329 results about "Calcium Sulfate Dihydrate" patented technology

Polymerization of siloxane is improved using a gypsum-based slurry that includes stucco, Class C fly ash, magnesium oxide and an emulsion of siloxane and water. This slurry is used in a method of making water-resistant gypsum articles that includes making an emulsion of siloxane and water, then combining the slurry with a dry mixture of stucco, magnesium oxide and Class C fly ash. The slurry is then shaped as desired and the stucco is allowed to set and the siloxane polymerizes. The resulting product is useful for making a water-resistant gypsum panel having a core that includes interwoven matrices of calcium sulfate dihydrate crystals and a silicone resin, where the interwoven matrices have dispersed throughout them a catalyst comprising magnesium oxide and components from a Class C fly ash.

An improved, fire-resistant, set gypsum composition contains set calcium sulfate dihydrate as the major ingredient and a reinforcing ingredient of resilient, flexible, boron-free glass fibers. Continuous filament forming glass compositions with a softening point preferably greater than about 1580° F. (about 860° C.) and more preferably greater than about 1681° F. (about 916° C.) may be used. The fibers typically are distributed as their separate constituent individual glass filaments uniformly throughout the set calcium sulfate dihydrate.

A mold-resistant gypsum panel includes a core of an interlocking matrix of calcium sulfate dihydrate crystals, a facing material on at least one side of the panel and a salt of pyrithione dispersed through both the core and the facing materials. A method of making a mold-resistant gypsum product is also provided. A slurry of calcined gypsum, water and a water-soluble pyrithione salt is formed, then deposited on a sheet of facing material. The slurry on the facing material is shaped into a panel and maintained under conditions sufficient for the calcined gypsum to react with the water to form a core comprising an interlocking matrix of set gypsum crystals. Heating of the panel causes evaporation of the water that did not react with the calcined gypsum.

The invention relates to a phase-change energy-storage material which comprises the following components in percentage by mass: 75%-99% of an energy storage main body material, 0.1%-10% of a thickening agent, 0.2%-15% of a nucleating agent and 0.01%-8% of a reinforcing material, wherein the energy storage main body material comprises crystal water and salt; the thickening agent comprises one or more of an inorganic thickening agent, fibers, polyacrylates, polyurethanes and a natural polymer thickening agent; the nucleating agent comprises one or more of sodium pyrophosphate, sodium phosphate decahydrate, calcium sulfate dihydrate, potassium sulfate, potassium borate, barium hydroxide octahydrate, sodium phosphate dibasic dodecahydrate and sodium sulfate; the reinforcing material comprises one or more of metal and metal oxide powder, carbon materials, nanoparticles and foam materials. By selecting proper materials and ratio, the supercooling degree and the phase separation phenomenon are reduced and good circulating stability is achieved; especially the reinforcing material is added into a system to form a heat-conducting network so as to improve the heat conductivity of the material by more than two times.

The invention provides a method for preparing alpha semi-hydrated gypsum by utilizing desulfurized gypsum, comprising the technological steps of purification, crystal transforming reaction, oriented crystallization, washing and separation, and drying and pulverization. The method concretely comprises the following steps of: enhancing the taste of calcium sulfate dlhy in the desulfurized gypsum to be greater than 95% through a purification treatment; dissolving and recrystallizing the desulfurized gypsum at 70 to 98 DEG C under the normal pressure through adding prepared habit modifiers, transforming into the alpha semi-hydrated gypsum and then carrying out oriented crystallization on the alpha semi-hydrated gypsum to form a short column-shaped alpha semi-hydrated gypsum crystal under the function of an oriented crystal type stabilizer, wherein the length-diameter ratio of the short column-shaped alpha semi-hydrated gypsum crystal is less than 1:3, the 2h breaking strength is greater than 6.5 MPa, the compression strength is greater than 23 MPa, the dry breaking strength is greater than 25 MPa, and the dry compression strength is greater than 53 MPa. The method can be widely used in the fields of ceramics, automobiles, precise casting, heterogenic casting and the like.

A process is disclosed for making a blend of alpha- and beta-stucco including a slurry calcination step to produce alpha calcium sulfate hemihydrate followed by a fluidized bed calcination step to produce beta calcium sulfate hemihydrate. The process starts with 50-75% gypsum-containing solids slurry, and then steam calcines the slurry in a first reactor to form partially calcined gypsum slurry which contains calcium sulfate dihydrate and alpha calcium sulfate hemihydrate. The partially calcined slurry is then dewatered. Then the filter cake is fed into a kettle to complete the calcination process by converting the calcium sulfate dihydrate of the filter cake material into beta calcium sulfate hemihydrate.

The invention provides a composition useful as a joint compound comprising water, a filler comprising one or more of calcium carbonate, calcium sulfate dihydrate or calcium sulfate hemihydrate, a binder and/or a biocide, wherein the composition after curing is formaldehyde-free.

The invention discloses a method for preparing calcium sulfate crystal whiskers from desulfurized gypsum under normal pressure. The method comprises the following steps: 1) pickling; 2) dissolving; 3) rotating crystal; and 4) crystallizing, after crystallizing, carrying out solid-liquid separation, washing filter cake with water, and drying to obtain calcium sulfate crystal whiskers. The method disclosed by the invention has the advantages that: the preparation process is simple and is easy to achieve, and the production efficiency is high; higher-purity and higher-whiteness calcium sulfate crystal whiskers are prepared by adopting a normal-pressure recrystallization method, controlling related process conditions and utilizing the characteristic that the dissolubility of main component calcium sulfate dihydrate of desulfurized gypsum in specific solution changes obviously along with the temperature; obtained calcium sulfate crystal whisker product has regular morphology, low agglomeration and good dispersity; and in addition, inorganic acid solution used for recrystallization can be recycled, and inorganic acid solution is not consumed in the reaction process, thereby creating better economic benefit, environmental benefit and social benefit, reducing the burden of coal-fired power plant and increasing enterprise benefits.

A method is provided which uses an improved emulsion to imparting water-resistance to gypsum products. In one embodiment, gypsum products comprise calcium sulfate dihydrate and an emulsion which comprises a saponified wax, a nonsaponifiable wax, an alkyl phenol, a surfactant/dispersant salt of polynaphthalenesulfonic acid, and carboxymethylcellulose. Optionally, the emulsions may contain a preservative, e.g., a biocide (mildewcide, fungicide, etc.). These gypsum products resist the uptake of water and therefore resist biological infestation without addition of a preservative.

A method of making a rapid setting lightweight homogeneous foamed fly ash based cementitious aggregate composition with improved compressive strength for products such as panels is disclosed. The method mixes fly ash, alkali metal salt of citric acid, foaming agent for entraining air, optional foam stabilizing agent, a calcium sulfate such as stucco or gypsum, and water. Compositions are also disclosed which include mixtures of fly ash, particularly Class C fly ash alone or in mixtures with Class F fly ash, alkali metal salts of citric acid, foaming agents, a calcium sulfate such as calcium sulfate dihydrate or hemihydrate and an optional portland cement.

The invention discloses a comprehensive utilization method of titanium white waste acid wastewater, which belongs to the field of metallurgy. The method of the invention aims to solve the technical problem in the prior art that the titanium white waste acid wastewater cannot be fully utilized at low cost. The method for comprehensive utilization of titanium white waste acid waste water comprises the following steps: a. adding limestone to the hydrochloric acid solution, fully reacting to obtain a calcium chloride solution; b. adding titanium white waste acid or waste water to the calcium chloride solution, filtering after fully reacting Obtain calcium sulfate dihydrate and filtrate, described calcium sulfate dihydrate obtains product gypsum through drying process; c, the filtrate obtained in step b is used as the raw material for preparing calcium chloride solution and reacts with limestone, after repeating steps a and b more than once , adding sodium hydroxide solution to the filtrate obtained in step b, and filtering to obtain a sodium chloride solution and a precipitate rich in iron, titanium, vanadium, scandium and gallium after sufficient reaction. The method of the invention has low cost, can well solve the problem of environmental pollution caused by titanium dioxide waste acid and waste water, and has good promotion prospects.

The invention discloses preparation methods of medical alpha-calcium sulfate hemihydrate powder and a calcium sulfate artificial bone material, belonging to the field of medical biomaterials. According to the invention, alpha-calcium sulfate hemihydrate is prepared by adding anhydrous alcohol to a reactant liquid containing calcium chloride, a crystal modifier and distilled water, wherein the volume ratio of the anhydrous alcohol to the distilled water is 0.01-2, so that the crystal water of calcium sulfate dihydrate is partially removed in the reactant liquid. Due to the modification effect of the anhydrous alcohol, the grain morphology and size of the alpha-calcium sulfate hemihydrate powder are effectively improved, and isometric or approximately isometric alpha-calcium sulfate hemihydrate powder with high purity and uniform crystal structure and particle size distribution is obtained. A medical calcium sulfate artificial bone material prepared by mixing and curing the alpha-calcium sulfate hemihydrate powder with a curing liquid can effectively improve the compressive strength, prolong the degradation time and improve the biological performance, so that the medical calcium sulfate artificial bone material has high performance and good application prospects in the technical fields of medical bone transplantation and bone repair.

A freeze-thaw durable, dimensionally stable, geopolymer composition including: cementitious reactive powder including thermally activated aluminosilicate mineral, aluminate cement preferably selected from at least one of calcium sulfoaluminate cement and calcium aluminate cement, and calcium sulfate selected from at least one of calcium sulfate dihydrate, calcium sulfate hemihydrate, and anhydrous calcium sulfate; alkali metal chemical activator; and a freeze-thaw durability component selected from at least one of air-entraining agent, defoaming agent, and surface active organic polymer; wherein the composition has an air content of about 4% to 20% by volume, more preferably about 4% to 12% by volume, and most preferably about 4% to 8% by volume. The compositions are made from a slurry wherein the water/cementitious reactive powder weight ratio is 0.14 to 0.45:1, preferably 0.16 to 0.35:1, and more preferably 0.18 to 0.25:1. Methods for making the compositions are also disclosed.

Disclosed is an improved alpha-type calcium sulfate hemihydrate. Methods of producing an improved powdered calcium sulfate hemihydrate (CaSO₄.½H₂O) [alpha-type] compound are disclosed, at least one method including forming calcium sulfate dihydrate (CaSO₄O.2H₂O) into a briquette, calcining the briquette to transform the calcium sulfate dihydrate to calcium sulfate hemihydrate [alpha-type], drying the calcium sulfate hemihydrate [alpha-type] briquette, and optionally grinding the briquette. Also disclosed are methods of producing an improved gypsum plaster including producing the disclosed powdered calcium sulfate hemihydrate [alpha-type] and mixing the powdered calcium sulfate hemihydrate [alpha-type] with water.

The invention relates to a method for preparing calcium sulfate whiskers and magnesium hydroxide by decomposing phosphate tailings through hydrochloric acid. The method comprises the following steps: adding phosphate tailings and hydrochloric acid into a decomposing tank to adequately react in the decomposing tank, and carrying out solid-liquid separation I on reacted slurry, so as to separate first mother solution and solid waste residues, wherein the solid waste residues are acid-insoluble substances; adding sulfuric acid into the first mother solution to react for crystallization, so as to generate the calcium sulfate whiskers; carrying out solid-liquid separation on crystallized slurry, so as to separate calcium sulfate dihydrate whiskers, wherein the mother solution is a mixed mother solution containing magnesium chloride and hydrochloric acid; after magnesium chloride in the mixed mother solution reaches a certain concentration, starting to take out a part of mixed mother solution, carrying out flash evaporation to evaporate HCl in the mother solution so as to obtain the mother solution mainly containing magnesium chloride, and returning the rest part of the mixed mother solution to the decomposing tank; introducing ammonia gas into the magnesium chloride mother solution, and carrying out solid-liquid separation, so as to obtain a relatively pure magnesium chloride mother solution and magnesium ammonium chloride solids containing a small amount of impurities; and absorbing HCl gas in the front stage by a magnesium ammonium chloride solution to enable the pH value of the magnesium ammonium chloride solution to be close to neutrality, and carrying out concentration and crystallization, so as to obtain magnesium ammonium chloride crystals. The method has the advantage that magnesium hydroxide and the calcium sulfate whiskers which have relatively high quality can be produced from industrial waste and the cheap raw materials.

A composition for a slurry for manufacture of a building panel includes one or more fillers, one or more binders and water. One or more fillers is an expanded perlite at least partially covered with a film-forming, thermoplastic polymer coating Some embodiments use calcined or uncalcined gypsum as a binder or filler. One embodiment is a building panel that includes a solid matrix of calcium sulfate dihydrate crystals bound to expanded perlite.

A method of making the panel includes acquiring expanded perlite and coating it with film-forming, thermoplastic polymer coating. After the expanded perlite is prepared, it is combined with water other optional fillers and one or more binders to form a slurry. The slurry is shaped into a panel and allowed to dry.