concentration of ores

One of the processes used for concentration of ores is Froth floatation process. This process is generally used for concentration of sulphide ores. Sometimes in this process we add NaCN as a depressant. NaCN is generally added in case of ZnS and PbS minerals. what is the purpose of addition of NaCN during the process of Froth floatation?

Which of the following are method of concentration of ore is metals?

Benefication of the ore can be done by different ways. It is increasing the concentration of ore by removing impurities, while refining is the process by which concentration of metal is incresed in the final product. The phase principle to apply vapour phase refining is/are:

Benefication of the ore can be done by different ways. It is increasing the concentration of ore by removing impurities, while refining is the process by which concentration of metal is incresed in the final product. The liqation process is applicable for:

Benefication of the ore can be done by different ways. It is increasing the concentration of ore by removing impurities, while refining is the process by which concentration of metal is incresed in the final product. Which of the following compound will be reduced by carbon reduction?