Provided are a calcium carbonate having a small particle diameter and easily dispersible in polymers and a production method therefor. A calcium carbonate has a magnesium content of 12000 to 120000 ppm, a BET specific surface area of 60 to 120 m.sup.2/g, and a crystallite size of (104) plane of 20 to 50 nm, and particles of the calcium carbonate are concatenated.

The present invention relates to the use of zinc treated precipitated calcium carbonate (PCC), which is obtained by slaking calcium oxide with water to obtain a calcium hydroxide slurry, carbonating the calcium hydroxide slurry, and adding a Zn.sup.2+ ion provider before and/or during the carbonation, in hygienic products, to the hygienic products comprising said zinc treated precipitated calcium carbonate as well as to a process for the preparation of such hygienic products.

Techniques for growing crystalline calcium carbonate solids such that the crystalline calcium carbonate solids include a volume of 0.0005 mm.sup.3 to 5 mm.sup.3, include a slaker to react quicklime (CaO) and a low carbonate content fluid to yield a slurry of primarily slaked lime (Ca(OH).sub.2); a fluidized-bed reactive crystallizer that encloses a solid bed mass and includes an input for a slurry of primarily slaked lime, an input for an alkaline solution and carbonate, and an output for crystalline calcium carbonate solids that include particles and an alkaline carbonate solution; a dewatering apparatus that includes an input coupled to the crystallizer and an output to discharge a plurality of separate streams that each include a portion of the crystalline calcium carbonate solids and alkaline carbonate solution; and a seed transfer apparatus to deliver seed material into the crystallizer to maintain a consistent mass of seed material.

The present invention relates to a method for the recovery of lithium products from an aqueous solution, the method comprising the steps of: (i.) contacting the solution with an alkaline material to precipitate a target amount of magnesium in the brine solution and separating the precipitated solids from an intermediate solution; (ii.) contacting the intermediate solution with a controlled amount of a hydroxide salt to precipitate magnesium in the intermediate solution; (iii.) contacting the intermediate solution with a controlled amount of sodium carbonate to precipitate impurities and separating the precipitated solids from a purified solution; and (iv.) recovering lithium products from the purified solution.

In this disclosure, a process of recycling acid, base and the salt reagents required in the Li recovery process is introduced. A membrane electrolysis cell which incorporates an oxygen depolarized cathode is implemented to generate the required chemicals onsite. The system can utilize a portion of the salar brine or other lithium-containing brine or solid waste to generate hydrochloric or sulfuric acid, sodium hydroxide and carbonate salts. Simultaneous generation of acid and base allows for taking advantage of both chemicals during the conventional Li recovery from brines and mineral rocks. The desalinated water can also be used for the washing steps on the recovery process or returned into the evaporation ponds. The method also can be used for the direct conversion of lithium salts to the high value LiOH product. The method does not produce any solid effluent which makes it easy-to-adopt for use in existing industrial Li recovery plants.

In this disclosure, a process of recycling acid, base and the salt reagents required in the Li recovery process is introduced. A membrane electrolysis cell which incorporates an oxygen depolarized cathode is implemented to generate the required chemicals onsite. The system can utilize a portion of the salar brine or other lithium-containing brine or solid waste to generate hydrochloric or sulfuric acid, sodium hydroxide and carbonate salts. Simultaneous generation of acid and base allows for taking advantage of both chemicals during the conventional Li recovery from brines and mineral rocks. The desalinated water can also be used for the washing steps on the recovery process or returned into the evaporation ponds. The method also can be used for the direct conversion of lithium salts to the high value LiOH product. The method does not produce any solid effluent which makes it easy-to-adopt for use in existing industrial Li recovery plants.

A method of treating a metal carbonate salt includes hydrolyzing a metal halide salt to form a hydrohalic acid and a hydroxide salt of the metal in the metal halide salt. The metal includes an alkaline earth metal or an alkali metal. The method includes reacting the hydrohalic acid with the metal carbonate salt, wherein the metal carbonate salt is a carbonate salt of the alkaline earth metal or alkali metal, to form CO.sub.2 and the metal halide salt. At least some of the metal halide salt formed from the reacting of the hydrohalic acid with the metal carbonate salt is recycled as at least some of the metal halide salt in the hydrolyzing of the metal halide salt to form the hydrohalic acid and the hydroxide salt.

Disclosed are a method and a system for recycling carbon dioxide. The method includes chlorinating a calcium-containing silicate and/or a magnesium-containing silicate to obtain a calcium chloride and/or magnesium chloride, mixing the calcium chloride and/or magnesium chloride with ammonia water and carbon dioxide and performing a carbonation reaction to recover the carbon dioxide and convert it into calcium carbonate and/or magnesium carbonate while generating an ammonium chloride solution, and recovering the ammonium chloride solution generated in the carbonation reaction. The ammonium chloride solution after being concentrated or hydrogen chloride generated from a decomposition reaction of the ammonium chloride solution is directly used to chlorinate the calcium-containing silicate and/or the magnesium-containing silicate. The ammonium chloride is used as a catalyst for the entire mineralization of the carbon dioxide, the final product is the calcium carbonate and/or the magnesium carbonate.

Provided herein is a method of preparing a ceramic material, the method including: providing a ceramic gel including a plurality of metal salts and compressing the ceramic gel thereby inducing stress-induced mineralization of the ceramic gel and formation of the ceramic material, wherein the ceramic gel exists in isolated form.

In this disclosure, a process of recycling acid, base and the salt reagents required in the Li recovery process is introduced. A membrane electrolysis cell which incorporates an oxygen depolarized cathode is implemented to generate the required chemicals onsite. The system can utilize a portion of the salar brine or other lithium-containing brine or solid waste to generate hydrochloric or sulfuric acid, sodium hydroxide and carbonate salts. Simultaneous generation of acid and base allows for taking advantage of both chemicals during the conventional Li recovery from brines and mineral rocks. The desalinated water can also be used for the washing steps on the recovery process or returned into the evaporation ponds. The method also can be used for the direct conversion of lithium salts to the high value LiOH product. The method does not produce any solid effluent which makes it easy-to-adopt for use in existing industrial Li recovery plants.