Mg (A357)<\/td>\nMg oxidation; MgAl\u2082O\u2084 spinel<\/td>\nDG-1 + RF-1 refining<\/td>\nMg-bearing alloys generate more dross<\/td>\n<\/tr>\n
                    Al-Cu (2xx.x)<\/td>\nHigh H\u2082 absorption at high temp<\/td>\nDG-1 rotary + CV-1 covering<\/td>\nHigher treatment temperature required<\/td>\n<\/tr>\n
                    Al-Mg (5xx.x)<\/td>\nAggressive surface oxidation<\/td>\nDR-2 heavy drossing + CV-1<\/td>\nMg content dramatically increases dross rate<\/td>\n<\/tr>\n
                    Al-Zn-Mg (7xx.x)<\/td>\nComplex oxide; Zn volatility<\/td>\nDG-2 + RF-1<\/td>\nZinc fume management required<\/td>\n<\/tr>\n
                    Secondary \/ recycled alloys<\/td>\nVery high inclusion load<\/td>\nDR-2 + DG-1 + RF-1 combined<\/td>\nMore aggressive treatment needed<\/td>\n<\/tr>\n
                    High-purity Al (1xxx)<\/td>\nHydrogen absorption; minimal other issues<\/td>\nDG-1 (low dose)<\/td>\nVery clean; minimal drossing flux needed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                    Process-Specific Flux Dosing Guide<\/h3>\n
                    \n\n\n\n\n\n\n\n\n\n\n\n
                    Process Type<\/th>\nFurnace Size<\/th>\nRecommended Flux Products<\/th>\nTotal Flux Dose (kg\/ton Al)<\/th>\n<\/tr>\n<\/thead>\n
                    Gravity die casting (small)<\/td>\n0.5\u20132 tons<\/td>\nDG-2 lance + DR-1<\/td>\n2.5\u20134.5 kg\/ton<\/td>\n<\/tr>\n
                    Gravity die casting (medium)<\/td>\n2\u201310 tons<\/td>\nDG-1 rotary + DR-1<\/td>\n2.0\u20133.5 kg\/ton<\/td>\n<\/tr>\n
                    High pressure die casting<\/td>\n5\u201330 tons<\/td>\nDG-1 rotary + DR-2<\/td>\n1.5\u20133.0 kg\/ton<\/td>\n<\/tr>\n
                    Low pressure casting<\/td>\n2\u201315 tons<\/td>\nDG-1 rotary + CV-1 + DR-1<\/td>\n2.5\u20134.0 kg\/ton<\/td>\n<\/tr>\n
                    Investment casting<\/td>\n0.1\u20132 tons<\/td>\nDG-2 + RF-1 tablet<\/td>\n3.0\u20135.0 kg\/ton<\/td>\n<\/tr>\n
                    Secondary smelting<\/td>\n20\u2013100 tons<\/td>\nDG-1 + DR-2 heavy + CL-1 periodic<\/td>\n3.0\u20136.0 kg\/ton<\/td>\n<\/tr>\n
                    Continuous casting<\/td>\n50\u2013200 tons<\/td>\nDG-1 inline + CV-1 + CFL (periodic)<\/td>\n1.0\u20132.5 kg\/ton<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

                    Frequently Asked Questions (FAQs)<\/h2>\n

                    Q1: What is the difference between degassing flux and drossing flux for aluminum, and do I need both?<\/strong><\/p>\n

                    Degassing flux and drossing flux perform fundamentally different functions. Degassing flux removes dissolved hydrogen gas from the melt body by generating fine bubbles that carry hydrogen to the surface \u2014 this reduces casting porosity. Drossing flux acts on the dross layer at the melt surface, reducing its viscosity so that trapped metallic aluminum droplets coalesce and drain back into the melt, improving metal recovery and producing dry, easily-skimmed dross. Most production aluminum foundries benefit from both: degassing flux addresses the internal porosity problem, while drossing flux reduces metal loss and surface inclusion generation. Some multipurpose flux formulations provide both functions simultaneously, though at slightly lower efficiency than dedicated single-purpose products.<\/p>\n

                    Q2: How much hydrogen can degassing flux realistically remove from molten aluminum?<\/strong><\/p>\n

                    The achievable hydrogen reduction depends critically on the application method. Using degassing flux with a rotary degassing unit at the correct dosing rate (0.8\u20132.0 kg\/ton) and treatment time (12\u201320 minutes per ton), dissolved hydrogen content in secondary aluminum melts can be reduced from 0.30\u20130.60 ml H\u2082 per 100g Al down to 0.08\u20130.15 ml\/100g \u2014 a 50\u201375% reduction. Lance injection without a rotary unit achieves a more modest 40\u201360% reduction. Simple surface application achieves only 20\u201335% reduction. The rotary degassing unit combined with flux injection is the most effective approach for castings requiring low porosity, particularly automotive safety components and pressure-tight castings.<\/p>\n

                    Q3: Why does my degassing flux generate so much smoke and fumes during application?<\/strong><\/p>\n

                    Smoke and fume generation during flux application is normal and expected \u2014 it is a byproduct of the flux chemistry performing its function. The visible fumes are primarily hydrogen chloride (HCl) gas and fine salt particles generated when chloride salts react with moisture and aluminum oxide in the melt. Excessive smoke beyond the normal treatment amount may indicate: wet or moisture-contaminated flux (check storage conditions and container integrity), flux application rate too high for the available ventilation (reduce dosing rate or improve ventilation), or abnormally high moisture content in the melt or furnace atmosphere. Always ensure local exhaust ventilation is operating before starting flux treatment, and wear appropriate respiratory protection regardless of visible smoke level, since HCl is odorless at sub-irritating concentrations.<\/p>\n

                    Q4: Can I use the same flux for both aluminum alloys with different magnesium content?<\/strong><\/p>\n

                    The base flux chemistry (KCl-NaCl-fluoride system) is compatible with all aluminum alloys, but magnesium-bearing alloys (A356, A357, Mg > 0.2%) require modified treatment approaches. Magnesium oxidizes more aggressively than aluminum, generating significantly more dross per ton of metal. For high-Mg alloys: increase drossing flux dosing rate by 25\u201340%, use a heavy-duty drossing flux (AdTech DR-2) rather than standard drossing flux, and increase covering flux application rate to protect the Mg-containing melt surface between treatment cycles. Magnesium also slightly reduces the efficiency of degassing flux by reacting preferentially with some fluoride components \u2014 this effect is minor at Mg < 0.5% but meaningful at higher Mg levels.<\/p>\n

                    Q5: What is Density Index and how does it measure flux treatment effectiveness?<\/strong><\/p>\n

                    The Density Index (DI) test is the most widely used field measurement of dissolved hydrogen content in molten aluminum. Two small metal samples are solidified simultaneously \u2014 one at atmospheric pressure, one under vacuum (typically 80\u2013100 mbar). Both samples are weighed. The Density Index is calculated as: DI (%) = (atmospheric density \u2014 vacuum density) \/ atmospheric density \u00d7 100. A DI of 0% indicates no porosity difference between samples (essentially hydrogen-free metal). A DI above 5% indicates significant dissolved hydrogen. Most automotive casting specifications require DI below 2\u20134%. Aerospace applications typically require DI below 1\u20132%. Take DI measurements before and after flux treatment to directly quantify the treatment effect: a well-executed rotary degassing treatment with AdTech degassing flux should reduce DI from 8\u201320% (untreated secondary aluminum) to 1\u20134%.<\/p>\n

                    Q6: How long after degassing treatment does molten aluminum remain clean before hydrogen pick-up becomes a problem again?<\/strong><\/p>\n

                    Degassed aluminum reabsorbs hydrogen from the furnace atmosphere at a rate that depends primarily on furnace atmosphere moisture content and melt surface condition. In a gas-fired furnace with exposed melt surface, hydrogen reabsorption raises the dissolved content by approximately 0.03\u20130.08 ml H\u2082 per 100g Al per hour. In an induction furnace with lower moisture exposure, reabsorption is slower (0.01\u20130.04 ml\/100g per hour). With covering flux maintaining a salt layer over the melt surface, reabsorption slows to approximately 0.005\u20130.020 ml\/100g per hour. Practical implication: for standard castings, degassed metal should be cast within 30\u201360 minutes of treatment. For critical applications (aerospace, pressure-tight parts), cast within 20\u201330 minutes. If holding time exceeds these limits, re-treat with a reduced-dose degassing flux before casting.<\/p>\n

                    Q7: What is the correct temperature for aluminum flux treatment, and does temperature significantly affect performance?<\/strong><\/p>\n

                    The optimal temperature window for most aluminum melt flux treatment is 710\u2013740\u00b0C, with 720\u00b0C being ideal for standard alloys. This temperature window balances: metal fluidity (higher temperature improves flux distribution and bubble release), flux activity (most flux systems have optimal reaction kinetics at 700\u2013740\u00b0C), and hydrogen diffusion rate (higher temperature increases hydrogen diffusion coefficient, improving removal rate). Treatment below 680\u00b0C reduces flux effectiveness because the flux melting point approaches the metal temperature, reducing flux fluidity and penetration. Treatment above 780\u00b0C accelerates melt oxidation and increases hydrogen absorption rate from furnace gases. For Al-Cu alloys that process at higher temperatures, consult AdTech’s technical team for flux selection optimized for the 740\u2013780\u00b0C range.<\/p>\n

                    Q8: How should I store aluminum melt treatment flux to maintain its effectiveness?<\/strong><\/p>\n

                    Correct storage is critical for chloride-fluoride flux performance. All AdTech flux products must be stored: in sealed, moisture-proof containers (original sealed bags or drums); in dry conditions with relative humidity below 60%; at ambient temperature (5\u201335\u00b0C), protected from direct sunlight and heat sources; away from water, acids, and incompatible chemicals. Flux exposed to atmospheric moisture absorbs water, which causes clumping, reduces flowability (affecting injection performance), and increases HCl generation during application. Check all containers for seal integrity before use. Do not use flux from damaged or previously opened containers without drying in a controlled oven (120\u00b0C for 4\u20138 hours) if moisture exposure is suspected. Shelf life for properly stored AdTech flux products is 24 months from manufacture date.<\/p>\n

                    Q9: Can flux treatment alone eliminate porosity in aluminum castings, or is filtration also needed?<\/strong><\/p>\n

                    Flux treatment and ceramic foam filtration address different aspects of aluminum casting quality, and neither alone achieves optimal results. Degassing flux removes dissolved hydrogen \u2014 the primary cause of shrinkage microporosity and gas porosity in aluminum castings. However, flux treatment leaves behind a residual population of fine oxide bifilms and inclusion particles that are too small to be captured by skimming or flotation. These fine inclusions \u2014 typically smaller than 0.5mm \u2014 are responsible for bifilm-related porosity (where the unbonded bifilm interface acts as a void in the solidified metal), mechanical property scatter, and machined surface defects. Ceramic foam filtration (30\u201340 PPI Al\u2082O\u2083 filter in the gating system) captures these residual fine inclusions that flux treatment misses. The combination of proper flux treatment followed by ceramic foam filtration consistently achieves lower porosity and better mechanical property consistency than either process alone.<\/p>\n

                    Q10: What is the recommended flux treatment procedure for a secondary aluminum die casting operation producing A380 alloy?<\/strong><\/p>\n

                    For secondary aluminum A380 die casting, the recommended treatment sequence using AdTech products is: (1) At the end of the melt cycle, when metal reaches 720\u2013730\u00b0C, remove large floating dross by skimming; (2) Apply AdTech DR-1 drossing flux at 5\u201310 kg per ton of accumulated dross, work into the dross surface with a perforated skimmer, allow 3\u20135 minutes contact time, then skim treated dross cleanly; (3) Introduce the rotary degassing unit (or lance if rotary unit unavailable) and apply AdTech DG-1 degassing flux at 1.0\u20131.5 kg\/ton aluminum in the furnace, using nitrogen carrier gas at 5\u20137 L\/min per ton, treatment duration 12\u201315 minutes; (4) After degassing, apply AdTech CV-1 covering flux at 5 kg\/m\u00b2 melt surface to protect the treated metal until casting; (5) Before tapping, remove covering flux residue and check DI (target below 3% for standard die casting); (6) Filter the metal stream through AdTech Al\u2082O\u2083 20\u201325 PPI ceramic foam filter during shot into the die casting machine shot sleeve.
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