The present invention relates to a process for the preparation of an aqueous suspension comprising at least one calcium carbonate-containing material. The invention further relates to calcium carbonate-containing material having a ratio of particles having an average particle size d.sub.80 value to particles having an average particle size d.sub.20 value [d.sub.80/d.sub.20] of ?2.50 and the use of the calcium carbonate-containing material in paper and board applications, in cosmetics, in caulks and sealants, in paints and coatings, or in plastics applications.

Provided are a surface-treated calcium carbonate filler useful in a curable resin, for imparting performance having excellent heat resistance, color fastness, strength and elongation, and a curable resin containing the filler. A surface-treated calcium carbonate filler for a curable resin composition, in which calcium carbonate synthesized using compact limestone is treated by a surface treatment agent, the surface-treated calcium carbonate filler satisfying the following formulae (1) to (4):
0Mg2000,(1)
0Fe200,(2)
70SFa100, and(3)
0Ufa30,(4)
Mg: a proportion [ppm] of magnesium contained in surface-treated calcium carbonate, Fe: a proportion [ppm] of iron contained in surface-treated calcium carbonate, SFa: a proportion [wt %] of saturated fatty acid in the surface treatment agent comprising a water-soluble monovalent salt of a fatty acid, and UFa: a proportion [wt %] of unsaturated fatty acid in the surface treatment agent comprising a water-soluble monovalent salt of a fatty acid.

Process for the manufacture of a material on the basis of calcium- and/or magnesium carbonate having a reduced decrepitation tendency, wherein a material on the basis of calcium- and/or magnesium carbonate is treated with at least one additive selected among alkali metal compounds and/or acids and/or alkaline earth metal compounds in an amount of 0.05 to 5 wt. % based on the amount of the material on the basis of calcium- and/or magnesium carbonate. Also claimed are the material obtainable by the process and showing reduced decrepitation tendency and the use of such material in the manufacture of glass.

The present invention relates to a process for the manufacturing of a calcium carbonate-comprising material, to a calcium carbonate-comprising material obtained by the process as well as the use of the calcium carbonate-comprising material for paper filler and paper coating applications, in plastics applications, in paints, in adhesives, in sealings, in concrete, in agriculture applications, in food applications, in cosmetic applications or in pharmaceutical applications.

Disclosed is a method for preparing an organic environment-friendly snow-melting agent by using salt mud from a two-alkali method, relates to the field of environmental protection and resource utilization of solid wastes. The method includes the following steps: first, stirring and reacting an organic acid and the salt mud from a two-alkali method at room temperature to obtain a slurry; filtering the slurry to obtain a filtrate; the filtrate is then concentrated and dried by centrifugal spray drying to obtain a solid powder; granulating the solid powder. The method not only realizes the recycling of salt mud solid waste, but also greatly reduces the production cost of organic environment-friendly snow melting agent by turning waste into wealth, moreover, due to the existence of trace ions, the ability of melting snow and ice has obvious synergistic effect.

A method for separating membrane from an avian eggshell comprising the steps of providing pieces of egg shell having attached membrane, contacting the pieces of egg shell having attached membrane with a carbonic anhydrase enzyme or an acidic aqueous medium, applying physical force to the pieces of egg shell having attached membrane, and separating the pieces of egg shell from the detached membrane. A method of producing purified calcium carbonate comprising the steps of; providing impure calcium carbonate material, contacting the impure calcium carbonate material with an aqueous acid to produce carbon dioxide and an aqueous product mixture comprising a calcium salt, adding an aqueous base to the aqueous product mixture, adding a carbonate source to the aqueous product mixture to produce calcium carbonate and a salt by-product, and precipitating purified calcium carbonate.

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.

The present invention relates to a composition comprising a first component being an inorganic mineral or mineral-like material having a porous structure, and a second component being a hygroscopic compound; a process for preparing such a composition; a composite material comprising a such a composition; a product comprising such a composition and/or composite material as well as a use of such a composition and/or a composite material as a flame retardant or as a humidity adjusting agent.

Provided is a calcium carbonate that comprises crystals having a particular shape and structure and has a nano-order average particle size. Provided are a method for producing a calcium carbonate that comprises crystals having a particular shape and structure and has an average particle size in a particular range and a crystal growth method. The calcium carbonate has the calcite structure, has a BET specific surface area of 2 to 50 m.sup.2/g, has a number-based average particle size of 30 nm to 1.0 ?m as determined by electron microscopy, and partially comprises substantially ring-like particles.