Abstract: A process for separating lead includes the steps of dissolving a water insoluble lead salt in an acetate solution and precipitating the lead by treating the acetate solution with a sulfite so as to form an insoluble lead sulfite. The acetate is recovered by concentrating the solution and precipitating the acetate therefrom, drying the acetate crystals and dissolving them in methanol. The methanol is then evaporated leaving purified acetate crystals. The process is shown as part of a precious metal recovery system in the treatment of tankhouse slime.

Abstract: A method of separation by fractional crystallization from a liquid mixture in which the liquid mixture is repeatedly passed in turbulent flow through an indirectly cooled crystallization zone, which must be kept full. The liquid remaining after deposition of a layer of crystals on the wall of the crystallization zone is removed, whereupon the surface of the layer of crystals is washed and the crystals are melted by passing a melt of similar compositions to that of the layer of crystals through the crystallization zone. During crystallization the melt is maintained at the temperature of crystallization and crystallization is stopped when the frozen fraction is from 70 to 98%.

Abstract: A method for processing a sulfidic zinc source to recover metallic zinc wherein the source is leached with an electrolysis cell acid, the leaching product is separated into a liquor and a primary leaching residue, followed by drying and smelting of the dried leaching residue. The improvements of the present invention are directed primarily to the treatment of the liquor recovered from the leaching stage, and involve crystallizing out Fe.sup.2+ from the liquor as a ferrous sulfate hydrate in a crystallization stage, separating the filtrate from the crystallization stage in a first separation stage to produce a filtrate and a residue, neutralizing and oxidizing the separated filtrate from the crystallization stage to precipitate the remaining Fe.sup.2+ in a precipitation stage, separating the filtrate from the precipitation stage in a second separation stage and purifying the separated filtrate from the second separation stage before passing it to the electrolysis cell.

Abstract: A method of obtaining crystals of a solute in which the fresh solution is initially cooled by contacting with a mother liquor containing crystals below the desired grain size to produce a mother phase in a state of incipient crystallization. The latter is crystallized with or without further cooling by passing it through an elongated crystallizer body with angularly adjoining portions swung around an offset axis and having cooled walls. The resulting slurry is then continuously filtered to separate out the crystals of the required size and form the mother liquor containing particles below the required size.

Abstract: The present invention relates to a process for the production of either electrolytic zinc or high purity zinc salts from secondary zinc raw materials which comprises: leaching said raw material in a slightly acid aqueous solution at controlled pH, separating the reaction mixture into a leaching liquor containing the leached zinc and a solid residue which after suitable washing is descarted; directing the zinc-bearing liquor to a solvent extraction facility where it is brought into contact with an organic solution containing organic acids as cationic extraction reagents, by means of which, an ion exchange of zinc by hydrogen ions is achieved, resulting in a zinc loaded organic solution and in an aqueous solution containing the stoichiometric acidity to the extracted zinc; recycling the acid aqueous raffinate to the previous leaching step where it is used as the slightly acid aqueous solution to carry-out the zinc leaching from the raw material; sending the zinc organic extract to a stripping facility where it

Abstract: The product which is present in the form of a melt is cooled and thereby crystallized in a double-shaft worm machine which has self-cleaning worm shafts rotating in the same direction. The crystallizing material is continually crushed in a repeatedly cutting manner during solidification and during the subsequent cooling operation, while maintaining the main transporting direction in the worm. In this manner, crystal agglomerates are prevented from forming which have only solidified on the surface, while still containing liquid portions inside. The process is carried out using a worm machine, the worm profile of which is repeatedly interrupted by introducing grooves, so that only small segment ridges remain.

Abstract: The present invention relates to a process for the separation of boric acid from boric acid-containing sulphuric acid in which the concentration of the sulphuric acid is adjusted such that the boric acid precipitates therefrom.

Abstract: The present invention relates to the production of high-purity substances and, more specifically, to a process for a fine purification of sulphur hexafluoride from impurities.The process for a fine purification of sulphur hexafluoride comprises purification of sulphur hexafluoride by crystallization at a speed of displacement of the interphase boundary of from 1 to 50 mm/hr at a temperature of from 222.3 to 217.degree. K.; the liquid-phase concentrate formed during crystallization is subjected to sublimation purification under a pressure of from 210 to 1.3-0.13 KPa.The high-purity sulphur hexafluoride is useful in the high-voltage energetics as an insulation and arc-exctinguishing medium, as well as in electronics, laser engineering, metallurgy and medicine.

Abstract: Large surface silicon crystal layers with a columnar structure are produced by directing a plurality of spaced-apart cooling gas streams arranged relative to one another to correspond to a desired columnar structure and positioned a relatively short distance above a free surface of a silicon melt surface located below such system so that a spontaneous seed crystal formation occurs at the regions or areas of the melt immediately below each gas stream and thereafter the affected melt surface is solidified, and then removing the so-formed plate or disc-shaped silicon body from the melt. Dopant material can be incorporated within the so-formed plate or disc-shaped silicon crystal so that a pn-juncture parallel to the surface of such plate or disc is attained.

Abstract: A feed of lipid and solvent is concentrated in a chamber by establishing and maintaining within a chamber a net major flow and a separate and distinct net minor flow. A net transfer of solid phase lipid is effected from the major internal flow to the minor internal flow thereby concentrating the minor flow. However, the minor flow is preferably essentially all in liquid phase when it is withdrawn from the chamber.

Abstract: A method of removing phosphorous impurity in a process for purifying silicon wherein silicon is crystallized from a solvent metal is disclosed. The method comprises the steps of providing a molten body containing silicon, the remainder aluminum and impurities, and treating the body with a source of chlorine to remove phosphorous therefrom.

Abstract: A method of removing boron impurity in a process for purifying silicon is disclosed wherein silicon is crystallized from a solvent metal. The method comprises the steps of providing a molten body containing silicon, the remainder aluminum and impurities and providing a metal selected from the group consisting of titanium, vanadium and zirconium therein, the metal from the group forming a reaction product with boron and permitting the reaction product to settle in the body for removal purposes.

Abstract: A method for purifying silicon comprises the steps of providing a body of molten silicon-rich material and extracting heat therefrom to provide a solid phase containing silicon in crystal form and to concentrate impurities in a molten phase. After a desired amount of heat has been extracted, a substantial part of the molten phase is separated from the solid phase. A fraction or portion of the solid phase is remelted for purposes of removing solvent metal, including impurities, from the crystals, and at least one fraction of the remelted material is separated from the crystals.

Abstract: A method for purifying silicon comprises the steps of providing a body of molten silicon-rich material in a vessel having an upwardly removable first bottom therein and extracting heat therefrom to provide a solid phase containing silicon in crystal form and to concentrate impurities in a molten phase. After a desired amount of heat has been extracted, a substantial part of the molten phase is separated from the solid phase. A fraction or portion of the solid phase is remelted for purposes of removing solvent metal, including impurities, from the crystals, and at least one fraction of the remelted material is separated from the crystals. The crystals are removed from the vessel by upwardly withdrawing the removable bottom.

Abstract: A method and apparatus for outgassing raw materials includes the steps of and means for heating the material to a temperature of about 800.degree. C. and maintaining that temperature for a first bake out period during which the material is maintained at a pressure of about 200 millitorr and for a second bake out period during which the material is maintained at a pressure of about 5 millitorr or less. During the first bake out period, an inert gas is backstreamed through the raw material.

Abstract: The invention contemplates a process for the crystalline precipitation of a chromogen from solution thereof in a solvent and within a capillary. The process involves first initiating a course of crystalline precipitation of the chromogen by initially and locally supersaturating the solution within the capillary, and thereafter evaporating the solvent at a rate and in an environment sufficient for further crystallization to proceed unimpeded by local supersaturation.

Abstract: A method for purifying silicon comprises the steps of providing a body of molten silicon-rich material and extracting heat therefrom to provide a solid phase containing silicon in crystal form and to concentrate impurities in a molten phase. After a desired amount of heat has been extracted, a substantial part of the molten phase is separated from the solid phase. A fraction or portion of the solid phase is remelted for purposes of removing solvent metal, including impurities, from the crystals, and at least one fraction of the remelted material is separated from the crystals.

Abstract: A modular chlorine dioxide generating unit (10) is disclosed wherein recycled reaction mixture passes along a flow path (18) internally of the generator vessel (12) out of direct fluid flow communication with the reaction medium (13) from the lower end (16) of the vessel (12) to a discharge point in the vapor phase (15 ) above the liquid level (13) in the generator vessel (12).

Abstract: To remove salts from a solution containing the salts, hot air is injected downwards into the solution in a concentrator, and the solution is concentrated by direct contact with the hot air, thereby enhancing an evaporation efficiency in the concentrator and preventing scale deposition in the concentrator and piping system. The solution is forcedly cooled in a crystallizer by direct contact with cool air, thereby making crystals grow in the solution within a short time. The solution and air are circulated in a closed cycle, thereby preventing a secondary environmental pollution.

Abstract: A method for purifying silicon comprises the steps of providing a body of molten silicon-rich material and extracting heat therefrom to provide a solid phase containing silicon in crystal form and to concentrate impurities in a molten phase. After a desired amount of heat has been extracted, a substantial part of the molten phase is separated from the solid phase. A fraction or portion of the solid phase is remelted for purposes of removing solvent metal, including impurities, from the crystals, and at least one fraction of the remelted material is separated from the crystals.

Abstract: A process for purifying solid substances by melting and subsequent resoliication, wherein a melted bath of the solid substance is formed, a roller is placed in the bath so that a first portion of its surface is in contact with the melted substance, and the surface of the roller is cooled to a temperature below the melting point of the solid substance. The cooled roller is rotated in the melted substance to collect a solidified film of the substance on the roller surface. A second portion of the roller surface is passed through a heated zone at a temperature above the melting point of the solid substance, so that the solidified film is remelted and collected in an appliance.

Abstract: Silicon platelets essentially free of iron are precipitated from a solution of metallurgical grade silicon in molten aluminum and are melted in contact with silica slag to produce a refined metallurgical silicon (RMS). By directionally solidifying the refined silicon-slag melt, a directionally solidified refined metallurgical silicon (DS/RMS) is separated from a region of solidified melt having a high concentration of impurities rejected by the silicon as it solidifies. The resulting RMS and DS/RMS materials are low-cost, multigrained products having a substantially higher impurity content than in conventional high purity semiconductor grade silicon while, at the same time, have suitable properties for desirable solar cell and other silicon applications.

Abstract: A method of manufacturing semiconductor devices comprising a layer of semiconductor material, comprising the steps of providing a strip-shaped solid substrate having a main surface and providing a solid support having a substantially horizontal surface and comprising a substantially floating liquid mass of such semiconductor material on the substantially horizontal surface, the main surface being wettable by the liquid semiconductor material. The liquid mass is contacted with the main surface of said substrate, onto which substrate the layer of semiconductor material is to be provided, the substrate is moved in its longitudinal direction along and in contact with said liquid mass so that a liquid layer of said semiconductor material is formed on said strip and taken along with it, and the liquid layer is substantially progressively solidified.

Abstract: The transfer of agitational forces from a main vessel to an elutriation leg connected thereto is effectively minimized with a slurry inlet and liquor outlet device mounted in the upper end of the elutriation leg. The device includes a slurry flow directing member which receives the gravitational flow of slurry from the main vessel and directs such flow in a downward path of reduced cross-sectional area with respect to the cross-sectional area of the elutriation leg for impingement onto a target member mounted below the slurry flow directing member. The downward slurry flow is radially outwardly deflected by the target member to substantially reduce the concentrated downward forces of the slurry which would otherwise tend to disrupt or restrict the formation and maintenance of a fluidized bed in the elutriation leg.

Abstract: A process for producing crystalline silicon having an iron concentration less than about one-twentieth of the iron concentration of the mother liquor. Iron contaminated silicon is introduced into a mold and the mold walls are maintained at a temperature sufficient to cause silicon crystalline growth. The mother liquor is agitated to wash the exposed surfaces of the growing silicon crystals and to prevent the freezing of the top surface of the mother liquor. A hollow crystalline silicon ingot is formed and both the inner zone centrally of the crystalline ingot and the outer zone adjacent to the mold wall are removed leaving an inner zone having an iron concentration less than one-twentieth of the iron concentration of the original mother liquor.

Abstract: A method and apparatus for recovering flux salt and recycling or reusing the same in an aluminum refining method by introducing salt brine into a cylindrical evaporator with hot evaporator gas, rotating the evaporator to expose the brine to the hot gas and removing the slurry from the evaporator.

Abstract: A crystallizable solute is crystallized from a solution containing the same by introducing a solution of said solute into a first stage evaporative-crystallization zone together with seed solute crystals. Within the first stage evaporative-crystallization zone the solution is concentrated to yield a saturated first stage concentrate containing crystals of said solute. The crystals of said solute are substantially larger than said seed crystals and are suspended in a solution more concentrated with respect to said solute than the solution supplied to said first evaporative-crystallizaton zone. A stream of said first concentrate is removed from said first evaporative-crystallizaton zone and transferred to a second evaporative-crystallization zone for further concentration or crystallization of solute and for the production of solute crystals of increased size.

Abstract: A system for the conversion of liquid phases of non-metallic substances into solid phases, especially polymerizable or crystallizable substances, provides a reaction chamber in the form of an upstanding substantially tubular-shaped hollow body, at the upper end of which there is introduced the liquid phase and at the lower end of which there is continuously withdrawn the solid phase. The reaction chamber is enclosed at least at its upper region containing the liquid phase by a jacket of polygonal cross-section, wherein the wall sections of the chamber which in cross-section is polygonal are formed in each case by a run of an endless band which bears against the associated jacket section, each such band moving continuously downwardly by means of the aforesaid run and being substantially synchronously driven with the remaining bands.

Abstract: Soft hexagonal boron nitride crystals of 200-600 microns platelet size are produced from crystals of less than fifty microns particle size by mixing the small crystals with Li.sub.3 N, simultaneously heating and pressurizing said mixture to a temperature and pressure in a restricted region of the graphitic (hexagonal) boron nitride (GBN) stable region of the pressure-temperature (P-T) phase diagram of boron nitride, cooling and depressurizing said mixture, and separating off the water soluble material present in the mixture to leave a residue of large crystals of boron nitride.

Abstract: Hexagonal plate crystals of aluminum sulfate are produced in chemically pure form by a process which comprises cooling a heated saturated solution of chemically impure aluminum sulfate acidified with sulfuric acid to precipitate crystals of aluminum sulfate, heating the slurry of the cooled solution containing the precipitated aluminum sulfate crystals to a predetermined temperature wherein the temperature is maintained for a time sufficient to dissolve a portion of the crystals in the solution, cooling the heated slurry to precipitate aluminum sulfate crystals, and separating the precipitated crystals from the slurry.

Abstract: A recrystallized menthol product derived from crude natural menthol is described for incorporation into foods, beverages and tobacco in amounts sufficient to create a lingering cool sensation in the mouth of the user of the food, beverage or tobacco with little or no taste of menthol. The recrystallized menthol product is recrystallized from an ethanol-water solution of crude natural menthol under specific conditions.

Abstract: Crystals are grown in a column through which a supersaturated solution flows upwardly while large crystals having one dimension substantially greater than another dimension taken from the bottom of the column are fractured externally of the column and the fractured particles are returned to the upper end of the column where fines are separated from larger seed type particles.

Abstract: A process is described for purifying liquids by cryogenic sublimation. This process involves solidifying the liquid by reducing the temperature and pressure to below the triple point. Purification is then carried out by direct transformation from the solid to the vapor phase. Because of increased differentials in vapor pressures at the low temperature at which the procedure is carried out, this purification process is highly efficient and is also particularly suitable for liquids that are susceptible to decomposition with ordinary purification procedures requiring elevated temperatures. The procedure is also advantageous in separating azeotropes, structurally similar compounds, as well as treating flammable, hydroscopic, corrosive and fuming compounds.

Abstract: A tartarous beverage, such as wine, containing a tartrate to be removed therefrom is conveyed from a storage container through a conduit under pressure into a first module having a semipermeable membrane. The semipermeable membrane forms two streams, a tartrate-free permeate and a concentrate containing a solution of said tartarous beverage and tartrate. The permeate stream is directed from the module through a conduit to a delivery tank. The concentrate may then be conveyed from the first module to a plurality of modules that are serially connected to each other. Each of the modules has an outlet that is connected by an intermediate conduit to an inlet of the adjacent module for the passage of the solution therethrough. The permeate stream exits from each of the modules and is collectively conveyed to the delivery tank. The concentrate is directed through the modules to provide a stronger concentration of the tartrate in the solution.

Abstract: A continuous integral forced circulation cooling crystallizer for the processing of fluids which comprises, in vertical disposition:A. an upper fluid holding chamber having an inlet and outlet for the fluid to be processed and having a partition means vertically disposed therein to provide an inlet section and an outlet section, the partition means being positioned so as to permit fluid flow between the sections at the lower region;B. a heat exchange chamber comprising a multiplicity of separate vertically disposed tubular elements a fluid inlet and outlet to permit the flow of a heat exchange fluid through the extra-tubular portion of the chamber, and a multiplicity of horizontally disposed baffles adapted to direct the flowof the heat exchange fluid through the extra-tubular portion of the heat exchange chamber; and flow ofC.

Abstract: An improved freeze refining method including the steps of collecting a heterogeneons material in crystalline form from a heated melt containing pure and impure materials and removing the collected crystals while maintaining the integrity of the crystals.