What to Do When Pyrite Recovery Rate Is Low？

Low pyrite recovery in flotation circuits is caused by multiple factors: insufficient mineral liberation, surface oxidation of pyrite, improper pulp pH and potential, mismatched reagent scheme and slime interference. It is necessary to sort out these influencing factors one by one instead of blindly adjusting reagent dosage. Step-by-step troubleshooting starts with ore microscopy and flotation testwork to identify the root cause of poor floatability.

If pyrite grains are locked in gangue or associated sulfides, adjust grinding fineness to improve liberation. However, over-grinding forms fine pyrite slimes which oxidize rapidly and become hydrophilic, making collection difficult. Pyrite surface oxidation is a frequent problem. Oxidized iron hydroxide film covers pyrite and prevents collector adsorption, which is very common for stockpiled ore and ore exposed in wet environment. Moderate pulp potential control and surface cleaning can restore floatability of oxidized pyrite.

Reagent optimization is critical. Xanthate collectors are the main choice for pyrite flotation; combined collectors often improve collecting performance and adapt to complex pulp conditions. Lime is a strong depressant for pyrite under high alkaline conditions. If the plant uses lime for copper-sulfur separation, excessive lime dosage will heavily suppress pyrite and reduce recovery. Adjust pH downward, add activators and optimize collector and frother dosage. Desliming before flotation reduces slime coating on pyrite surface. Rougher-scavenger circuit modification and regrinding of middlings can also recycle lost pyrite and lift the final recovery target.