ALCLAR HP-21 is a high-molecular-weight anionic polyacrylamide (APAM) specifically developed for demanding solid–liquid separation processes in mineral processing, alumina refining, and industrial water treatment. Owing to its strong anionic charge and long polymer chains, ALCLAR HP-21 is highly effective at aggregating fine inorganic particles into large, fast-settling flocs. This results in improved settling rates, enhanced clarification, higher underflow densities, and increased water recovery, making it a key reagent in large-scale continuous operations.

One of the most important application areas of ALCLAR HP-21 is the alumina refining industry, particularly in the Bayer process. During bauxite digestion, large quantities of insoluble residues known as red mud are generated. These fine particles must be efficiently separated from the sodium aluminate liquor to ensure stable downstream processing. ALCLAR HP-21 is widely used in red mud settlers, thickeners, and washer circuits, where it promotes rapid flocculation of fine red mud solids. The polymer adsorbs onto negatively charged mineral surfaces and forms inter-particle bridges, creating strong, shear-resistant flocs that settle quickly even under high alkaline conditions.

In primary red mud thickeners, ALCLAR HP-21 significantly increases settling velocity and improves overflow clarity. Clear overflow liquor is essential to prevent scaling, fouling, and impurities in precipitation and evaporation units. At the same time, the thickener underflow becomes more concentrated, reducing mud volume and improving handling efficiency. This leads to lower pumping energy, reduced equipment wear, and improved overall refinery productivity.

ALCLAR HP-21 is also extensively applied in red mud washing operations, especially in counter-current decantation (CCD) systems. Efficient flocculation allows rapid solid–liquid separation in each washer stage, ensuring that entrained caustic soda and dissolved alumina are effectively recovered from the mud. By improving washing efficiency, ALCLAR HP-21 helps minimize caustic losses, reduce soda consumption, and lower operating costs. This is particularly important when processing fine or reactive bauxites, which tend to generate slow-settling muds.

Another major application of ALCLAR HP-21 is in mining and mineral processing, especially in tailings thickening and water clarification. In tailings thickeners, the product is used to flocculate fine particles such as clays, silica, iron oxides, and aluminosilicates. The resulting large flocs settle rapidly, allowing higher solids throughput and producing clearer overflow water. This clarified water can be recycled back into the process plant, reducing freshwater demand and supporting sustainable water management practices. In some operations, ALCLAR HP-21 is also used to improve feed conditions for filtration, resulting in higher filtration rates and lower residual moisture in filter cakes.

In industrial wastewater treatment, ALCLAR HP-21 is applied where effluents contain predominantly inorganic suspended solids. Typical industries include metal processing, power generation, coal washing, cement production, and chemical manufacturing. When dosed into clarifiers, lamella settlers, or dissolved air flotation (DAF) systems as a flocculation aid, ALCLAR HP-21 enhances particle aggregation and accelerates settling or separation. This leads to reduced turbidity, lower total suspended solids (TSS), and improved compliance with environmental discharge regulations.

ALCLAR HP-21 also finds application in sludge thickening and dewatering, particularly for mineral or chemically generated sludges. Examples include lime sludge, metal hydroxide sludge, dredging sediments, and some industrial clarifier underflows. In gravity thickeners, the polymer improves solids capture and increases sludge concentration. When used upstream of belt presses, filter presses, or centrifuges, it improves floc structure and drainage characteristics, resulting in higher cake solids and reduced sludge disposal volumes. Although cationic polymers are preferred for biological sludges, anionic polymers like ALCLAR HP-21 are highly effective for inorganic and high-ash sludges.

Another important application is in process water clarification and recycling systems. ALCLAR HP-21 is used in settling ponds, cooling water circuits, and recycled process water systems to remove fine suspended solids that can cause abrasion, scaling, or fouling of equipment. By improving water clarity, it helps maintain stable operation of pumps, heat exchangers, and pipelines while extending equipment service life.

From an operational standpoint, ALCLAR HP-21 is typically supplied as a dry powder or emulsion that must be properly diluted and hydrated before use. Correct polymer make-down, aging time, and dosing control are critical to achieving optimal flocculation performance. When applied under appropriate mixing and shear conditions, ALCLAR HP-21 delivers consistent floc size, strong settling behavior, and stable clarification across a wide range of process conditions.

In summary, ALCLAR HP-21 is a versatile and high-efficiency anionic polyacrylamide used primarily in alumina refining (red mud settling and washing), mining tailings thickening, industrial wastewater clarification, sludge thickening, and process water recycling. Its ability to improve settling rates, enhance overflow clarity, increase underflow density, and maximize water recovery makes it an essential flocculant for modern mineral-based and heavy industrial applications.