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.

An active material recovery apparatus includes a heat treatment bath and a screening wall extending along a first axis. The heat treatment bath includes a heating zone and the screening wall includes a cooling zone. The active material recovery apparatus includes an exhaust injection and a degassing system. The heat treatment bath is configured to remove a binder and a conductive material in an active material layer and to perform heat treatment in air on an electrode scrap including the active material layer on a current collector. The screen wall is configured to recover the active material in powder form. The active material recovery apparatus is configured to separately recover the current collector that does not pass through the screening wall. The heat treatment bath includes protrusions in a sawtooth shape on a first cross-section orthogonal to the first axis.

A multitubular rotary heat exchanger has a stationary shielding unit. The shielding unit is positioned in close proximity to a tube plate outside a heating or cooling region. A stationary surface of the shielding unit is positioned in opposition to and in close proximity to an end opening of a heat transfer tube moving in an upper zone of the heating or cooling region, thereby transiently reducing or restricting the flow rate of the thermal medium fluid flowing through the heat transfer tube moving in the upper zone.

A multitubular rotary heat exchanger has a stationary shielding unit. The shielding unit is positioned in close proximity to a tube plate outside a heating or cooling region. A stationary surface of the shielding unit is positioned in opposition to and in close proximity to an end opening of a heat transfer tube moving in an upper zone of the heating or cooling region, thereby transiently reducing or restricting the flow rate of the thermal medium fluid flowing through the heat transfer tube moving in the upper zone.

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 rotary kiln for reducing phosphate ore in kiln phosphoric acid process, comprising a kiln body, a kiln head box, a kiln tail box and a driving device for driving the rotation of the kiln body, wherein a fuel burner is provided at the kiln head, a feed pipe and an outlet flue connected to an external hydration tower are provided at the kiln tail box, the upper part of the kiln body is provided with no air pipe, the outlet flue is provided in the radius range of the kiln body with the axis of the rotary kiln as a center, and the fume conveying direction in the outlet flue is substantially parallel to the axis direction of the rotary kiln or has an included angle of less than 45 thereto. The rotary kiln can effectively mitigate the phenomenon of ring forming in the kiln tail of the rotary kiln.

The production of a quartz glass grit comprises the granulation of pyrogenetically produced silicic acid, and the formation of a SiO.sub.2 granulate and the vitrification of the SiO.sub.2 granulate using a treatment gas, which contains at least 30% by volume of helium and/or hydrogen. Said process is time consuming and cost intensive. In order to provide a method which makes it possible, starting from a porous SiO.sub.2 granulate, to manufacture, in a cost effective manner, a dense, synthetic quartz glass grit, which is suitable for melting bubble-free components made of quartz glass, according to the invention the vitrification of the SiO.sub.2 granulate occurs in a rotary kiln having a mullite-containing ceramic rotary kiln, for the manufacture of which a starting powder, which contains a molar proportion of at least 45% SiO.sub.2 and Al.sub.2O.sub.3 is applied by means of a thermal powder spraying method, forming a mullite-containing layer on a mold core, and the mold core is subsequently removed, and wherein the ceramic rotary kiln is flooded with a treatment gas or rinsed with a treatment gas, and wherein the ceramic rotary kiln is flooded with a treatment gas or rinsed with a treatment gas, which contains at least 30% by volume of helium and/or hydrogen.

The production of a quartz glass grit comprises the granulation of pyrogenetically produced silicic acid, and the formation of a SiO.sub.2 granulate and the vitrification of the SiO.sub.2 granulate using a treatment gas, which contains at least 30% by volume of helium and/or hydrogen. Said process is time consuming and cost intensive. In order to provide a method which makes it possible, starting from a porous SiO.sub.2 granulate, to manufacture, in a cost effective manner, a dense, synthetic quartz glass grit, which is suitable for melting bubble-free components made of quartz glass, according to the invention the vitrification of the SiO.sub.2 granulate occurs in a rotary kiln having a mullite-containing ceramic rotary kiln, for the manufacture of which a starting powder, which contains a molar proportion of at least 45% SiO.sub.2 and Al.sub.2O.sub.3 is applied by means of a thermal powder spraying method, forming a mullite-containing layer on a mold core, and the mold core is subsequently removed, and wherein the ceramic rotary kiln is flooded with a treatment gas or rinsed with a treatment gas, and wherein the ceramic rotary kiln is flooded with a treatment gas or rinsed with a treatment gas, which contains at least 30% by volume of helium and/or hydrogen.