Provided herein are methods and systems to form calcium carbonate comprising vaterite, comprising dissolving lime in an aqueous base solution under one or more precipitation conditions to produce a precipitation material comprising calcium carbonate and a supernatant solution, wherein the calcium carbonate comprises vaterite.

Provided is a method for recovering lithium, for recovering lithium from a lithium ion secondary battery, the method including: a thermal treatment step of thermally treating a lithium ion secondary battery having a residual voltage higher than or equal to 80% of a rated voltage, to obtain a thermally treated product; a pulverizing step of pulverizing the thermally treated product, to obtain a pulverized product; and a lithium recovering step of recovering lithium from the pulverized product.

A method for recovering valuable substance, for recovering it from lithium ion secondary battery includes: thermal treatment step of thermally treating lithium ion secondary battery to obtain thermally treated product; pulverizing/classifying step of classifying pulverized product obtained by pulverizing thermally treated product, to obtain coarse and fine-grained products both containing valuable substance; water leaching step of immersing fine-grained product in water, to obtain water-leached slurry; wet magnetic sorting step of subjecting water-leached slurry to wet magnetic sorting, to sort water-leached slurry into magnetically attractable materials and non-magnetically attractable material slurry; and acid leaching step of adding acidic solution to either or both of non-magnetically attractable material slurry recovered by wet magnetic sorting and non-magnetically attractable materials obtained by solid-liquid separation of non-magnetically attractable material slurry to leach non-magnetically attractable materials at pH lower than 4, followed by solid-liquid separation to obtain acid leaching liquid and acid leaching residue.

Disclosed is a method for fast and cost-efficient preparation of ikaite crystals. The method comprises contacting an alkaline aqueous solution, which comprises carbonate and bicarbonate ions, with a water solution, which comprises Ca.sup.2+, at a temperature not exceeding 15° C., wherein contact between the alkaline aqueous solution and the water solution takes place at a permeable or porous surface, through which either solution is fed to the other at a flow rate facilitating formation of ikaite crystals. Also disclosed is system for carrying out the ikaite preparation process. The process and system provides a cost efficient and effective means for capture and storage of carbon dioxide.

The invention is directed to kits, compositions, tools and methods comprising a cyclic industrial process to form biocement. In particular, the invention is directed to materials and methods for decomposing calcium carbonate into calcium oxide and carbon dioxide at an elevated temperature, reacting calcium oxide with ammonium chloride to form calcium chloride, water, and ammonia gas; and reacting ammonia gas and carbon dioxide at high pressure to form urea and water, which are then utilized to form biocement. This cyclic process can be achieved by combining industrial processes with the resulting product as biocement. The process may involve retention of calcium carbonate currently utilized in the manufacture of Portland Cement.

The invention is directed to kits, compositions, tools and methods comprising a cyclic industrial process to form biocement. In particular, the invention is directed to materials and methods for decomposing calcium carbonate into calcium oxide and carbon dioxide at an elevated temperature, reacting calcium oxide with ammonium chloride to form calcium chloride, water, and ammonia gas; and reacting ammonia gas and carbon dioxide at high pressure to form urea and water, which are then utilized to form biocement. This cyclic process can be achieved by combining industrial processes with the resulting product as biocement. The process may involve retention of calcium carbonate currently utilized in the manufacture of Portland Cement.

A process for converting natural calcium carbonate into precipitated calcium carbonate, involving treating the natural calcium carbonate with a sulfate to produce a gypsum and reacting the gypsum with at least one carbonate source to produce precipitated calcium carbonate. The crystalline polymorph, particle size, and various other characteristics of the precipitated calcium carbonate are controlled by varying conditions during the reacting. Since the natural calcium carbonate is not calcined, the process relates to a low energy method of producing precipitated calcium carbonate of controlled polymorph and particle size with limestone, marble, or chalk as the calcium source.

A process for converting natural calcium carbonate into precipitated calcium carbonate, involving treating the natural calcium carbonate with a sulfate to produce a gypsum and reacting the gypsum with at least one carbonate source to produce precipitated calcium carbonate. The crystalline polymorph, particle size, and various other characteristics of the precipitated calcium carbonate are controlled by varying conditions during the reacting. Since the natural calcium carbonate is not calcined, the process relates to a low energy method of producing precipitated calcium carbonate of controlled polymorph and particle size with limestone, marble, or chalk as the calcium source.

The present invention relates to a process for the preparation of precipitated calcium carbonate allowing for a more sustainable and cost-efficient use of milk of lime. The obtainable products show good optical properties as well as fine particle size distributions.

The present invention relates to a process for the preparation of precipitated calcium carbonate allowing for a more sustainable and cost-efficient use of milk of lime. The obtainable products show good optical properties as well as fine particle size distributions.