A method for destructing and valorizing an asbestos waste including the steps of: determining the asbestos mineralogical group contained in the waste, performing a treatment on the waste which includes of: an acid treatment when the waste comprises only a chrysotile, a base treatment when the waste comprises only an amphibole, the acid treatment followed by the base treatment when the asbestos waste includes a mixture of a chrysotile and an amphibole, and valorizing at least one of the products obtained on completion of the performing of the treatment. An embodiment also concerns a treatment of a chrysotile waste through an acid treatment followed by a thermal treatment.

A method for destructing and valorizing an asbestos waste including the steps of: determining the asbestos mineralogical group contained in the waste, performing a treatment on the waste which includes of: an acid treatment when the waste comprises only a chrysotile, a base treatment when the waste comprises only an amphibole, the acid treatment followed by the base treatment when the asbestos waste includes a mixture of a chrysotile and an amphibole, and valorizing at least one of the products obtained on completion of the performing of the treatment. An embodiment also concerns a treatment of a chrysotile waste through an acid treatment followed by a thermal treatment.

A process for the manufacture of inorganic fibres comprises: (a) selecting a composition and proportion of: (i) silica sand; (ii) lime comprising at least 0.10 wt % magnesia; and (iii) optional additives comprising a source of oxides or non-oxides of one or more of the lanthanides series of elements, or combinations thereof; (b) mixing the silica sand; lime; and optional additives to form a mixture; (c) melting the mixture in a furnace; and (d) shaping the molten mixture into inorganic fibres. The raw materials selection comprises composition selection and proportion selection of the raw materials to obtain an inorganic fibre composition comprising a range of from 61.0 wt % and 70.8 wt % silica; less than 2.0 wt % magnesia; less than 2.0% incidental impurities; and no more than 2.0 wt % of metal oxides and/or metal non-oxides derived from said optional additives; with calcia providing the balance up to 100 wt %; and wherein the inorganic fibre composition comprises no more than 0.80 wt % Al.sub.2O.sub.3 derived from the incidental impurities and/or the optional additives.

A process for the manufacture of inorganic fibres comprises: (a) selecting a composition and proportion of: (i) silica sand; (ii) lime comprising at least 0.10 wt % magnesia; and (iii) optional additives comprising a source of oxides or non-oxides of one or more of the lanthanides series of elements, or combinations thereof; (b) mixing the silica sand; lime; and optional additives to form a mixture; (c) melting the mixture in a furnace; and (d) shaping the molten mixture into inorganic fibres. The raw materials selection comprises composition selection and proportion selection of the raw materials to obtain an inorganic fibre composition comprising a range of from 61.0 wt % and 70.8 wt % silica; less than 2.0 wt % magnesia; less than 2.0% incidental impurities; and no more than 2.0 wt % of metal oxides and/or metal non-oxides derived from said optional additives; with calcia providing the balance up to 100 wt %; and wherein the inorganic fibre composition comprises no more than 0.80 wt % Al.sub.2O.sub.3 derived from the incidental impurities and/or the optional additives.

In some aspects, the present disclosure pertains to methods for the electrochemical production of calcium silicate compounds in an electrochemical cell that comprises (a) a Ca-based electrode that comprises calcium metal or an inorganic calcium material, (b) an SiO.sub.x-based electrode that comprises a SiO.sub.x material, where x ranges from 1 to 2, and (c) a liquid electrolyte disposed between the Ca-based electrode and the SiO.sub.x-based electrode. In these methods, the electrochemical cell is operated under conditions such that calcium cations are produced at the Ca-based electrode and one or more calcium silicate (Ca—Si-oxide) compounds are produced at the SiO.sub.x-based electrode. In other aspects, the present disclosure pertains to systems for the electrochemical production of calcium silicate compounds.

A negative electrode active material, a negative electrode including the same, a secondary battery including the same and a method for preparing a negative electrode active material.

A negative electrode active material, a negative electrode including the same, a secondary battery including the same and a method for preparing a negative electrode active material.

A method for deep desiliconization of coal ash and recovery of silicon resources includes: ball-milling and drying decarburized coal ash; adding calcium oxide into a salt to obtain a mixture, and heating the mixture to a molten state under an inert atmosphere to obtain a molten salt, a molar ratio of the calcium oxide to the salt ranging from 0.5% to 18%; placing the ball-milled and dried coal ash into the molten salt, performing reaction under an atmospheric pressure, separating a reaction product from the molten salt, cooling the separated reaction product under an inert atmosphere, washing the cooled reaction product and drying the washed reaction product to obtain desiliconized coal ash; and cooling the molten salt under an inert atmosphere, washing the cooled salt and filtering the washed salt to recover calcium silicate and a filtrate.

A method for deep desiliconization of coal ash and recovery of silicon resources includes: ball-milling and drying decarburized coal ash; adding calcium oxide into a salt to obtain a mixture, and heating the mixture to a molten state under an inert atmosphere to obtain a molten salt, a molar ratio of the calcium oxide to the salt ranging from 0.5% to 18%; placing the ball-milled and dried coal ash into the molten salt, performing reaction under an atmospheric pressure, separating a reaction product from the molten salt, cooling the separated reaction product under an inert atmosphere, washing the cooled reaction product and drying the washed reaction product to obtain desiliconized coal ash; and cooling the molten salt under an inert atmosphere, washing the cooled salt and filtering the washed salt to recover calcium silicate and a filtrate.

A negative electrode active material including a core containing SiO.sub.x (0≤x<2) and a lithium-containing compound, and a shell disposed on the core and containing SiO.sub.x (0≤x<2) and magnesium silicate.