New dual temperature electrochemical methods and systems for the production of sodium metal from sodium polysulfides have been discovered. The technology provides high conductivity for sodium ions and extended service life for the electrochemical cell.

A method of improving metal leach kinetics and recovery during atmospheric or substantially atmospheric leaching of a metal sulfide is disclosed. In some embodiments, the method may comprise the step of processing a metal sulfide concentrate in a reductive activation circuit 220 that operates at a first redox potential, to produce a reductively-activated metal sulfide concentrate. The method may further comprise the step of subsequently processing the activated metal sulfide concentrate in an oxidative leach circuit 240 to extract metal values. In some disclosed embodiments, reductive activation steps and/or oxidative dissolution steps may employ mechano-chemical and/or physico-chemical processing of particles or agglomerates thereof. Reductive activation may be made prior to heap leaching or bio-leaching operations to improve metal extraction. Systems for practicing the aforementioned methods are also disclosed.

A vulcanizing composition useful for the vulcanization of vulcanizable formulations is disclosed. The vulcanizing composition includes a vulcanizing agent which in turn includes a cyclododecasulfur compound. A cyclododecasulfur compound characterized by a DSC melt point onset of between 155° C. and 167° C. when measured at a DSC heat rate of 20° C./minute is also disclosed.

A vulcanizing composition useful for the vulcanization of vulcanizable formulations is disclosed. The vulcanizing composition includes a vulcanizing agent which in turn includes a cyclododecasulfur compound. A cyclododecasulfur compound characterized by a DSC melt point onset of between 155° C. and 167° C. when measured at a DSC heat rate of 20° C./minute is also disclosed.

Processes for forming a vulcanizable elastomeric formulation are disclosed. The processes include the steps of mixing an elastomer with a vulcanizing agent to form a vulcanizable elastomeric formulation that includes the vulcanizing agent dispersed in the elastomeric compound, wherein the vulcanizing agent includes a cyclododecasulfur compound. A process for forming a vulcanized elastomeric article is also described.

Methods for producing cyclododecasulfur are disclosed that include the steps of: reacting a metallasulfur derivative with a molecular halogen to produce cyclododecasulfur and a metallahalide derivative; and reacting the metallahalide derivative with a sulfide or polysulfide to produce the metallasulfur derivative and a halide.

Methods for producing cyclododecasulfur are disclosed that include the steps of: reacting a metallasulfur derivative with a molecular halogen to produce cyclododecasulfur and a metallahalide derivative; and reacting the metallahalide derivative with a sulfide or polysulfide to produce the metallasulfur derivative and a halide.

Methods for producing cyclododecasulfur are disclosed, that include the steps of: oxidizing a bromide in aqueous solution to produce a mixture of molecular bromine, tribromide, and bromide; reducing water to produce hydrogen and a hydroxide; and reacting a metallasulfur derivative with the molecular bromine, to produce cyclododecasulfur and a metallabromide derivative.

Methods for producing cyclododecasulfur are disclosed, that include the steps of: oxidizing a bromide in aqueous solution to produce a mixture of molecular bromine, tribromide, and bromide; reducing water to produce hydrogen and a hydroxide; and reacting a metallasulfur derivative with the molecular bromine, to produce cyclododecasulfur and a metallabromide derivative.

Methods for producing cyclododecasulfur are disclosed that include the steps of: reacting a bromide with molecular chlorine to obtain molecular bromine and a chloride; oxidizing the chloride in aqueous solution with removal of electrons to obtain molecular chlorine; reducing water with electrons to obtain hydrogen and a hydroxide; and reacting a metallasulfur derivative with the molecular bromine, to produce cyclododecasulfur and a metallabromide derivative.