391 results about "Calcium Sulfate Hemihydrate" patented technology

An improved water resistant gypsum board is made by adding an aqueous wax emulsion containing a cationic surfactant to an aqueous slurry containing calcium sulfate and host particles at a slurry temperature which maintains calcium sulfate hemihydrate crystals. The wax emulsion is stable at the temperature of slurry which maintains the calcium sulfate hemihydrate. The slurry is then dewatered and rehydrated to form a gypsum board and dried at a temperature to melt the wax.

An improved gypsum slurry that includes water, calcium sulfate hemihydrate, a polycarboxylate dispersant and a modifier. The modifier is chemically configured to improve the efficacy of the polycarboxylate dispersant. Preferred modifiers include cement, lime, slaked lime, soda ash, carbonates, silicates and phosphates.

The invention belongs to the technical field of rapid-molding materials, and discloses a rapid-molding powder material for three-dimensional printing as well as a preparation method and application thereof. The rapid-molding powder material is prepared by mixing and drying the following components by mass percent: 50% to 70% of molding powder A, 10% to 30% of molding powder B, 5% to 10% of water-soluble bonder powder, 1% to 10% of enhancer and 0.5% and 2% of aiding agent, wherein the molding powder A is of alpha-type calcium sulfate hemihydrate gypsum powder; the molding powder B is at least one powder of thermoplastic resin powder, wax powder or hot melt adhesive powder. The obtained rapid-molding powder material can be used for preparing three-dimensional printing prototypes, rapid-molding moulds, medical moulds and the like, and has the advantages of high strength and accuracy, small dimensional deviation, good water resistance and difficult powder bonding.

The invention provides a method for producing dehydrated calcium sulfate whisker, comprising: using copper, lead, zinc, aluminium, nickel, cobalt, stannum, non-ferrous metal secondary resource cycle utilizing, calcium nitrate solution produced in treating process of electroplating waste, calcium chloride solution, or mixed water solution of calcium nitrate and calcium chloride as raw material, using sulfuric acid as calcium ion precipitant, adding whisker shape regulating agent, controlling reaction condition, regenerating aqua fortis or hydrochloric acid lixiviant, and simultaneously producing ultralong and big length to diameter ratio calcium sulphate dihydrate whisker. After calcium sulphate dihydrate whisker is deposited from calcium nitrate solution, calcium chloride solution or the mixed solution of calcium nitrate and calcium chloride are deposited, the water solution is translated to be nitric acid solution, hydrochloric acid solution or a mixed solution of nitric acid and hydrochloric acid, returning back to leaching out or treating process for processing non-ferrous metal mineral substance, non-ferrous metal secondary resource or electroplating remove. The calcium sulphate dihydrate whisker is treated by microwave heating, forming calcium sulfate hemihydrate or anhydrous sulphate of calcium after dehydration.

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.

A reinforced wallboard core is prepared from a slurry comprising a mixture of β-calcium sulfate hemihydrate, a cellulose ether additive other than CMC and an amount of water that is sufficient to form a slurry and resulting in a wallboard density of less than 0.8 g/cc. The β-calcium sulfate hemihydrate is hydrated by the water forming a wallboard core reinforced by the cellulose ether additive. The cellulose ether, having a molecular weight of at least about 20,000 and a viscosity grade of at least about 100 cps, is selected to give the reinforced wallboard core improved nail pull resistance and greater flexural strength than unreinforced wallboard of the same density. The reinforced wallboard core may be used for reduced-paper wallboard and/or for lightweight wallboard, for example.

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.

A slurry is made including water, at least 50% by weight calcium sulfate hemihydrate, and a specific polycarboxylate dispersant prepared using at least three repeating units. A first repeating unit is a vinyl ether-type repeating unit. A second repeating unit includes a maleic acid-type repeating unit. A third repeating unit includes an acrylic acid-type repeating unit. The polymer dispersant has a molecular weight of from about 20,000 to about 80,000 Daltons. The slurry made from this composition can be made at reduced water levels to speed drying and reduce drying costs.

A foundation system includes metal framing members that support a reinforced, lightweight, dimensionally stable cementitious panel. The foundation system is non-combustible, water durable, mold and rot resistant, and termite resistant. The panels employ one or more layers of a continuous phase resulting from the curing of an aqueous mixture of inorganic binder, for example, calcium sulfate alpha hemihydrate, hydraulic cement, an active pozzolan and lime. The continuous phase is reinforced with glass fibers and contains lightweight filler particles, for example, ceramic microspheres.

The invention discloses a preparation method of calcium sulfate hemihydrate crystal whiskers high in length diameter ratio. The method includes firstly subjecting soluble inorganic calcium salt and inorganic sulfate to coprecipitation at the temperature of 10-90 DEG C, activating for 1-6 hours at the temperature of 40-150 DEG C to obtain a precursor after filtering and washing, adding the precursor into a hydrothermal medium with crystal form control agent for hydrothermal treatment for 2-10 hours at the temperature of 80-180 DEG C, washing, filtering and drying hydrothermal products, and then obtaining calcium sulfate hemihydrate crystal whiskers in the diameter of 0.1-4 micrometers, the length of 20-3000 micrometers and the length diameter ratio of 50-1000, uniform in shape and identical in size. The preparation method is simple, mild in conditions and low in cost of materials which are easy to obtain, and is easy to industrially popularize. The main content of the calcium sulfate hemihydrate crystal whiskers prepared by the preparation method is larger than 98%, and the calcium sulfate hemihydrate crystal whiskers are uniform in shape and diameter and high in additional value and can be expectedly used as high-performance reinforcing materials for the industries of ceramics, plastics, rubber and paper making and the like.

A composition is disclosed for a mixture to be used in conjunction with water for preparing a slurry that hydrates to form a high strength flooring compound. The mixture includes from about 50% to about 98% by weight calcium sulfate hemihydrate. A three repeating unit polycarboxylate dispersant is included in the mixture in amounts from about 0.2% to about 10% by weight. The repeating units include a polyether repeating unit, an acrylic acid-type repeating unit and a maleic acid-type repeating unit. A modifier that enhances the efficacy of the dispersant is also a component of the mixture. When combined with recommended amounts of water, a slurry is formed that is useful as a flooring composition.

A plaster composition for making molds for reproduction by casting is disclosed. Calcium sulfate hemihydrate, potassium sulfate and potassium sodium tartrate are mixed together. The potassium sulfate and potassium sodium tartrate are in a ratio of from about 1:1 to about 10:1. Potassium sodium tartrate is present in an amount of from about 1 to about 10 pounds per ton of dry calcium sulfate hemihydrate, and the total of the potassium sulfate and potassium sodium tartrate is from about 2 to about 35 pounds per ton of calcium sulfate hemihydrate. Methods of making and using molds of this composition are also disclosed.

The present invention provides a floor underlayment cement composition comprising at least about 95% by weight, based on the weight of the composition, of a hydraulic cementitious mixture and at least about 0.03% by weight, based on the weight of the composition, of a superplasticizer. The hydraulic cementitious mixture includes in the range of from about 35% to about 65% by weight, based on the weight of the mixture, of ground, granulated blast furnace slag, and in the range of from about 35% to about 65% by weight, based on the weight of the mixture, of a gypsum component selected from the group consisting of alpha-calcium sulfate hemihydrate, beta-calcium sulfate hemihydrate and mixtures thereof. It is not necessary to include Portland cement or aluminous cement in the hydraulic cementitious mixture. A floor underlayment slurry and a method of forming a high strength floor underlayment on a floor substrate are also provided.

The invention discloses a preparation method of high-reinforcement modified anhydrous calcium sulfate crystal whiskers. The method comprises the following steps that: firstly, limestone powder is added into stirred water to be prepared into calcium salt aqueous emulsion; then, sulfuric acid and crystal modifiers are sequentially added into the stirred water to be prepared into sulfuric acid water solution; next, the calcium salt aqueous emulsion containing 1 mol part of Ca<2+> is added into the sulfuric acid water solution containing 2 mol parts of SO4<2-> with the temperature reaching 100 to 110 DEG C, then, morphology control agents are added, the materials are subjected to stirring and aging for 2 to 3.5 hours under the temperature condition being 110 to 120 DEG C, leaching and washing are carried out, and calcium sulfate hemihydrate crystal whisker wet products are obtained; the calcination drying finally is carried out under the temperature condition higher than 200 DEG C to obtain the anhydrous calcium sulfate crystal whiskers; and then, the surface modification treatment is carried out to finally obtain the high-reinforcement modified anhydrous calcium sulfate crystal whiskers. The preparation method has the advantages that the product quality is high, the cost is low, the preparation process is short, the reaction condition is mild, and in addition, green and environmental-friendly effects can be realized.

A solid implantable bone construct (12) shaped like a cylinder, a cone, or a frustum, for anchoring ligament implants. The bone construct (12) can include a bone component and a biocompatible solid component. The bone component can include particulate bone of between 75 and 600 microns, powdered bone of 75 microns or smaller in size, or both. The biocompatible solid component can include calcium sulfate hemihydrate, a calcium phosphate product, or both. The bone component can be between 5 and 50 wt-% of the construct (12) and the biocompatible solid component can be at least 50 wt-% of the construct (12). Also disclosed is a composite graft (10) comprising a first bone dowel (12) and a ligament (20) and a method of securing one bone to another using the composite graft (10).

An improved gypsum slurry that includes water, calcium sulfate hemihydrate, a naphthalene sulfonate dispersant and a modifier. The modifier is chemically configured to improve the efficacy of the naphthalene sulfonate dispersant. Preferred modifiers include cement, lime, slaked lime, soda ash, carbonates, silicates and phosphates.

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 dust-reducing building panel is made by selecting a dedusting agent that is a solid at room temperature but that melts to form composite particles by at least one of agglomerating and surface adsorption of fines under conditions selected from the group consisting of cutting, abrading or sanding. The dedusting agent is used to make a slurry including water and a hydraulic material selected from the group consisting of calcium sulfate hemihydrate and cement. After the slurry is made, it is deposited onto a facing material and formed into a panel. The building panel is then allowed to set. Some embodiments of the building utilize a dedusting agent that includes natural or synthetic waxes.