Abstract: An aqueous polysulfide composition comprises one or more inorganic polysulfides, wherein the amount of polysulfides in the composition is at least 30% by weight, preferably at least 35% by weight, more preferably at least 40% by weight, and wherein the amount of thiosulfate anions in the composition is at most 5% by weight, relative to the total weight of the composition. In one embodiment the weight ratio of polysulfides to thiosulfates in the aqueous composition is from 55/1 to 1.5/1. In another embodiment, the aqueous polysulfide composition has a pH of at least 10. A process for preparing an aqueous polysulfide composition comprises reacting a sulfide salt (c) with elemental sulfur to form one or more polysulfide salts. The compositions have many uses and are in particular useful in metal capturing, cyanide scavenging, soil remediation, water treatment, petroleum processing, leather processing, and making of paper pulp.

Abstract: A method of depressing copper sulfides and iron sulfides in a molybdenite flotation recovery process that uses alkaline or alkaline earth polysulfides. The method of enriching molybdenite content from a slurry having molybdenite and at least one of iron sulfides and copper sulfides can include the steps of adding an effective amount of a depressing reagent selected from one or more alkaline polysulfides, alkaline earth polysulfides, or a mixture thereof, to the slurry, wherein the pH of the slurry is greater than about 8.0; and passing a gas through the slurry to separate material by selective flotation, and recovering the molybdenite from a froth.

Abstract: The invention relates to a process for preparing potassium thiosulfate, potassium sulfite or potassium bisulfite comprising the following steps: Step (1a): providing a potassium hydroxide or potassium carbonate solution for neutralizing acid forming components such as dissolving SO2 or H2S; Step (1b): providing an SO2 contacting solution, containing at least some potassium sulfite or potassium bisulfite or potassium thiosulfate; Step (2): providing SO2 gas; Step (3): reacting these to absorb the SO2 gas and to form an intermediate reaction mixture comprising potassium sulfite, or potassium bisulfite or a mixture thereof, and optionally recovering the potassium sulfite, or potassium bisulfite or a mixture thereof, and/or optionally using steps 4 and 5; Step (4): adding sulfur or sulfide containing compound containing sulfur having the oxidation state of 0, ?2 or of between 0 and ?2 to the reaction mixture and optionally potassium hydroxide or potassium carbonate, and reacting the mixture under suitable cond

Abstract: The invention relates to a process for preparing potassium thiosulfate, potassium sulfite or potassium bisulfite comprising the following steps: Step (1a): providing a potassium hydroxide or potassium carbonate solution for neutralizing acid forming components such as dissolving SO2 or H2S; Step (1b): providing an SO2 contacting solution, containing at least some potassium sulfite or potassium bisulfite or potassium thiosulfate; Step (2): providing SO2 gas; Step (3): reacting these to absorb the SO2 gas and to form an intermediate reaction mixture comprising potassium sulfite, or potassium bisulfite or a mixture thereof, and optionally recovering the potassium sulfite, or potassium bisulfite or a mixture thereof, and/or optionally using steps 4 and 5; Step (4): adding sulfur or sulfide containing compound containing sulfur having the oxidation state of 0, ?2 or of between 0 and ?2 to the reaction mixture and optionally potassium hydroxide or potassium carbonate, and reacting the mixture under suitable conditi

Abstract: The invention relates to a process for preparing potassium thiosulfate, potassium sulfite or potassium bisulfite comprising the following steps: Step (1a): providing a potassium hydroxide or potassium carbonate solution for neutralizing acid forming components such as dissolving SO2 or H2S; Step (1b): providing an SO2 contacting solution, containing at least some potassium sulfite or potassium bisulfite or potassium thiosulfate; Step (2): providing SO2 gas; Step (3): reacting these to absorb the SO2 gas and to form an intermediate reaction mixture comprising potassium sulfite, or potassium bisulfite or a mixture thereof, and optionally recovering the potassium sulfite, or potassium bisulfite or a mixture thereof, and/or optionally using steps 4 and 5; Step (4): adding sulfur or sulfide containing compound containing sulfur having the oxidation state of 0, ?2 or of between 0 and ?2 to the reaction mixture and optionally potassium hydroxide or potassium carbonate, and reacting the mixture under suitable cond

Abstract: An efficient process for preparation of potassium thiosulfate (K2S2O3) is described. Potassium hydroxide (KOH) and elemental sulfur (S) are converted to potassium polysulfide, which is subsequently oxidized. The process allows using specifically designed process conditions such as mole ratios of potassium hydroxide to sulfur, and temperature, to obtain an optimized formulation of desired polysulfide, and a specifically designed set of conditions such as temperature, pressure, rate and duration of the oxidant during the oxidation conditions, to obtain a relatively high concentration of soluble potassium thiosulfate product with high purity, with relatively low amounts of byproducts. The manufacturing process can either be a batch process or a continuous process utilizing Continuous Stirred Tank Reactors (CSTR). The CSTR process is dependent on several design parameters, including pressure, and temperature optimization to avoid product instability.

Abstract: The invention relates to a process for preparing potassium thiosulfate, potassium sulfite or potassium bisulfite comprising the following steps: Step (1a): providing a potassium hydroxide or potassium carbonate solution for neutralizing acid forming components such as dissolving SO2 or H2S; Step (1b): providing an SO2 contacting solution, containing at least some potassium sulfite or potassium bisulfite or potassium thiosulfate; Step (2): providing SO2 gas; Step (3): reacting these to absorb the SO2 gas and to form an intermediate reaction mixture comprising potassium sulfite, or potassium bisulfite or a mixture thereof, and optionally recovering the potassium sulfite, or potassium bisulfite or a mixture thereof, and/or optionally using steps 4 and 5; Step (4): adding sulfur or sulfide containing compound containing sulfur having the oxidation state of 0, ?2 or of between 0 and ?2 to the reaction mixture and optionally potassium hydroxide or potassium carbonate, and reacting the mixture under suitable cond

Abstract: An efficient process for preparation of potassium thiosulfate (K2S2O3) is described. Potassium hydroxide (KOH) and elemental sulfur (S) are converted to potassium polysulfide, which is subsequently oxidized. The process allows using specifically designed process conditions such as mole ratios of potassium hydroxide to sulfur, and temperature, to obtain an optimized formulation of desired polysulfide, and a specifically designed set of conditions such as temperature, pressure, rate and duration of the oxidant during the oxidation conditions, to obtain a relatively high concentration of soluble potassium thiosulfate product with high purity, with relatively low amounts of byproducts. The manufacturing process can either be a batch process or a continuous process utilizing Continuous Stirred Tank Reactors (CSTR). The CSTR process is dependent on several design parameters, including pressure, and temperature optimization to avoid product instability.

Abstract: A method of depressing copper sulfides and iron sulfides in a molybdenite floatation recovery process uses alkaline or alkaline earth polysulfides at high concentrate pH. The method of enriching molybdenite content from a slurry having molybdenite and at least one of iron sulfides and copper sulfides can include the steps of adding an effective amount of a depressing reagent selected from one or more alkaline poly sulfides, alkaline earth polysulfides, or a mixture thereof, to the slurry, wherein the pH of the slurry is greater than about 8.0; and passing a gas through the slurry to separate material by selective flotation, recovering the molybdonite from a froth.

Abstract: An efficient process for the continuous preparation of calcium thiosulfate (CaS2O3) from lime sulfur, through oxidation is described. The process involves oxidizing calcium polysulfide intermediate in a series of reactors to produce calcium thiosulfate as a clear liquid in high concentration with minimal byproducts. The process results in the complete destruction of polythionates, permitting the calcium thiosulfate produced to be useful in certain leaching processes for precious metals. The invention further makes it possible to recycle the process water from the leaching process for use as a raw material reactant in the process for calcium thiosulfate production.

Abstract: An efficient process for the continuous preparation of calcium thiosulfate (CaS2O3) from lime sulfur, through oxidation is described. The process involves oxidizing calcium polysulfide intermediate in a series of reactors to produce calcium thiosulfate as a clear liquid in high concentration with minimal byproducts. The process results in the complete destruction of polythionates, permitting the calcium thiosulfate produced to be useful in certain leaching processes for precious metals. The invention further makes it possible to recycle the process water from the leaching process for use as a raw material reactant in the process for calcium thiosulfate production.