Abstract: A carbon dioxide clathrate having a lump diameter enough to precipitate on a desired abyssal position of the sea without being drifted by a seawater flow of the abyss can be produced by bringing an aqueous solution into contact with carbon dioxide with the interposition of an interface in a reactor and retaining this contact; adjusting the pressure in the reactor to 13 atm or more, the temperature of the aqueous solution to a level of more than 5.degree. C. to 10.degree. C., the temperature of the interface to a level of more than 10.degree. C. to 15.degree. C. and the temperature of a lug inserted into the aqueous solution to a level of more than 0.degree. C. to 5.degree. C.; producing/growing the carbon dioxide clathrate on the lug; and then heating the lug to a temperature of more than 10.degree. C. to 30.degree. C. to separate/drop the carbon dioxide clathrate therefrom.

Abstract: Disclosed is a method for recrystallizing solid materials (e.g. RDX) from systems comprised of a solute, which is the eventual material recrystallized, a liquid which is a suitable solvent for the solute, and a gaseous component which is soluble within the solvent and whose presence therein causes the solvent to approach or attain a supersaturated state, thereby precipitating (recrystallizing) the solute material. By control of process parameters (pressure, temperature, time, and rate, rate of injection of gas, etc.) the operator can influence the properties of the material recrystallized.

Abstract: The invention provides novel polymeric and non-polymeric, liquid crystal type, chemical salt complexes of aroyl acids and monovalent and polyvalent metals. They are formed by covalent and coordinate bonding for use as electrical superconductors, as electrolytes in alkali metal batteries, electrochromic windows, static dissipative polymers, etc. The invention also provides processes for manufacturing such complexes, including the in situ formation in and on various metals and oxides. The processes also include the use of supercritical solvents such as carbon dioxide to solubilize the complexes for introduction into plastics and inorganic superconductors. The chemical complexes include the triads formed of liquid crystal aroyl salts, non-polymeric ligand solvents, and polymeric aroylacrylate salts. Both homopolymer and copolymer complexes of the metal aroylacrylates may be prepared and the latter may be cross-linked.

Abstract: The invention provides novel chemical complexation products for use as superconductors, polymer electrolytes for alkali metal batteries, electrolytes for electrochromic windows, static dissipative plastics, etc. It also provides for manufacturing such complexation products. The complexation products may comprise (a) lyotropic liquid crystal salts ordinarily insoluble in anhydrous, aprotic, ligand-type solvents, (b) non-polymeric ligand-type solvents containing the NCO group, (c) polymeric-type ligands containing repetitive, oxygen-bearing groups along a substantially linear chain, and (d) from 1% to 98% by weight of inorganic compounds of high surface area. The complexation and solubilization can be carried out so as to secure liquids or low viscosity pastes by heating and mixing the components in appropriate ratios.

Abstract: A process is provided for the separation of substances by melt crystallization. The organic mixtures which are difficult to crystallize are heated to a temperature sufficient to obtain a melt with the melt then being moved through a three-dimensional crystallization matrix having a large specific area. The melt is slowly cooled over a temperature range so as to achieve a selective crystallization from the supersaturated melt in the carrier matrix. A deposited crystal phase is thereafter melted and separated from the carrier matrix and removed by centrifugation. The carrier matrix may have a crystallization-promoting microstructure surface and may consist of an openpored foam.

Abstract: An endless steel band or belt (12) moves upwardly (see arrow 65). The upper length or run (17) of the band or belt (12) is cooled or heated by a fluid flowing from nozzles (43, 59). A feeding station (21) supplies a liquid mixture which mixture runs downwardly along the crystallizing surface (11) of the belt. A crystal layer is thus formed on the crystallizing surface 11. This crystal layer is moved upwardly in counter-current. The remaining liquid, the mother liquor, which is substantially free from crystallizable substance, flows downwardly. A device (22) for changing the inclination angle (.alpha.) of the crystallizing surface permits the crystallizing device to be adjusted in a simple way in accordance with the requirement of the crystallizating process. For automatic operation, a control unit (C) can associate the angle of inclination (.alpha.

Abstract: Ammonium carbamate, in solution with urea, water and ammonia and under high temperature and pressure is cooled to below its crystallization temperature while being subjected to an elevated pressure. The crystallized substance formed is then dried, crushed, and pelletized with the aid of a binding agent to produce pellets having substantial strength and stability, and having particular utility as a deicer for roadways.

Abstract: Impinging fluid jet streams are used in a continuous crystallization process to achieve high intensity micromixing of fluids so as to form a homogeneous composition prior to the start of nucleation. This process permits direct crystallization of high surface area particles of high purity and stability.

Abstract: A process for the preparation of a quaternary ammonium bisulfate which comprises the reaction of a quaternary ammonium alkylsulfate with sulfuric acid in a solvent mixture comprised of water and isopropyl alcohol, followed by the recovery of the solid quaternary ammonium bisulfate by crystallization from the reaction mixture.

Abstract: The subject of the invention is a process for separating silicic compounds from baths for cleaning steel substrates containing iron ions and silicic compounds, consisting of the following stages:a) a concentrated spent cleaning bath is cooled in a controlled manner to a temperature below 60.degree. C. so as to precipitate the silicic compounds,b) the cleaning bath is allowed to cool for at least 2 hours,c) the cleaning bath is reheated,d) the silicic compounds precipitated from the cleaning bath are separated off.

Abstract: Process and installation for crystallising an inorganic substance in a fluidised bed of crystals (14), which is generated by subjecting a solution supersaturated in the substance to be crystallised to an ascending circulation across a distributor (12), located below the bed (14), of a fluidised-bed reactor, a fraction (22) of the supersaturated solution being taken off upstream of the distributor (12) and being recycled downstream of the distributor (12) into the fluidised bed (14) or into the mother liquor from the crystallisation, and the mother liquor being supersaturated for reconstituting the said supersaturated solution.

Abstract: A method of crystallizing plastic such as polyethylene terephthlate in the form of small particles comprises the steps of placing the particles in a liquid bath such as water, agitating the bath using jets of hot gas such as steam while simultaneously raising the temperature of the particles to a level at which the plastic crystallizes to a predetermined level of crystallinity. The particles are thereafter separated from the bath and dried.

Abstract: A method of growing crystals utilizing the temperature dependence of solubility of a crystalline material which is characterized in that crystals are deposited by locally controlling the temperature of a solution containing the crystalline material to take a suitable value. Larger crystals can be formed.

Abstract: A melt is crystallized by introducing the melt into a gap formed between two belts. The gap-forming flights of the belts travel in opposite directions. An upper one of the flights is cooled so that an upper surface of the melt crystallizes thereon and is removed from the gap on the upper belt. The lower belt removes the residual melt from the gap and that residual melt is recycled to the gap.

Abstract: A method for controlling the crystallization of protein by solvent evaporation including placing a drop of protein solution between and in contact with a pair of parallel plates and driving one of the plates toward and away from the other plate in a controlled manner to adjust the spacing between the plates. The drop of solution forms a liquid cylinder having a height dependent upon the plate spacing thereby effecting the surface area available for solvent evaporation. When the spacing is close, evaporation is slow. Evaporation is increased by increasing the spacing between the plates until the breaking point of the liquid cylinder. One plate is mounted upon a fixed post while the other plate is carried by a receptacle movable relative to the post and driven by a belt driven screw drive. The temperature and humidity of the drop of protein solution are controlled by sealing the drop within the receptacle and mounting a heater and dessicant within the receptacle.

Abstract: A method and an apparatus for controlling reactant ion concentration within a precipitation vessel to optimize the reactions occurring therein is disclosed. In one important implementation, the reactant controlled comprises halide ion in a reactor during the precipitation and growth of silver halide grains. In this embodiment, the method includes measuring the amount of halide ion within the precipitation vessel; measuring the flow rates of the halide feed stream and the silver feed stream; storing the measured halide ion concentration and measured feed stream flow rates; computing an estimated smoothed halide ion concentration value as a function of the stored measured halide ion concentration and measured feed stream flow rates; and adjustably controlling the amount of halide ion added to the precipitation vessel as a function of this estimated halide ion concentration value.

Abstract: A multistage process for the separation and purification of a desired crystalline material by repeated dissolution and recrystallization, wherein crystals and solvent move countercurrent to one another through the stages. A fluid temperature gradient is maintained within each recrystallization unit to make use of convection to facilitate or accelerate concurrent dissolution and recrystallization within a single vessel. Solid recrystallized material is moved from one unit to the next unit. An automated apparatus and a manually operated apparatus for carrying out the process are also described.

Abstract: A method for fast cooling granules of low melting point, subliming substances obtained by a prilling process. The granules are in the shape of a plurality of droplets having diameters of 0.5. to 4 mm and are formed from a prilling column with the droplets partially solidified by means of a countercurrent air cooling. The partially solidified particles are received in an inert liquid in which the substance is insoluble. The liquid also has a lower boiling point than the melting point of this substance. The solidified particles are separated from the liquid before being completely cooled so that their remaining heat content evaporates any residual liquid from the particles.

Abstract: A process is provided for the separation of substances by melt crystallization. The organic mixtures which are difficult to crystallize are heated to a temperature sufficient to obtain a melt with the melt then being moved through a three-dimensional crystallization matrix having a large specific area. The melt is slowly cooled over a temperature range so as to achieve a selective crystallization from the supersaturated melt in the carrier matrix. A deposited crystal phase is thereafter melted and separated from the carrier matrix and removed by centrifugation. The carrier matrix may have a crystallization-promoting microstructure surface and may consist of an openpored foam.

Abstract: An apparatus for forming silver halide grains comprises a reaction vessel for causing the nucleus formation and the crystal growth of silver halide grains. The apparatus further includes: a mixer disposed outside of the reaction vessel and having a high-speed stirring blade; conduits for supplying an aqueous solution of a water-soluble silver salt, an aqueous solution of water-soluble halide, and an aqueous protective colloid solution to the mixer while controlling the rotational speed of the high-speed stirring blade to form fine, silver halide grains; and a conduit for connecting the mixer to the reaction vessel for immediately supplying the fine grains in the mixer to the reaction vessel.

Abstract: Gravitational phenomena, including convection, sedimentation, and interactions of materials with their containers all affect the crystal growth process. If they are not taken into consideration they can have adverse effects on the quantity and quality of crystals produced. As a practical matter, convection and sedimentation can be completely eliminated only under conditions of low gravity attained during orbital flight. There is, then, an advantage to effecting crystallization in space. But in the absence of of convection in a microgravity environment cooling proceeds by thermal diffusion from the walls to the center of the solution chamber. This renders control of nucleation difficult. Accordingly there is a need for a new and improved nucleation process in space. Herein crystals are nucleated by creating a small localized region of high relative supersaturation in a host solution at a lower degree of supersaturation.

Abstract: Disclosed is a process for preparing crystals of anhydrous sodium sulfide, the process being characterized in that the process comprises the steps of heating crystals of polyhydrate of sodium sulfide under a pressure of about 500 torr or less at a temperature varying not more than .+-.about 10.degree. C. from the phase transition point between polyhydrate crystals and monohydrate crystals of sodium sulfide for about 2 hours or longer and further heating the monohydrate under atmospheric or reduced pressure at about 90.degree. to about 200.degree. C. for about 2 hours or longer.

Abstract: The invention relates to a process in which a melt is mixed with, and emulsified in a colder aqueous phase at a temperature below the crystallization point of the molten compound, the melt only solidifying in the form of the dispersed particles after the emulsification step. To this end, the melt is sprayed into the aqueous phase to form a preliminary emulsion (12) and the preliminary emulsion is finely dispersed for 0.005 s to 0.15 s in a following homogenization nozzle (8) to form an emulsion (15) which then solidifies to form the final crystal suspension. The particle size can be clearly and reproducibly adjusted through the nozzle pressure during the emulsification step. The process may be used in particular for the production of highly concentrated dispersions of high-melting organic materials.

Abstract: A method and apparatus are provided for superpurifying crystallizable substances to a purity level of 99.999 percent. Included is controlling the reflux ratio by controlling and/or metering transfers of crystals and mother liquor at selected locations and by maintaining a steady state of transfers between a plurality of stages that carry out similar operations.

Abstract: A process for the preparation of a single crystal of a biopolymer by growth from a solution, which comprises continuously changing one factor having an influence on the conditions for crystallization of a solution of a biopolymer, fractionating the solution, and independently crystallizing the resultant fractions. The process may be carried out by an apparatus comprising a means for feeding a crystallizing agent solution, a means for feeding a biopolymer solution, a means for producing a series of changes of predetermined crystallization conditions, said means continuously changing at least one factor having an influence on the conditions for crystallization of the biopolymer solution, and means for fractionating the solution and independently crystallizing the resultant fractions.

Abstract: In the process for the separation of substances by cooling crystallization, the mixture remaining in the crystallizer after separation of the crystal layer is removed and the crystal layer is melted. The process is distinguished in that the mixture, which completely fills the crystallizer, is set into vibration during the process of solidification by movements of oscillation imparted to it and is left in the crystallizer until a degree of solidification of from 50% to 90% has been obtained.

Abstract: A crystallographic observation apparatus for the observation of behavior of crystals under pressure and for the measurement of the crystallization pressure and pressure of fusion of substances. The apparatus comprises a pressure chamber having a cavity and provided with a transparent observation window or windows, a pressurizing device for pressurizing the cavity of the pressure vessel, and small, entirely or partly transparent, entirely or partly elastic sample containing means for containing a sample, provided within the cavity of the pressure vessel. The sample can easily be changed for another sample simply by changing the sample containing means containing the former sample for another sample containing means containing the latter sample, or the apparatus can easily be cleaned after the completion of observation of a sample for the observation of the next sample, simply by washing the sample containing means.

Abstract: A mass constituted by glucose syrup and anhydrous dextrose crystals is led to pass through from top to bottom and with malaxation of crystallization zone 1 of axis preferably substantially vertical in which said mass is subject to a temperature gradient globally decreasing by 0.2.degree. to 2.degree. C./hour from top to bottom possibly modulated, said zone being supplied through pipe 2 with glucose syrup and through pipe 7 with mass subject to crystallization M taken up at 8 and recycled at 9.

Abstract: The invention relates to a crystallization process for recovering a pure substance from a liquid mixture, a starting mixture being cooled down in a crystallization zone to form a crystal suspension from which crystals of the pure substance are recovered, wherein a) the crystal suspension is subjected to a crude preliminary separation in a (preliminary) separation zone to form a first mother liquor and a crystal mass containing relatively small particles, b) the crystal mass formed in a) is allowed to develop in a development zone at a temperature which is higher than that of the crystallization zone and lower than the melting point of the substance to be recovered, and is separated into a developed crystal mass and a second mother liquor, and c) the developed crystal mass formed in b) is separated into a third mother liquor and the intended pure substance in a separation zone, as well as to an apparatus suitable for performing said process.

Abstract: A volume reduction process comprises combinations of a freezing eutectic, bulk, indirect crystallization process and a radwaste electrodialysis process. When employed as a liquid radioactive waste management system (LWMS) for light water reactors (LWR's), this process is designed to process liquid low-level radioactive waste (LLW) and to handle the radioactive influent in nuclear power plants (NPPs) prior to release to the environment and disposal of the radioactive material present in the waste streams.

Abstract: Method for the production of anhydrous crystalline fructose in which the mass M subjected to crystallization traverses from top to bottom, continuously and with malaxation, a vessel 1 inside which it is subjected to a temperature gradient decreasing overall from top to bottom, the crystalline mass being recovered continuously at the bottom of the vessel, means being provided to take up at an intermediate level 8 a fraction of the mass M and to recycle it to a level 9 situated in the vicinity of the upper end of the vessel.

Abstract: Particulate compositions of rare earth oxides wherein the particles are present in the form of single crystals of homogeneous size and morphology, the dimensions of which are less than or equal to 10 .mu.m and greater than approximately 0.05 .mu.m and that at least 80% of the particles have dimensions varying within a range of x.+-.0.2 x, x being the mean dimension of the particles of the composition under consideration, with the understanding that the variation of the range of .+-.0.2 x is not less than .+-.0.1 .mu.m.

Abstract: A capacitance probe is used to monitor changes in the specific electrical conductivity of the synthesis mixture used to form a solid, crystalline silicate product, especially an aluminosilicate zeolite. The technique may be used to monitor the progress of zeolite crystallization without sampling the crystallization mixture and is useful in continuous crystallization operations.

Abstract: A mass constituted by glucose syrup and anhydrous dextrose crystals is led to pass through from top to bottom and with malaxation a crystallization zone 1 of axis preferably substantially vertical in which said mass is subject to a temperature gradient globally decreasing by 0.2.degree. to 2.degree. C./hour from top to bottom possibly modulated, said zone being supplied through pipe 2 with glucose syrup and through pipe 7 with mass subject to crystallization M taken up at 8 and recycled at 9.

Abstract: A method and an apparatus for growing a crystal of a compound semiconductor, in which a heater, used to heat a boat for growing the semiconductor crystal, is disposed around an ampule containing the boat, and a melt of the compound semiconductor, which is prepared in the boat, is freezed gradually at a predetermined temperature gradient including the freezing point of the melt, from a crystal growth starting end of the boat to a crystal growth terminating end thereof, whereby a single crystal or a polycrystal is grown. At the start of crystal growth, a crystalline nucleus is formed by periodically changing the temperature of the crystal growth starting end of the boat, in descending and ascending modes, within a temperature range lower than the melting point of the compound semiconductor, after once lowering the temperature of the starting end to a level lower than the melting point by means of a heater block opposed to the starting end.

Abstract: The crystallization of a crystalline silicate product from an crystallization mixture is monitored by measuring the specific electrical conductivity of the mixture. The crystallization of metallosilicates, such as aluminosilicate zeolites, may be monitored in this way. Measurement of the electrical conductivity of the crystallization mixture may be carried out on line in a batch or continuous crystallization process. In a continuous process the conductivity may be monitored and used to control the crystallization process parameters in order to achieve a desired degree of crystallinity in the product.

Abstract: An improved process for the manufacture of sodium metabisulfite is provided. In this process, the chemical reaction forming sodium bisulfite solution is carried out separately from the crystallization of sodium metabisulfite. The crystallization step is carried out without chemical alteration and without pH adjustment.

Abstract: A method for purifying silicon comprises the steps of providing a body of molten silicon-rich material in a solvent metal comprising copper or copper-aluminum combination 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 comprising copper or copper-aluminum 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 producing acidic boratozirconium chloride sols which comprises: reacting a zirconium compound with a boron compound in molar ratios of B/Zr of 0.3-1.2 together with a compound of a metal M other than boron, the metal M being selected from the group consisting of divalent, trivalent, tetravalent and pentavalent metals in molar ratios of M/Zr of about 0.01-1 in water in the presence of chloride ions in molar ratios of Cl/Zr of not less than about 1.The acidic boratozirconium chloride sol may be converted to basic boratozirconium sols by reacting the acidic sol with a basic carbonate compound such as ammonium carbonate.The sols, either acidic or basic, are readily gelled by contact with a dehydration solvent such as methanol or acetone.The gel is calcined at relatively low temperatures to provide zirconia which is either very pure or stabilized in varied degrees.

Abstract: A process for the preparation of a crystalline sheet-type alkali metal silicate is described, in which an aqueous solution of an alkali metal silicate or a suspension of an amorphous alkali metal silica having a molar ratio M.sub.2 O (unneutralized)/SiO.sub.2, where M represents an alkali metal, of 0.05:1 to 0.8:1 is allowed to react at temperatures of 70.degree. to 250.degree. C. until the sheet-type alkali metal silicate crystallizes out. After the beginning of crystallization, an acidic compound is added in an amount such that an M.sub.2 O (unneutralized)/SiO.sub.2 ratio of 0.05:1 to 0.8:1 is constantly maintained in the mother liquor of a filtered sample. However, at least an amount corresponding to 5 milliequivalents of H.sup.+ per mole of SiO.sub.2 in the alkali metal silicate used is added. The use of seed crystals of the desired sheet silicate is advantageous.

Abstract: A process is disclosed for the preparation of potassium nitrate by means of the reaction of nitric acid with potassium carbonate, wherein potassium carbonate is obtained by means of an electrochemical process.

Abstract: An improved process is described for recovering lithium from evaporatively concentrated brines. Epsom salt recovered from the brine at about 0.degree. C. is added to the concentrated lithium-containing brine, so as to precipitate lithium sulfate monohydrate, the brine having previously been subjected to the sequential steps of two stage chilling, evaporative concentration, further chilling and vacuum evaporation.

Abstract: In one embodiment of the present invention, silicon spheres are fabricated by applying a slurry of metallurgical grade silicon, or other suitable material, on the surface of a substrate capable of maintaining integrity beyond the melting point of silicon. The layer of metallurgical grade silicon is then patterned to provide regions of metallurgical grade silicon of uniform size. The substrate and metallurgical grade silicon are then heated beyond the melting point of silicon. The metallurgical grade silicon then beads to the surface as relatively pure silicon and forms silicon spheres due to the high cohesion of silicon. The structure is then cooled below the melting point of silicon and the silicon spheres then crystallize. The silicon spheres are then removed from the surface of the substrate and are further processed using techniques disclosed in copending U.S. patent application Ser. Nos. 647,551 and 647,578 to further purify the crystalline silicon spheres.

Abstract: Polymerization grade phosphonitrilic chloride trimer is made by reacting NH.sub.4 Cl and PCl.sub.5 in a solvent (e.g. monochlorobenzene) to form a crude trimer solution, filtering the solution to remove unreacted NH.sub.4 Cl, distilling a portion of the solvent to form a hot concentrate, cooling the concentrate to obtain a precipitate, distilling the precipitate at reduced pressure to first remove a forecut and then a heart-cut of polymerization grade phosphonitrilic chloride trimer.

Abstract: An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

Abstract: Apparatus comprising a freeze exchanger in which an aqueous mixture is indirectly cooled by a cooling fluid to produce an aqueous mixture containing ice; a centrifuge; a conduit for feeding an ice slurry from the freeze exchanger to the centrifuge; a heater; a conduit for feeding ice from the centrifuge to the heater to melt the ice; a water treatment apparatus; a conduit for feeding the water from the heater to the water treatment apparatus to condition the water for contact with a reverse osmosis membrane; a reverse osmosis apparatus; and a conduit for feeding the conditioned water to the reverse osmosis apparatus in which the water is purified by reverse osmosis.

Abstract: A countercurrent, cooling crystallization and purification method for a multi-component molten mixture wherein the mixture is treated by a purification system comprising one or more crystallizers (1A, 1B) each having, at the respective upper portion, a clarifying portion (10A, 10B) and a purifier (2) arranged in series to the crystallizer or crystallizers and having, at its upper portion, a clarifying portion (20), the crystallizer or crystallizers and the purifier having a temperature difference therebetween and disposed in the order of temperature. The starting mixture is fed to one of the crystallizers and subjected to crystallization there, and the resulting crystals are taken out from the bottom of the crystallizer and fed to another crystallizer or a purifier of higher temperature while the clarified liquid, i.e., mother liquor positioned at the clarifying portion of the crystallizer is led to another crystallizer of lower temperature or discharged out of the system.

Abstract: A process for the simultaneous removal of H.sub.2 S, SO.sub.2 and elemental sulfur from gaseous mixtures, comprises treating the gaseous mixture with a solvent. After the solvent becomes loaded with the components to be removed, it is regenerated and reused. In order to obtain savings in costs and energy, the sulfur is separated from the loaded solvent by lowering the temperature thereof. In this way, chemical regeneration of the scrubbing medium takes place within the cycle eliminating the requirement for outside regenerating apparatus.

Abstract: Crystals (51) of high morphological quality are grown by dissolution of a substance (28) to be grown into the crystal (51) in a suitable solvent (30) under high pressure, and by subsequent slow, time-controlled reduction of the pressure of the resulting solution (36). During the reduction of the pressure interchange of heat between the solution (36) and the environment is minimized by performing the pressure reduction either under isothermal or adiabatic conditions.

Abstract: A method of and system for removing silicon from a high temperature liquid sodium coolant system for a nuclear reactor. The sodium is cooled to a temperature below the silicon saturation temperature and retained at such reduced temperature while inducing high turbulence into the sodium flow for promoting precipitation of silicon compounds and ultimate separation of silicon compound particles from the liquid sodium.