Method for drying copper sulfide concentrates

Abstract

Dried copper concentrate is introduced to a smelter/converter that utilizes oxygen enrichment in the smelter/convert process. The copper concentrate was previously dried in a gas suspension or fluid bed dryer by contact with nitrogen gas that was a byproduct from the oxygen plants utilized to support the smelter.

1 . A process for drying copper sulfide concentrates in preparation for smelting the dried copper concentrates in an oxygen enriched environment, the oxygen for which is supplied by an oxygen plant that generates waste nitrogen gas, the process comprising:
 A. introducing copper concentrates into a drying chamber;   B. directing waste nitrogen gas from the oxygen plant to a heat treatment means for heating the nitrogen gas to temperatures suitable to dry the copper concentrates;   C. introducing the heated nitrogen gas into the drying chamber to thereby dry the copper concentrates to a moisture content suitable for a smelter; and   D. recovering the dried copper concentrates.   
     
     
         2 . The process of  claim 1  wherein the drying chamber is a fluid bed dryer. 
     
     
         3 . The process of  claim 1  wherein the drying chamber is a gas suspension dryer. 
     
     
         4 . The process of  claim 1  wherein the concentrate is dried in the drying chamber in the absence of oxygen. 
     
     
         5 . The process of  claim 4  wherein the nitrogen gas is heated to significantly above the copper concentrate ignition temperature. 
     
     
         6 . The process of  claim 5  wherein the nitrogen gas is heated to temperatures of from about 300° C. to about 325° C. 
     
     
         7 . The process of  claim 1  wherein the heat treatment means is a hot gas generator into which there is introduced oxygen-containing ambient air, wherein in said hot gas generator at least some of the oxygen-containing ambient air reacts with a suitable fuel to support combustion to thereby heat the nitrogen gas and deplete the oxygen in the ambient air. 
     
     
         8 . The process of  claim 8  wherein the oxygen-depleted ambient air is introduced into the drying chamber along with the heated nitrogen gas. 
     
     
         9 . The process of  claim 1  wherein the heat treatment means is a heat exchanger into which there is also delivered, from the oxygen plant, a predetermined amount of oxygen gas for heating, after which the heated oxygen gas is delivered to the drying chamber along with the heated nitrogen gas. 
     
     
         10 . The process of  claim 9  the heated nitrogen gas and oxygen gas are mixed with heated ambient air prior to being delivered to the drying chamber. 
     
     
         11 . The process of  claim 9  wherein the amount of oxygen gas delivered into the drying chamber is insufficient to support the combustion of the concentrate at its normal combustion temperature. 
     
     
         12 . The process of  claim 11  wherein the temperature in the drying chamber is maintained above the combustion temperature for the concentrate to thereby permit the sulfides in the concentrate to oxidize in a controlled fashion. 
     
     
         13 . The process of  claim 9  wherein the dried concentrate is entrained in a heated oxygen and nitrogen gas mixture that is directed to the heat exchanger and thereafter to a gas solids separator. 
     
     
         14 . A process for drying copper sulfide concentrates produced by a floatation process comprising:
 A. introducing copper concentrates into a drying chamber;   B. directing nitrogen gas heated to temperatures suitable to dry the copper concentrates into the drying chamber to thereby dry the copper concentrates to a moisture content suitable for a smelter; and   C. recovering the dried copper concentrates.   
     
     
         15 . The process of  claim 14  wherein the drying chamber is a fluid bed dryer. 
     
     
         16 . The process of  claim 14  further comprising delivering heated oxygen gas into the drying chamber in an amount insufficient to support the combustion of the concentrate at its normal combustion temperature. 
     
     
         17 . The process of  claim 16  wherein the temperature in the drying chamber is maintained above the combustion temperature for the concentrate to thereby permit the sulfides in the concentrate to oxidize in a controlled fashion.