A method for solution mining nahcolite, capable of extracting nahcolite from geological formations lean in nahcolite comprising injecting high pressure water (which may include recycled aqueous solution of bicarb and sodium carbonate) at a temperature of at least 250° F. into the formation, dissolving nahcolite in the hot water to form a production solution and recovering the production solution. The invention also includes the processing of the production solution to provide sodium carbonate and, optionally, sodium bicarbonate, comprising: decomposing the sodium bicarbonate portion of the hot aqueous production solution to form a hot aqueous solution of sodium carbonate; evaporating water from the hot aqueous solution comprising sodium carbonate to form a concentrated solution of sodium carbonate; producing sodium carbonate monohydrate from the concentrated solution of sodium carbonate by crystallization; and dewatering and calcining the sodium carbonate monohydrate to produce anhydrous sodium carbonate.

Sodium carbonate and sodium bicarbonate production from nahcolitic oil shale

A process for leaching a value metal from a base metal sulfide ore, comprising the step of leaching the ore with a lixiviant comprising a chloride, an oxidant and hydrochloric acid is disclosed. The leaching is controlled, by use of low concentrations of hydrochloric acid and a redox potential, to effect formation of hydrogen sulfide from the base metal sulfide ore. The hydrogen sulfide is stripped from the leach solution, thereby reducing the amount of sulfate generated in the leach to very low levels. The leaching may also be conducted to limit the co-dissolution of platinum group metals and gold with the base value metals. The leach forms a value metal-rich leachate and a solids residue. The solids residue may be subsequently leached to recover the platinum group metals and gold. The value metal-rich leachate can be oxidized and neutralized to recover the value base metals. In an embodiment, the chloride is magnesium chloride and lixiviant solution is regenerated.

A process for the recovery of value metals from base metal sulfide ores

An apparatus and a process for producing zinc oxide from a zinc-bearing material are provided. The process comprises the steps of leaching the complex sulfide material with hydrochloric acid, ferric chloride, and oxygen; precipitating iron from the leach solution using lime and oxygen; removing copper, silver, cadmium, cobalt and lead from the leach solution by cementation with zinc dust; precipitating zinc oxide from the leach solution using lime; and regenerating HCI from a calcium chloride leach filtrate solution to regenerate hydrochloric acid and precipitate gypsum. Related processes for recovering copper, silver, lead, and iron from complex sulfide materials and for recovering lead from residue by solubilizing lead chloride and precipitating it with lime are also provided.

Production of zinc oxide from complex sulfide concentrates using chloride processing

A process for recovering a precious metal from a sulfidic material comprises the steps of preparing an acidic aqueous halide solution having an oxidation potential sufficient to oxidise the sulfidic material and render the precious metal soluble in the solution, adding the material to the acidic aqueous halide solution so that the sulfidic material is oxidised and the precious metal is solubilised and separating the precious metal from the oxidised sulfidic material. In addition, a process for removing a contaminant from a contaminated sulfidic material comprises the steps of mixing the material in an aqueous solution wherein a multi-valent species of a relatively high oxidation state oxidises the contaminant to render it soluble in the solution, produces a contaminant refined material, and is reduced to a relatively lower oxidation state; and removing the contaminant from the solution whilst regenerating the multi-valent species to its relatively high oxidation state.

Recovering metals from sulfidic materials

A process for forming useful sodium salts by uniquely processing dilute mine brines obtained by solution mining of a sodium bicarbonate containing ore deposit with an aqueous solvent is disclosed. The dilute mine brine is reduced in sodium bicarbonate content to prevent precipitation of the sodium bicarbonate in subsequent crystallization of sodium carbonate decahydrate. The reduced mine brine is directed to a crystallizer operated to form pure sodium carbonate decahydrate crystals and a carbonate/bicarbonate containing mother liquor in which the bicarbonate content is less than 4.5% by weight. The mother liquor is then steam stripped to convert a portion of the dissolved sodium bicarbonate in the mother liquor to sodium carbonate to form a carbonate enriched brine. The carbonate enriched brine is then recycled as a portion of said aqueous solvent to be used in the solution mining of the ore deposit.

Production of sodium carbonate from solution mine brine

A hydrometallurgical process for the separate recovery of non-ferrous, ferrous, and precious metal values and sulfur from metal sulfide ore concentrates by leaching of metal sulfides with a lixiviant containing ferric chloride, cupric chloride and chlorine, precipitating cuprous chloride from the leach solution with butadiene, separating and decomposing the formed addition compound to recover the cuprous chloride, oxidizing and hydrolyzing the cuprous chloride to precipitate cupric oxychloride, converting the cupric oxychloride to cupric oxide, and reducing the cupric oxide with hydrogen for the recovery of copper. The leach residue is treated for the recovery of elemental sulfur and gold. Brine solution resulting from the conversion of cupric oxychloride to cupric oxide is electrolyzed for the production of sodium hydroxide for the cupric oxychloride conversion, hydrogen for the cupric oxide reduction and chlorine, which is partly used in the recovery of gold and partly recycled to the concentrate leach. Silver is recovered as silver iodide from the mother liquor from the cuprous chloride precipitation with butadiene. A portion of the solution from the silver recovery is treated for recovery of Cu, Zn, Co and Ni, and the remaining portion and residual solution from Cu, Zn, Co and Ni recovery are treated with oxygen at elevated temperature and pressure for the regeneration of ferric chloride and precipitation of excess iron as anhydrous ferric oxide.

Hydrometallurgical process for recovering copper and other metal values from metal sulphides

Mined salt mixtures comprising sodium-carbonate, -bicarbonate, -chloride, -sulfate, and -double salts, such as trona and burkeite, are leached with a bicarbonate-saturated solution and added carbon dioxide to selectively dissolve the sodium chloride, sodium sulfate and burkeite and to precipitate additional trona, leaving a leach residue consisting essentially of trona. The trona is calcined and dissolved, and the carbonate solution is purified, crystallized and dehydrated in a non-convective solar pond yielding high purity sodium carbonate monohydrate which is converted into dense soda ash. The brine solution from the leach may be treated for the recovery of a further amount of trona.

Process for the recovery of sodium carbonate from salt mixtures

A process for treating thermally activated metal sulfides containing copper, iron and zinc for separate recovery of zinc as zinc sulfide in which the metal sulfides are subjected to a two-stage countercurrent acid leach for the formation of copper sulfide containing acid leach residue and ferrous sulfate solution. The second-stage acid leach is performed in two steps; the first step is operated at a relatively high pulp density and high acid concentration for iron and zinc extraction, the resulting slurry diluted, and the second step is operated at a relatively low pulp density and low acid concentration for dissolution of precipitated ferrous sulfate and precipitation of any dissolved copper values by H 2 S. The diluent solution for the slurry from the second-stage first step preferably is generated sulfuric acid solution from a jarosite precipitation and iron and zinc-containing solution from a subsequent activation leach. Zinc in solution from the acid leach and activation leach is precipitated as zinc sulfide in substantially pure form.

Process for recovery of copper and zinc from complex sulphides

A hydrometallurgical process for treating iron containing metal sulfides for rendering iron and non-ferrous metal values active and amenable for selective extraction and separate recovery. Sulfur values can be controllably produced as elemental sulfur or as sulfuric acid to supply acid requirements of the process, while substantially obviating the discharge of sulfur-containing gases to the atmosphere. Ores and concentrates of the sulfides are thermally activated by sequentially heating and reducing said sulfides in a countercurrent flow of heating and reducing gases respectively in a reactor whereby the reaction products of the reducing gas and sulfides, together with liberated labile sulfur, are controllably combusted with oxygen to satisfy heat requirements of the thermal activation process and to convert sulfur values to SO2 gas. The activated sulfides are subjected to an acid leach in aqueous sulfuric acid for production of ferrous sulfate and evolution of H2 S gas which are separated from the solid sulfide residue containing concentrated non-ferrous metal values. The ferrous sulfate is oxidized and hydrolysed to precipitate the iron, which is removed from the system, and to regenerate sulfuric acid. At least a portion of the SO2 gas from said heating step and at least a portion of the H2 S from the acid leach are converted to sulfuric acid to satisfy the acid requirements of the process, and remaining SO2 is combined and catalytically reacted with remaining H2 S to produce elemental sulfur. The solids residue from the acid leach is subsequently subjected to further treatment for recovery of metal values.

Production of copper and sulfur from copper-iron sulfides

A process for the treatment of complex lead sulfide-containing concentrates additionally containing at least one metal of the group consisting of iron, copper, zinc, silver, arsenic, antimony, bismuth and gold which comprises the steps of selectively leaching a concentrate with iron-containing lixiviant for converting lead sulfide in said concentrate to lead chloride and forming a leach residue and a leach solution, subjecting said lead chloride in the leach residue to a two-stage, countercurrent, hot brine leach to dissolve the lead chloride in a brine-leach solution, subjecting the brine leach solution to crystallization by evaporative cooling for the separate recovery of crystallized lead chloride, residual brine and crystallization condensate, and returning said residual brine to said brine leach, subjecting crystallized lead chloride in admixture with sodium chloride to electrolysis in a fused bath for production of lead and evolution of chlorine, absorbing chlorine in a first portion of said leach solution for the generation of ferric chloride-containing solution; and treating a second portion of said leach solution for the recovery of values. The iron-containing lixiviant comprises an aqueous solution of ferric chloride in a concentration in the range of from 100 to 200 g/l ferric ion or aqueous solutions of ferrous chloride and hydrochloric acid in concentrations in the range of 25 to 160 g/l ferrous chloride and of 60 to 120 g/l hydrochloric acid.

Godefridus M. Swinkels

Papers

Hydrometallurgical process for recovering copper and other metal values from metal sulphides

Process for the recovery of sodium carbonate from salt mixtures

Process for recovery of copper and zinc from complex sulphides

Production of copper and sulfur from copper-iron sulfides

Hydrometallurgical process for treating metal sulfides containing lead sulfide