SHMP (Sodium Hexametaphosphate) Supplier South Africa

What Is Sodium Hexametaphosphate?

Sodium hexametaphosphate (SHMP, Na₆P₆O₁₈, Graham’s salt) is a long-chain inorganic polyphosphate — a glass-like polymer of sodium phosphate units. In solution it exists as a mixture of cyclic and linear polyphosphate chain lengths. SHMP is a powerful chelating and sequestering agent for di- and trivalent metal ions — calcium (Ca²⁺), magnesium (Mg²⁺), iron (Fe²⁺/Fe³⁺), manganese (Mn²⁺), and copper (Cu²⁺) — forming stable soluble chelate complexes that prevent these ions from forming scale deposits or precipitating as hydroxides, carbonates, or oxides.

Municipal Water Treatment and Scale Prevention

SHMP is widely used in municipal potable water treatment as a sequestrant added to drinking water to prevent red water (from iron oxide deposition) and scale formation in distribution pipework. At very low doses (0.5–5 mg/L as P₂O₅), SHMP stabilises dissolved iron and manganese in solution, preventing the pipe staining and water discolouration caused by their precipitation. In water supply systems with corrosive water, SHMP can form a mild calcium-polyphosphate passivating film on pipe surfaces, reducing corrosion. Its potable water use is regulated by NSF/ANSI Standard 60 for water treatment chemicals.

Industrial Water Treatment and Food Applications

In industrial cooling water systems, SHMP threshold-inhibits calcium carbonate and calcium sulfate scale, though it is less stable than organophosphonates at elevated temperatures (hydrolysing to orthophosphate above ~60°C). In food processing, SHMP is used as an emulsifying salt, texturising agent, and sequestrant in processed cheese, seafood, and meat products. In textile dyeing, it is used as a water softener and dye levelling agent. Terracore Chemicals supplies SHMP in water treatment and food grade for customers across Southern Africa.