Disclosed herein are systems and methods from processing flue gas desulfurization (FGD) gypsum feedstock and ash feedstocks, either separately or together. FGD gypsum conversion comprises reacting FGD gypsum (calcium sulfate) feedstock or phosphogypsum, in either batch or continuous mode, with ammonium carbonate reagent to produce commercial products comprising ammonium sulfate and calcium carbonate. A process to separate the impurities and convert the calcium carbonate to a pure precipitated calcium carbonate is disclosed. These impurities include a concentrate of valuable Rare Earth Elements, and radioactive thorium and uranium. A process to convert calcium sulfite to calcium sulfate using oxygen and a catalyst is also disclosed. Ash conversion comprises a leach process followed by a sequential precipitation process to selectively precipitate products at predetermined pHs resulting in metal hydroxides which may be converted to oxides or carbonates. The processes may be controlled by use of one or more processors.

The present invention relates to a method for transesterification of carboxylic acid esters by heterogeneous catalysis using a catalyst that is obtainable by calcination of surface-reacted calcium carbonate. The invention further relates to the use of said method in the production of fuel or fuel components, such as biodiesel. Further aspects of the present invention relate to the transesterified ester obtainable by the inventive method and to its use as fuel or as fuel component. Still another aspect of the present invention relates to a corresponding transesterification catalyst and to its use in transesterification reactions.

Inorganic particulate compositions containing inorganic particles associated with a copolymer of a hydrophilic monomer and a hydrophobic monomer associated with the inorganic particles are provided. The particulate composition satisfies at least one of the following properties: a BET surface area of the inorganic particles is greater than 8 m.sup.2/g, a Hegman value of the inorganic particles is 75 microns or less, and a rate of water loss from the composition upon drying from a moisture level greater than 2% wt % is at least 30% greater than a composition having a corresponding content of a polyacrylate polymer associated with the particles. A method to prepare the composition and formulations for inks, paints, coatings and filled polymeric articles containing the inorganic particulate composition are also provided.

The present application relates to aqueous slurries comprising precipitated calcium carbonates having a bimodal particle size distribution with a first maximum in particle size distribution and a second maximum in particle size distribution, as well as methods for making them and their uses.

A method for releasing impurities from a calcium-based mineral is described. The method comprises reacting a calcium-based mineral containing impurities with an aqueous solution of one or more ionic salts at a temperature of approximately 85° C. or above, wherein at least one of the calcium-based mineral and the one or more ionic salts comprises sulphate and at least one of the calcium-based mineral and the one or more ionic salts comprises ammonium, and wherein the concentration of the solution is approximately 25% or higher mass fraction, such that double salt crystals are formed and impurities are released. The method further comprises separating the double salt crystals from the impurities. Various products of the process are also described.

Methods for preparing and compositions including untreated and surface-treated alkaline earth metal carbonate particulates are described. For example, a method for processing alkaline earth metal carbonate may include introducing alkaline earth metal carbonate into a stirred media mill, and dry grinding the alkaline earth metal carbonate in the stirred media mill to produce an untreated alkaline earth metal carbonate particulate having certain characteristics. In some examples, the method may include introducing carboxylic acid and/or carboxylic acid salt into the stirred media mill, and dry grinding the alkaline earth metal carbonate and the carboxylic acid and/or carboxylic acid salt in an integrated dry grinding and surface-treating process in the stirred media mill to produce a surface-treated alkaline earth metal carbonate particulate. In some examples, heating may be added during the dry grinding process.

Divalent ions are extracted from solids by leaching to form a divalent ion-containing solution. The divalent ion-containing solution is subjected to concentration to form a concentrated divalent ion-containing solution. Precipitation of a divalent ion hydroxide salt is induced from the concentrated divalent ion-containing solution. In other cases, the concentrated divalent ion-containing solution is exposed to carbon dioxide to induce precipitation of a divalent ion carbonate salt.

The disclosure relates to core-shell nanoparticle, the nanoparticle comprising a core being one or more selected from vaterite, proto-vaterite, and amorphous calcium carbonate as determined by X-Ray diffraction, remarkable in that the nanoparticle further comprises a shell of polyphenol, wherein said polyphenol is selected to be insoluble in water, to show a pH ranging from 5 to 9 when measured in a solution of one or more polar solvents and water at a concentration of 10 wt. % based on the total weight of said solution and wherein said polyphenol is at least partially soluble in said one or more polar solvents. A method for forming such nanoparticle as well as their use and the use of polyphenol as shell of shell-core nanoparticle is also described.

Inorganic particulate compositions containing inorganic particles associated with a copolymer of a hydrophilic monomer and a hydrophobic monomer associated with the inorganic particles are provided. The particulate composition satisfies at least one of the following properties: a BET surface area of the inorganic particles is greater than 8 m.sup.2/g, a Hegman value of the inorganic particles is 75 microns or less, and a rate of water loss from the composition upon drying from a moisture level greater than 2% wt % is at least 30% greater than a composition having a corresponding content of a polyacrylate polymer associated with the particles. A method to prepare the composition and formulations for inks, paints, coatings and filled polymeric articles containing the inorganic particulate composition are also provided.

The present invention relates to at least one surface-reacted calcium carbonate-comprising mineral material and/or a surface-reacted precipitated calcium carbonate that is/are coated with at least one anionic polymer to obtain a surface-coated calcium carbonate-comprising material as well as to a process for the preparation of the surface-coated calcium carbonate-comprising material. Furthermore, the present invention relates to a process for the purification of water and/or dewatering of sludges and/or suspended sediments and to the use of a surface-coated calcium carbonate-comprising material for water purification and/or dewatering of sludges and/or suspended sediments.