A hood for a taphole and a tapping spout in a submerged arc furnace in the production of silicon. The hood has at least two suction ducts which are placed asymmetrically on either side of the hood, and is useful in a process for the production of silicon in a submerged arc furnace, wherein liquid silicon and refining gas escape from a taphole of a crucible, wherein the liquid silicon flows on a tapping spout into a ladle, wherein the refining gas is sucked in a hood which has at least two suction ducts which are placed on either side of the hood.

Systems, methods and compositions to produce fine powders are described. These include forming a hypereutectic melt including a target material, a sacrificial-matrix material, and an impurity, rapidly cooling the hypereutectic melt to form a hypereutectic alloy having a first phase and a second phase, annealing the hypereutectic alloy to alter a morphology of the target material to thereby produce target particles, and removing the sacrificial matrix to thereby produce a fine powder of the target particles. The first phase is defined by the target material and the second phase is defined by the sacrificial-matrix material. The sacrificial-matrix material forms a sacrificial matrix having the target material dispersed therethrough.

Systems, methods and compositions to produce fine powders are described. These include forming a hypereutectic melt including a target material, a sacrificial-matrix material, and an impurity, rapidly cooling the hypereutectic melt to form a hypereutectic alloy having a first phase and a second phase, annealing the hypereutectic alloy to alter a morphology of the target material to thereby produce target particles, and removing the sacrificial matrix to thereby produce a fine powder of the target particles. The first phase is defined by the target material and the second phase is defined by the sacrificial-matrix material. The sacrificial-matrix material forms a sacrificial matrix having the target material dispersed therethrough.

In a known method for treating pourable, inorganic grain, a heated rotary tube is used that rotates about an axis of rotation and surrounds a treatment chamber that is divided into a plurality of treatment zones by means of separating elements. The grain is supplied to the treatment chamber at a grain inlet side and is transported, in a grain transport direction, to a grain outlet side and is exposed to a treatment gas in the process. In order, proceeding herefrom, to allow for reliable and reproducible thermal treatment of pourable inorganic grain, in particular SiO.sub.2 grain in the rotary kiln, in a manner having low and effective consumption of treatment gas, it is proposed for spent treatment gas to be suctioned out of a reaction zone of the treatment chamber, by a gas manifold that rotates about the longitudinal axis thereof.

In a known method for treating pourable, inorganic grain, a heated rotary tube is used that rotates about an axis of rotation and surrounds a treatment chamber that is divided into a plurality of treatment zones by means of separating elements. The grain is supplied to the treatment chamber at a grain inlet side and is transported, in a grain transport direction, to a grain outlet side and is exposed to a treatment gas in the process. In order, proceeding herefrom, to allow for reliable and reproducible thermal treatment of pourable inorganic grain, in particular SiO.sub.2 grain in the rotary kiln, in a manner having low and effective consumption of treatment gas, it is proposed for spent treatment gas to be suctioned out of a reaction zone of the treatment chamber, by a gas manifold that rotates about the longitudinal axis thereof.

A system and a method for producing silicon from a SiO.sub.2-containing material that includes solid SiO.sub.2. The method uses a reaction vessel including a first section and a second section in fluid communication with said first section. The method includes: heating the SiO.sub.2-containing material that includes the solid SiO.sub.2 to a SiO.sub.2-containing material that includes liquid SiO.sub.2, at a sufficient temperature to convert the solid SiO.sub.2 into the liquid SiO.sub.2; converting, in the first section, the liquid SiO.sub.2 into gaseous SiO.sub.2 that flows to the second section by reducing the pressure in the reaction vessel to a subatmospheric pressure; and reducing, in the second section, the gaseous SiO.sub.2 into liquid silicon using a reducing gas. The reducing of the pressure is performed over a continuous range of interim pressure(s) sufficient to evaporate contaminants from the SiO.sub.2-containing material, and removing by vacuum, the one or more evaporated gaseous contaminants.

A method for manufacturing polycrystalline silicon fragments includes producing a polycrystalline silicon rod by the Siemens method; crushing the polycrystalline silicon rod to obtain polycrystalline silicon fragments; and cleaning by etching the polycrystalline silicon fragments in a cleaning tank. In the cleaning, small pieces of the polycrystalline silicon having controlled shapes and sizes are present in the cleaning tank and the weight change of the small pieces of the polycrystalline silicon before and after the etching is measured to thereby manage the cleaning.

The present invention provides a method of purifying aluminum, and/or use of the purified aluminum as a solvent metal to purify silicon.

The present invention provides a method of purifying aluminum, and/or use of the purified aluminum as a solvent metal to purify silicon.

The present invention discloses a preparation method of ant nest like porous silicon for a lithium-ion battery, comprising: (1) enabling a magnesium silicide raw material to react for 2-24 h in an atmosphere containing ammonia gas at 600-900 DEG C. so as to obtain a crude product containing porous silicon (3Mg.sub.2Si+4NH.sub.3.fwdarw.3Si+2Mg.sub.3N.sub.2+6H.sub.2); the magnesium silicide raw material has a particle size of 0.2-10 m; and (2) subjecting the crude product containing porous silicon obtained in the step (1) to acid pickling so as to obtain ant nest like porous silicon for a lithium-ion battery. By improving the overall process flow of the porous silicon key preparation method as well as parameters and conditions of respective reaction steps, compared with the prior art, the preparation method has the advantage of simplicity and easiness, a large amount of porous micron silicon can be obtained by directly heating the obtained magnesium silicide in ammonia gas (or a mixed gas of ammonia gas and inert gas), and the yield is high.