|Freeze Conditioning of Minerals:
Minerals, particularly coal, as they are normally transported and handled, contain substantial amounts of moisture. If shipped or stored in cold weather of sufficient duration and intensity, moist minerals tend to freeze. Frozen minerals create severe handling problems during the winter months. For example, bottom-dumped railcars that unload in a few minutes in the summer months may take hours to unload when frozen. The use of freeze conditioning agents (FCA) to ease unloading and handling of minerals during the winter months has become an accepted practice by the mineral industry.
FCAs have two main benefits. They function as a freeze point depressant, and also weaken the crystal structure of the ice formed, making the ice more friable. Calcium chloride, being an excellent additive to weaken the crystal structure of the ice and superior as a freeze point depressant, is widely used in the mineral industry as a freeze conditioning agent.
The amount of calcium chloride required depends on the expected weather condition and the moisture content of the minerals. For coal, with the moisture content of coal being about 10 wt%, the amount required could be 1-2 litres per ton of coal.
Dust Control in Mining Operations:
Both underground and open cut mining operations are regulated for the level of dust emission in the working environment. Since April 2, 1998, according to the Mine Safety and Health Administration (MSHA) in the U.S.A. a noncompliance determination is based on the results of single full-shift dust samples taken by the inspectors. MSHA requires mine operators to take corrective action to lower the concentration of respirable dust whenever a full-shift measurement by an MSHA inspector indicates non-compliance.
Calcium chloride, being hygroscopic and deliquescent, when spread on the haulage roads minimizes the dust emission. It is also very cost effective.
Calcium chloride is also used in mining operations for the stabilization of the unpaved haulage roads, as its application improves the strength of the road surface. Apart from keeping the dust level down, its use also substantially reduces the overall road maintenance cost.