Process for the recovery of non-ferrous metal values from sulfide ores and the reduction of gaseous emissions to the atmosphere therefrom

Claim 2

The process of claim 1 wherein the gas permeable state of the mixture is a fluidized bed.

Claim 3

The process of claim 1 wherein the gas permeable state of the mixture consists of porous pellets.

Claim 4

The process of claim 1 wherein the ratio of the weight of roasted mixture in the second stage roasting zone to that of the first stage roasting zone is from about 1:1 to about 4:1.

Claim 5

A process for roasting an admixture of sodium chloride and a copper bearing sulfide ore for subsequent extraction therefrom as a water soluble salt substantially all of the copper value therein and for reducing by at least about 85 percent the emission to the atmosphere of sulfur doixide and chlorine formed during said process without the necessity of using chemical absorbing solutions, said process comprising: I. admixing from about 30 to about 93 weight percent of a copper-bearing sulfide ore with from about 70 to about 7 weight percent of sodium chloride to form an ore-sodium chloride mixture, the quantity of air being substantially sufficient to oxidize the sulfur in the ore to the sulfate form; II. forming a fluidized bed of said mixture and heating same in a first stage roasting zone at a temperature of from about 300*C. to about 425*C., said zone being provided with from about 80 to about 140 percent of the stoichiometric quantity of air required to react with said mixture; III. conducting roasted mixture from said first stage roasting zone to a second stage roasting zone in which the temperature is maintained at from about 300*C. to about 425* C. while replenishing the first stage roasting zone with a fresh charge of said sodium chloride-sulfide ore admixture; IV. conducting exhaust gases containing a mixture of sulfur dioxide, chlorine and air from said first stage roasting zone to said second stage roasting zone to convert the copper content of the roasted mixture in said second stage roasting zone to the sulfate and chloride forms; V. trapping exhaust gases containing sulfur dioxide and chlorine in substantially equimolar quantities from said second stage roasting zone in water to form an aqueous solution of sulfuric and hydrochlorid acids thereby substantially obviating their admission to the atmosphere; and VI. leaching the roasted mixture from said second stage roasting zone with water to extract therefrom substantially all the copper value as a water soluble salt.

Claim 6

A process for roasting an admixture of sodium chloride and a copper bearing sulfide ore for subsequent extraction therefrom as a water soluble salt substantially all of the copper value and for reducing by at least about 85 percent the emission to the atmosphere of sulfur dioxide and chlorine formed during said process without the necessity of using chemical absorbing or chemical gas scrubbing solutions, said process comprising: I. admixing from about 30 to about 93 weight percent of a copper-bearing sulfide ore with from about 70 to about 7 weight percent of sodium chloride to form an ore-sodium chloride mixture; II. agglomerating said mixture to form porous pellets thereof; III. heating a charge of said porous pellets in a first stage roasting zone at a temperature of from about 300*C. to about 425*C., said zone being provided with from about 80 to about 140 percent of the stoichiometric quantity of air required to react with said mixture, the quantity of air being substantially sufficient to oxidize the sulfur in the ore to the sulfate form; IV. conducting roasted pellets from said first stage roasting zone to a second stage roasting zone in which the temperature is maintained at from about 300*C. to about 425*C. while replenishing the first stage roasting zone with a fresh charge of said sodium chloride-sulfide ore admixture; V. conducting exhaust gases containing a mixture of sulfur dioxide, chlorine and air from said first stage roasting zone to said second stage roasting zone containing roasted mixture from said first stage roasting zone to convert the copper content of said roasted mixture to the sulfate and chloride forms; VI. trapping exhaust gases containing sulfur dioxide and chlorine in substantially equimolar quantities from said second stage roasting zone in water to form an aqueous solution of sulfuric and hydrochloric acids thereby substantially obviating their admission to the atmosphere; and VII. leaching the roasted pellets from said second stage roasting zone with water to extract therefrom substantially all the copper value as a water soluble salt.

Claim 7

The process of claim 7 wherein the proportions of ore and sodium chloride are from about 25 to about 50 weight percent of ore and from about 50 to about 25 weight percent of sodium chloride, the quantity of air is from about 100 to about 120 percent of the stoichiometric quantity required, and the ratio of the quantity of roasted mixture in the second stage roasting zone to fresh ore-sodium chloride mixture in the first stage roasting zone is from about 1:1 to about 4:1.

Claim 8

A process for recovering metal values from sulfide ores which comprises: I roaSting in a first roasting zone a gas permeable admixture of from about 30 to about 93 percent of a sulfide ore containing a metal selected from the group consisting of copper, nickel, cobalt and magnanese, and from about 7 to about 70 percent of an inorganic chloride selected from the group consisting of sodium chloride, potassium chloride, lithium chloride and magnesium chloride at a temperature of from about 300*C. to the fusion point of said admixture while subjecting said admixture to a flow of air in sufficient volume to provide from about 80 to about 140 percent of the stoichiometric quantity of oxygen required to react with said admixture to oxidize same, the quantity of air being substantially sufficient to oxidize the sulfur in the ore to the sulfate form; II. removing and passing a portion of the roasted solids from said first roasting zone to a second roasting zone maintained at a temperature of from about 300*C. to the fusion point of said roasted admixture; III. conducting effluent gases containing a mixture of sulfur dioxide, chlorine and air from the first roasting zone to the second roasting zone and passing said gases through the roasted admixture contained therein to convert the copper, nickel, cobalt and manganese content of said roasted mixture to the sulfate and chloride forms; IV. recovering and removing effluent gases containing sulfur dioxide and chlorine in substantially equimolar quantities from the second roasting zone and trapping said gases in water to form a solution of sulfuric and hydrochloric acids thereby substantially obviating their admission to the atmosphere; and V. removing solid roasted mixture from said second roasting zone and leaching said roasted mixture with water to recover substantially all of said metal values, said process reducing by at least about 85 percent the emission to the atmosphere of sulfur dioxide and chlorine formed during said process.