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.

Description

FIELD OF THE INVENTION[0001]This invention relates to the drying of copper concentrates in a gas suspension or fluid bed dryer. In one aspect, this invention relates to a process for the drying of copper concentrate that is both energy efficient and that reduces the possibility of concentrate combustion in the dryer.BACKGROUND OF THE INVENTION[0002]Present copper production from sulfide ores almost universally involves mining porphyry deposits composed mostly of chalcopyrite (Cu.FeS2). Raw ore is crushed and ground suitable for floatation concentration in which different materials are separated by agitating a pulverized mixture of the materials with water, oil, and chemicals. Differential wetting of the particles suspended during flotation causes unwetted particles to be carried by air bubbles to the surface for collection to produce a beneficiated ore containing about 25% copper and approximately equal portions of copper, iron, and sulfur. The concentrate is dewatered mechanically ...

AI Technical Summary

Benefits of technology

[0007]In a first embodiment of the invention waste nitrogen from the oxygen plant is directed to a hot gas generator, in the presence of heated ambient air, thereby substantially reducing the oxygen content of the preheated ambient air in the hot gas generator. The oxygen depleted ambient air and the heated nitrogen gas are directed to a fluid bed or gas suspension device where they are mixed with and dry wet concentrate. The dried concentrate is carried out of the device with the spent nitrogen and ambient air and is collected for further treatment.

[0008]In another embodiment of the invention removing the oxygen source eliminates the possibility of concentrate combustion in the dryer. Waste nitrogen from the oxygen plant is directed to an air to gas heat exchanger. A hot gas generator fires the heat exchanger. However, the ambient air from the hot gas generator used as the heat transfer medium is directed to atmosphere and not into the drying device. Nitrogen preheated to significantly above the concentrate ignition temperature (260° C.) is directed to a fluid bed or gas suspension device where it is mixed with and dries incoming wet concentrate. The dried concentrate is carried out of the device with the spent nitrogen and collected for further treatment.

[0009]In a third embodiment of the invention there is a method for drying copper sulfide concentrates in gas suspension and fluid bed dryers utilizing controlled sulfide ore oxidation. In this embodiment the risk of concentrate combustion is reduced by controlling the amount of oxygen utilized in the dryer. Waste nitrogen and a controlled amount of oxygen from the oxygen plant is directed to a heat exchanger and preheated to temperatures sufficient to dry the copper concentrates. The preheated oxygen and nitrogen gases are directed to a fluid bed or gas suspension device where they are mixed with incoming wet concentrate. The reactor temperature is maintained above the concentrate combustion temperature and the sulfide is allowed to oxidize in a controlled fashion—thus providing the dehydration energy without supplemental fuel firing. The dried concentrate is carried out of the device with the spent drying gasses, passes through the economizer and collected for further treatment.

[0010]The present process has the benefit of significantly reducing the combustion risk when drying sulfide concentrates in a fluid bed or gas suspension dryer. The present process also benefits from lower equipment costs due to smaller gas handling requirements and significant power savings by using waste nitrogen.

Problems solved by technology

However, the ambient air from the hot gas generator used as the heat transfer medium is directed to atmosphere and not into the drying device.

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