Lime plays a key role in the non-ferrous mining industry, particularly in ore beneficiation of copper, alumina, gold, nickel, zinc, cobalt and lead.
Adjust pH – alkaline conditions
Lime provides the alkaline conditions necessary to indirectly facilitate copper, zinc or lead flotation and depress the flotation of ore impurities. It is widely used in the gold ore beneficiation process, commonly conducted by cyanide leaching. The main role of lime is to ensure the required pH level of > 11 to avoid the volatilization and loss of the pregnant cyanide solution.
Lime slurry optimizes digestion and filtration operations in the bauxite-to-alumina Bayer process.
Other refining treatments that require lime:
Flux & Purify
In copper smelters, lime as a fluxing agent. Lime acts also as a reagent to treat gases coming from metal tapping operations. Lime acts as a reagent to remove Arsenic from copper in converters or anode furnaces.
For the magnesium refining, Lhoist has developed anhydrous high quality fluxes, used to purify by collecting impurity inclusions from scraps in the re-melting process and separate them from the clean metal.
Cover and protect
Anhydrous products are used to cover and protect molten magnesia from oxidation. This same functionality makes them useful an extinguisher of magnesium fire as they form a molten layer on the liquid magnesium, excluding oxygen.