Investigation into the Neutralization of Acidic Concentration Waste of Sulfide-Tungsten Ores during Their Secondary Processing

Abstract

The results of the investigation into the possibility of neutralization of concentration waste of sulfide-tungsten deposit (anthropogenic sands), which contain; in
addition to hubnerite and molybdenite remained after the partial recovery, sulfides of copper, lead, zinc, and iron; and are currently liable to secondary processing;
are presented. The pH of the aqueous extract of sands varies from 3 to 4.6 while that of recycle water participating in the production process reaches 2.5.
Natural neutralizing materials such as limestone, dolomite, volcanic and zeolite-containing tuff, and clay are investigated as reagents. The experiments on the neutralization
of sands are performed in static and dynamic conditions. When determining pH of aqueous extracts of mixtures of sand and limestone in static conditions,
it is revealed that as the volume ratio of limestone to sand increases to 1 : 30, pH increases from 4.30 to 5.75. The variation in the solution pH when passing
distilled water through a column with a mixture of anthropogenic sand with limestone or dolomite was investigated in dynamic conditions. The experimental results
revealed that acid accumulated in sands is more effectively neutralized with limestone, and the acid-basic equilibrium is attained in a range of 6.5-7.5 depending
on the component ratio. Clay and volcanic and zeolite-containing tuffs have no long-term neutralizing properties compared with limestone and dolomite. It is
revealed experimentally that it is more effective to neutralize acidic anthropogenic sands with limestone.