solutions

HENGFENG Floc Application Process of Flocculant (PAM) in Heavy Metal-Contaminated Soil Leaching Remediation 1. Pretreatment: Wastewater pH Adjustment and Homogenization Purpose Citric acid is acidic (pH ≈ 2-3), while polyacrylamide (PAM), especially HENGFENG Floc non-ionic or HENGFENG Floc anionic types, exhibits optimal flocculation performance under neutral to weakly alkaline conditions. Meanwhile, pH adjustment can disrupt part of the heavy metal-citric acid complexes, releasing free heavy metal ions (e.g., Co²⁺) or forming hydroxide/carbonate micro-precipitates, thereby creating favorable conditions for subsequent flocculation. Operation Add quicklime (CaO) or sodium hydroxide (NaOH) into the leachate storage tank to adjust the pH to 7.0-8.5, with real-time monitoring via an online pH meter. Simultaneously, start the agitator at a rotational speed of 150-200 r/min to homogenize the wastewater, preventing local pH fluctuations from affecting flocculation efficiency. 2. PAM Selection and Dissolution Preparation Selection Basis The wastewater in this case contains negatively charged soil colloids (due to the negative charge on the surface of soil clay minerals) and heavy metal complexes (mostly negatively charged or neutral). Therefore, anionic PAM (with a molecular weight of 8-12 million Da) is preferred. The carboxyl groups (-COO⁻) on its molecular chains can promote agglomeration through "charge neutralization" (adsorbing negative charges on the surface of soil colloids) and "bridging effect" (connecting multiple micro-particles). Compared with HENGFENG Floc  non-ionic PAM, it has higher flocculation efficiency, and its cost is lower than that of HENGFENG Floc cationic PAM. Dissolution Preparation Dissolution Water: Use deionized water or clarified tap water (to avoid precipitation caused by the reaction of Ca²⁺ and Mg²⁺ in hard water with PAM). Concentration Control: Mix HENGFENG Floc PAM powder with water at a mass ratio of 0.1%-0.3%, i.e., add 1-3 g of HENGFENG Floc PAM to 1 L of water. Dissolution Method: First add water into the stirring tank, then slowly sprinkle PAM powder (to prevent caking). Control the stirring speed at 80-100 r/min and the stirring time at 30-60 minutes until the solution becomes transparent and viscous (with no visible particles to the naked eye). If dissolution is insufficient, undissolved PAM particles will form "fish eyes" in the wastewater, which will instead reduce flocculation efficiency. 3. PAM Dosing and Reaction (Flocculation Reaction Tank) Dosing Method Adopt "metering pump dripping" to slowly inject the prepared PAM solution into the flocculation reaction tank at a final dosage of 1-5 mg/L (i.e., 1-5 mg of effective PAM component per liter of leachate). The dosing port is installed in front of the stirring impeller to ensure rapid mixing with the wastewater. Reaction Control (Two Stages) Rapid Mixing Stage: Control the stirring speed at 200-300 r/min for 1-2 minutes. The purpose is to achieve instant and uniform contact between the PAM solution and the wastewater, enabling PAM molecules to quickly adsorb onto the surface of colloidal particles. Slow Flocculation Stage: Reduce the rotational speed to 50-80 r/min and maintain it for 10-15 minutes. This stage is critical for "bridging and agglomeration". Slow stirring can avoid damaging the flocs being formed, allowing small particles to gradually aggregate into large flocs (visible "alum flowers") with a particle size of ≥ 100 μm. Meanwhile, the flocs can adsorb cobalt complexes or free Co²⁺ in the wastewater. 4. Solid-Liquid Separation (Sedimentation Tank / Clarification Tank) Process Selection Due to the high density of the flocs (containing heavy metal precipitates), vertical flow sedimentation tanks or inclined tube sedimentation tanks are adopted, as they occupy less area and have higher separation efficiency. Operating Parameters Control the hydraulic retention time (HRT) of the sedimentation tank at 1-2 hours and the upward flow velocity at 1.5-2.5 mm/s. This ensures that the flocs have sufficient time to settle to the bottom of the tank, forming "sludge" (containing heavy metal precipitates, soil colloids, and PAM flocs), while the upper layer becomes clarified liquid. Key Function Through this step, the removal rate of suspended solids (SS) in the wastewater can reach over 90%. At the same time, heavy metals such as cobalt settle along with the flocs, significantly reducing the heavy metal concentration in the clarified liquid and laying a foundation for subsequent up-to-standard discharge or advanced treatment. 5. Subsequent Treatment: Disposal of Sludge and Clarified Liquid Sludge Treatment The heavy metal-containing sludge at the bottom of the sedimentation tank (with a moisture content of approximately 80%-90%) is transported to a plate-and-frame filter press via a sludge pump for dewatering, forming sludge cakes with a moisture content of ≤ 60%. These sludge cakes must be managed as hazardous waste and sent to qualified institutions for solidification/stabilization treatment or cobalt recovery (e.g., through pyrometallurgical smelting or hydrometallurgical leaching). Clarified Liquid Treatment The upper clarified liquid needs to be tested for pH, chemical oxygen demand (COD, caused by residual citric acid), and heavy metal concentrations (e.g., Co, As, Cu). If it meets the standards (e.g., cobalt concentration < 0.01 mg/L, in line with the Environmental Quality Standards for Surface Water (GB 3838-2002)), it can be directly discharged. If it fails to meet the standards, further advanced treatment using ion exchange resins or membrane separation technology is required to ensure the complete removal of pollutants.

HENGFENG Anionic polyacrylamide emulsion is widely used in the alumina separation process. It serves as a flocculant to promote the settling of solid - liquid mixtures, improve separation efficiency, and enhance product quality. The following is a detailed introduction:     · Role in the alumina separation process: In the alumina production process, especially in the Bayer process, after bauxite is dissolved in caustic soda solution at high temperature and pressure, a large - amount of solid - liquid mixture containing red mud and aluminum - sodium solution is formed1. Anionic polyacrylamide emulsion can adsorb and bridge the fine - grained solid particles in the slurry. By adding an appropriate amount of anionic polyacrylamide emulsion to the primary thickener, the red mud particles can be aggregated into larger flocs, accelerating their sedimentation rate. This helps to obtain clear overflow liquid, reduce the loss of aluminum - sodium solution, and improve the efficiency of subsequent filtration and other operations. In addition, in the counter - current decantation process for red mud washing, anionic polyacrylamide emulsion is also used to promote the settlement of residual red mud particles, so as to recover more alumina from the solution and improve the utilization rate of resources.   · Product characteristics required: · High molecular weight: Usually, anionic polyacrylamide emulsion with a high molecular weight is required. High - molecular - weight polymers can form longer molecular chains, which are more conducive to adsorbing and bridging between particles, and can form larger flocs. · Adjustable hydrolysis degree: According to different bauxite qualities and process requirements, the hydrolysis degree of anionic polyacrylamide can be adjusted. Generally, the hydrolysis degree is in the range of 6% - 45%. A suitable hydrolysis degree can ensure that the product has a good charge - density, so as to better adsorb particles with opposite charges or neutral particles through electrostatic interaction. · Good water - solubility: It can be quickly and evenly dissolved in water to form a uniform solution, so as to be effectively mixed with the alumina - containing slurry. It is usually required to be dissolved in low - hardness water, and the dissolution time is generally within 1 hour.   · Usage : · Dispersion: Efficient dispersion is very important during use. Otherwise, agglomeration and “fish eyes” will occur, and the dissolution time will be prolonged. · Water quality: Use low - hardness water, and avoid using tanks or pools that may affect water quality. · Temperature: Appropriate heating can accelerate the dissolution rate, but the water temperature should not exceed 50℃. · Stirring: Stirring can accelerate dissolution, but strong stirring will break the molecular chain of the dispersant and cause degradation. A ship - shaped agitator with a rotation speed of 200 - 500 rpm is the best. · Concentration preparation: Usually, the product is mixed into a 0.05% - 0.5% (w/w) solution for standby. · Dosage adjustment: The optimal dosage should be adjusted according to specific application conditions to achieve the best flocculation effect and economic benefits.

Application of Cationic Polymers in Municipal Sludge Dewatering - Thailand     A municipal wastewater treatment plant in Bangkok, Thailand, had been facing challenges in sludge dewatering. The plant's existing flocculants resulted in poor cake dryness and unstable dewatering performance, especially when the influent water quality fluctuated during the rainy season. This not only increased operating costs, but also brought difficulties to sludge treatment and disposal. Solution:   Hengfeng Chemical provided cationic polyacrylamide, which has a high charge density and optimized molecular weight, tailored to the characteristics of Thai municipal sludge. Our technical support team conducted a comprehensive on-site evaluation, including beaker tests and pilot tests, to optimize dosing parameters and ensure seamless integration with the plant's existing filter press system.   Results: Sludge dewatering efficiency increased by more than 35% Significantly improved sludge cake dryness, reducing transportation and landfill costs Reduce chemical consumption and improve cost-effectiveness Maintain stable performance under different wastewater qualities Make dewatering equipment run more smoothly, reduce blockage and maintenance requirements   The customer is very satisfied with the efficiency improvement and cost savings, and has adopted Hengfeng's cationic polyacrylamide as its long-term sludge treatment solution. This case shows that Hengfeng Chemical can provide targeted solutions for complex municipal challenges in Southeast Asia and other regions.

Polyacylamide Application of Polyacrylamide in Municipal Wastewater Treatment – Brazil One of the municipl wastewater treatment plant in São Paulo faced challenges with suspended solids, high turbidity, and inefficient sludge dewatering. Their previous flocculant required a high dosage and resulted in inconsistent treatment results, increasing operating costs. Solution:Hengfeng Chemical supplied a customized anionic polyacrylamide with a medium molecular weight and appropriate charge density for the local water conditions. Our technical team guided the on-site trial and optimized the dosage based on jar tests and flow rates. Results: Improved solid-liquid separation efficiency by over 30% Reduced sludge volume, cutting disposal costs Lower chemical consumption compared to the previous product Stable treatment performance, even during rainy season The client was highly satisfied with the results and continues to use Hengfeng PAM in their daily operations. This case highlights the adaptability and effectiveness of our polyacrylamide products in diverse municipal applications worldwide.

Cross - link emulsion can improve the treatment efficiency of municipal wastewater through several mechanisms, mainly by enhancing coagulation - flocculation, improving adsorption capacity, and optimizing membrane separation. The details are as follows: Enhancing coagulation - flocculation: Bridging effect: The cross - linked polymer chains in the cross - link emulsion can adsorb onto the surface of fine suspended particles in the wastewater. They act as bridges, connecting different particles together. This causes the fine particles to aggregate into larger flocs, which are easier to separate from the water. As a result, the sedimentation or filtration processes can more effectively remove these flocs, reducing the turbidity and suspended solids content in the wastewater. Charge neutralization: Many cross - link emulsions carry certain charges. They can interact with the charged particles in the wastewater, neutralizing their charges. This reduces the electrostatic repulsion between the particles, allowing them to come closer together and aggregate more easily. This charge - neutralizing effect helps to improve the coagulation process and promotes the formation of larger and denser flocs. Improving adsorption capacity: Large specific surface area: The cross - linked structure of the emulsion provides a large specific surface area. This allows more sites for the adsorption of pollutants. For example, organic pollutants, heavy metal ions, and other substances in the wastewater can be adsorbed onto the surface of the cross - link emulsion particles. The larger the specific surface area, the more pollutants can be adsorbed, thereby reducing the concentration of pollutants in the wastewater. Selective adsorption: Depending on the chemical composition and structure of the cross - link emulsion, it can have a certain degree of selectivity for different pollutants. Some cross - link emulsions can be designed to have specific functional groups that have a strong affinity for certain types of pollutants. This enables them to preferentially adsorb those pollutants, improving the efficiency of removing specific contaminants from the wastewater. Optimizing membrane separation: Antifouling properties: When used in membrane separation processes, cross - link emulsions can be coated on the membrane surface. This coating can reduce the adhesion of pollutants to the membrane. The cross - linked polymer chains form a protective layer that prevents the deposition of organic matter, bacteria, and other foulants on the membrane surface. As a result, the membrane's permeability and separation efficiency are maintained for a longer period, reducing the frequency of membrane cleaning and replacement. Improved membrane performance: The cross - link emulsion can also improve the hydrophilicity of the membrane. This makes it easier for water molecules to pass through the membrane, increasing the water flux. At the same time, it can enhance the mechanical strength of the membrane, making it more resistant to the pressure and shear forces in the filtration process. This helps to maintain the integrity and stability of the membrane, ensuring the high - efficiency operation of the membrane separation process.

At Jiangsu Hengfeng Fine Chemical Co., Ltd., we specialize in producing high-quality polyacrylamide (PAM),  can be applied in the mining,processing and tailing disposal process of mines such as coal, gold, silver, copper, iron, lead and zinc, aluminium, uranium, nickel, phosphorus, potassium, manganese and other minerals.Its main purpose is to improve the efficiency of the solid-liquid separation and recovery rate.Copper MiningThe pulp or tailings from the flotation cell need enter into thickening tank for further settlement. Flocculant can be fed for the promoting of subsidence and obtaining of overflow. The gained overflow can serve as circulating water.The remaining concentrated tailings will be pumped into the centrifugal for centrifuge dewatering,in which anionic polyarylamide as centrifugal additives is utilized. Anionic polyacrylamide flocculant is used to improve the efficiency of sedimentation and filtration. The concentrate of copper gained from cleaned mine or filter cake is 25% to 35%. It will be recovered through high temperature metallurgy.Coal WashingFlotation process is usually adopted to gain cleaned coal with high combustion value.Since the difference in proportion between coal particle and impurity in water,coal mine will float on the surface of the water while the impurity will percipitate at the bottom of the container.Cleaned coal is obtained after further process.In the above process,impurity can be removed and water can be recycled.Polyacrylamide can function as a flocculant to improve the seperation efficience of water and impurity.Nickel MiningIn the "wet" process,feeding PAM can get a quick water-mud separation effect when separate nickel from nickel mine.Lead and Zinc MiningMinerals can be oxidized to zinc oxide by calcination.Next,feed sulfuric acid to dissovle the oxide and filter.All the cleaned mines can be dissolved in acid with PH around 5 or 2.5.In lead and zinc filtering process, the use of anionic polyacrylamide flocculant can effectively promote the rapid subsidence of mineral and the clarification of the filtrate and improve the production efficiency of the process, reduce the loss of minerals.Gold and Silver MiningAfter the mine is grinded, anionic polyacrylamide flocculant can be fed to the thickener to subside the Solid content(%),and then the bottom substance can be filtered through several filters.Add polyacrylamide to the thickener before the filtration.