China Nonferrous Metallurgy

Quite a large quantity of magnesium reduction slag is generated in the Pedgeon process of magnesium smelting, during the stockpiling process of the slag, such issues as soil alkalization and hardening, etc. will arise, as for its disposal and consumption, it is mainly used for producing cement, buildinguse brick and desulfurization agent, with low comprehensive use value. The process route of ammonium chloride leaching of magnesium reduction slag are put forward. The process can be used to extract and separate calcium, silicon and other elements in the magnesium reduction slag, to make the magnesium slag become the calcium source and silicon source, so as to achieve the zero emission and high value utilization of the magnesium slag. In this paper, aiming at the leaching procedure in the process, the calcium leaching efficiency and the phase of leaching residue under various singlefactor conditions are studied, and the following conclusions are obtained: the ammonium chloride is able to make selective leaching for the calcium in the magnesium reduction slag, the leaching efficiency is closely related to reacting temperature, ammonium chloride concentration, liquidsolid ratio, etc.; the leaching efficiency increases with the increase of ammonium chloride concentration and liquidsolid ratio, it increases first and then decreases with the rising temperature; the better leaching process conditions are as follows: reacting temperature of 25℃, ammonium chloride concentration of 15%, and liquidsolid ratio of 40∶1, under which, the calcium leaching efficiency can be as high as 88.7%; the phase of the leaching residue is mainly composed of magnesium oxide, calcium carbonate, silicon dioxide and other substances, from which the purer siliconbearing raw material can be got by scrubbing process.