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Our pure calcium hydroxide products are engineered for precision performance in water treatment and purification systems — delivering reliable pH adjustment, softening, and contaminant removal at industrial scale.
Pure Calcium Hydroxide — commonly known as slaked lime or hydrated lime, with the chemical formula Ca(OH)₂ — is one of the most widely used alkaline compounds in water treatment and environmental engineering. Produced by adding water to calcium oxide (quicklime), it forms a fine white powder with high reactivity, moderate solubility, and strong alkalinity (pH ~12.4 in saturated solution). These properties make it uniquely suited for a broad spectrum of water purification challenges, from municipal drinking water systems to complex industrial effluent treatment.
Unlike synthetic alternatives, calcium hydroxide is derived from abundant natural limestone, making it cost-efficient, globally available, and environmentally compatible. Its dual capability — acting as both a pH-raising agent and a precipitating reagent — gives water engineers a single, versatile tool to address multiple water quality parameters simultaneously.
White crystalline powder with molecular weight 74.09 g/mol. Slightly soluble in water (1.73 g/L at 20°C), producing a strongly alkaline solution ideal for neutralization and precipitation reactions in water systems.
Useen supplies industrial-grade (≥90% purity), food-grade, and water-treatment-certified calcium hydroxide, each meeting stringent international standards such as NSF/ANSI 60 for drinking water chemical additives.
Manufactured from abundant natural limestone via an energy-efficient calcination and hydration process. Compared to caustic soda (NaOH), Ca(OH)₂ offers a significantly lower cost per unit of alkalinity while introducing beneficial calcium ions into treated water.
Ca(OH)₂ is the reagent of choice for raising pH in acidic water streams. Its controlled dissolution rate allows precise dosing in both batch and continuous-flow systems, preventing over-dosing and maintaining optimal alkalinity for downstream disinfection processes.
In the classic lime-soda softening process, calcium hydroxide reacts with dissolved calcium bicarbonate and magnesium salts to precipitate CaCO₃ and Mg(OH)₂, dramatically reducing water hardness. This is critical for boiler feed water, cooling towers, and municipal supply systems.
Raising pH with Ca(OH)₂ causes dissolved heavy metals — including lead, cadmium, chromium, zinc, nickel, and copper — to precipitate as insoluble hydroxides. This is a foundational step in treating industrial wastewater from electroplating, mining, and metal-finishing operations.
At elevated pH (above 10), calcium ions from dissolved Ca(OH)₂ react with orthophosphates to form insoluble hydroxyapatite (Ca₅(PO₄)₃OH), enabling highly effective biological phosphorus polishing in municipal wastewater treatment plants and agricultural runoff management.
Excess fluoride in groundwater is a global health concern. Calcium hydroxide treatment precipitates fluoride as calcium fluoride (CaF₂), reducing concentrations to WHO-recommended levels (<1.5 mg/L). This defluoridation process is widely used in India, Africa, and parts of Asia.
Lime addition increases the Langelier Saturation Index (LSI) of treated water, promoting the formation of a thin protective CaCO₃ scale on pipe walls. This passivation layer significantly reduces lead and copper leaching in aging water distribution infrastructure.
Lime stabilization of biosolids uses Ca(OH)₂ to raise sludge pH above 12, inactivating pathogens (including Salmonella and E. coli), suppressing odors, and reducing vector attraction. The resulting Class B or Class A biosolids can be safely land-applied as soil amendments.
Acid mine drainage, textile dyeing effluent, and chemical plant wastewater often require large-scale neutralization. Ca(OH)₂ slurry systems provide a cost-effective, high-throughput solution for continuous neutralization of strongly acidic industrial discharges.
Compared to sodium hydroxide (NaOH) and soda ash (Na₂CO₃), pure calcium hydroxide delivers up to 40–60% lower cost per equivalent alkalinity unit, introduces no sodium loading into treated water, and provides simultaneous softening and metal precipitation. Its low solubility acts as a natural buffering mechanism, making dosing control more forgiving and reducing the risk of pH overshoot in sensitive aquatic discharge environments.
The global hydrated lime market for water treatment is experiencing sustained growth, driven by tightening environmental regulations, rapid urbanization in emerging economies, and the expanding scope of industrial wastewater standards.
Global investments in drinking water and wastewater infrastructure are accelerating, particularly across Southeast Asia, Sub-Saharan Africa, and Latin America. The World Bank estimates over USD 114 billion annually is needed for water sector investment, with lime-based treatment remaining the most economically viable option for large-scale municipal systems in developing regions.
Regulatory frameworks such as the EU Water Framework Directive, US EPA effluent guidelines, and China's GB18918 wastewater standards are compelling industries to upgrade their treatment systems. Calcium hydroxide, as a proven and regulatory-compliant reagent, is seeing increased adoption in mining, power generation, steel, and chemical manufacturing sectors.
Modern water treatment plants are integrating smart lime dosing systems with real-time pH sensors, PLC controls, and AI-driven feed-forward algorithms. This trend is increasing the precision and efficiency of Ca(OH)₂ utilization, reducing chemical waste by up to 25%, and enabling remote monitoring for large-scale treatment facilities.
Emerging research into ocean alkalinity enhancement (OAE) and direct air capture (DAC) technologies is positioning calcium hydroxide as a critical material in climate change mitigation strategies. Dissolving Ca(OH)₂ in seawater increases its CO₂ absorption capacity, opening a new, large-scale demand vector for high-purity lime products.
Zero Liquid Discharge technology, which eliminates all liquid effluent from industrial processes, relies heavily on lime softening as a pre-treatment step before membrane systems (RO/NF). As ZLD adoption grows in water-scarce regions and semiconductor/pharmaceutical manufacturing, demand for high-purity Ca(OH)₂ is projected to rise significantly.
Research is actively exploring the role of lime-based treatment in addressing emerging contaminants. High-pH lime treatment combined with coagulation shows promise for enhancing PFAS (per- and polyfluoroalkyl substances) removal efficiency, positioning Ca(OH)₂ as a component in next-generation multi-barrier water treatment trains.
Mining operations generate highly acidic, metal-laden drainage that can devastate ecosystems. Ca(OH)₂ is the primary reagent in active AMD treatment systems, neutralizing sulfuric acid and co-precipitating iron, aluminum, and manganese. High-density sludge (HDS) processes using lime achieve superior sludge compaction, reducing disposal volumes by up to 70% compared to conventional systems.
Coal-fired power plants generate FGD wastewater rich in selenium, boron, mercury, and chlorides. Lime precipitation is the first stage in multi-step FGD wastewater treatment trains, removing selenium via co-precipitation with iron hydroxide at elevated pH, and enabling subsequent biological or physical-chemical polishing steps to meet stringent discharge limits.
Ultra-pure water systems in pharmaceutical and semiconductor manufacturing require stringent pre-treatment. Lime softening removes hardness ions that would foul RO membranes and ion exchange resins, extending membrane life by 30–50% and reducing total cost of ownership for high-purity water production systems.
In arid and semi-arid regions, irrigation water often contains elevated bicarbonate and hardness levels that degrade soil structure over time. Lime treatment of irrigation water sources, combined with gypsum application, helps maintain optimal soil pH and permeability, improving crop yields and long-term agricultural land productivity.
Large municipal utilities serving hard-water regions employ lime-soda softening plants processing millions of gallons per day. The Hoover process and its modern variants use Ca(OH)₂ addition followed by recarbonation to produce finished water with ideal hardness levels (80–120 mg/L as CaCO₃), reducing scaling in household appliances and improving consumer acceptance.
Anaerobic digestion processes for organic waste treatment require careful pH management to maintain methanogenic microbial activity. Ca(OH)₂ addition provides gentle, buffered alkalinity adjustment without the sodium toxicity risk associated with NaOH, supporting stable biogas production and improving volatile solids reduction efficiency in large-scale digesters.
Shandong Useen Calcium Co., Ltd. specializes in a range of products, including nano-scale calcium carbonate, food-grade calcium carbonate, calcium oxide, calcium hydroxide, and light calcium carbonate. Our company owns 17 fully automated calcium oxide production lines, three calcium hydroxide production lines, and nine calcium carbonate production lines.
Innovation is at the core of everything we do. In recent years, we have made significant investments in R&D, focusing on the development of new technologies and next-generation calcium products.
Our company has established close "industry-university-research" cooperation relationships with well-known foreign industry experts, the Institute of Process Engineering of the Chinese Academy of Sciences, Tsinghua University, China University of Geosciences, Beijing University of Science and Technology, Shandong University, and more. Through our industry-university-research partnerships, we have established strong capabilities in applied research, product development, and advanced process engineering.
These collaborations allow us to continuously evolve, improve our formulations, and meet the changing demands of global industries. Our company is the first in China to apply nano calcium carbonate to PE blow molding products, which can replace traditional filling materials and has excellent performance. This same spirit of innovation drives our development of ultra-high-purity calcium hydroxide grades optimized specifically for water treatment, environmental remediation, and emerging carbon capture applications.
Our materials are used across a wide range of industries including PVC pipes, automotive primers, paper, printing inks, wires and cables, sealants, rubber products, tyres, and more. Our clients rely on us for consistency, tailored solutions, and support in scaling their operations without compromising on quality.
Our company is the first in China to apply nano calcium carbonate to PE blow molding products, which can replace traditional filling materials and has excellent performance. Beyond calcium carbonate, our calcium hydroxide product line serves critical functions in water treatment plants, environmental remediation projects, food processing facilities, and chemical manufacturing operations worldwide. Whether you require bulk industrial supply or specialty high-purity grades, Useen delivers consistent quality backed by our vertically integrated production infrastructure and dedicated technical support team.
From nano calcium carbonate to food-grade slaked lime, our complete portfolio supports diverse industrial and environmental applications across the globe.
Precipitated Calcium Carbonate (Plastic)
Ground Calcium Carbonate (Printing Ink)
Ground Calcium Carbonate (Toothpaste)
Nano Calcium Carbonate (Plastic Masterbatch)
Ground Calcium Carbonate (Coating, Painting)
Ground Calcium Carbonate (Paper)
Precipitated Calcium Carbonate (Rubber)
Food grade Slakedlime（calcium hydroxide）