A Portland cement production (PCP) process is conjoined with a waste-to-energy (WTE) process using refuse-derived fuels (RDFs). Both processes operate simultaneously to reduce harmful compounds being discharged into the environment. The PCP and WTE processes are conjoined by borrowing a minor portion of pre-heated comminuted limestone from a PCP process feedstream and diverting it to the WTE process. Some of the pre-heated comminuted limestone is converted to CaO. The calcium compounds from the pre-heated comminuted limestone act as a fluxing agents and sorbents to bind with and remove undesired impurities, such as elemental particulate matter, excess CO.sub.2 and acid gasses associated with sulfur and chlorine that are released during the pyrolization of RDFs. The ash, char waste and reacted calcium compounds from the pyrolization process can be comingled and returned to the PCP process as a secondary cement meal feedstock.

A Portland cement production (PCP) process is conjoined with a waste-to-energy (WTE) process using refuse-derived fuels (RDFs). Both processes operate simultaneously to reduce harmful compounds being discharged into the environment. The PCP and WTE processes are conjoined by borrowing a minor portion of pre-heated comminuted limestone from a PCP process feedstream and diverting it to the WTE process. Some of the pre-heated comminuted limestone is converted to CaO. The calcium compounds from the pre-heated comminuted limestone act as a fluxing agents and sorbents to bind with and remove undesired impurities, such as elemental particulate matter, excess CO.sub.2 and acid gasses associated with sulfur and chlorine that are released during the pyrolization of RDFs. The ash, char waste and reacted calcium compounds from the pyrolization process can be comingled and returned to the PCP process as a secondary cement meal feedstock.

In production of a reactive metal using a melting furnace for producing metal having a hearth, ingots can be efficiently produced by efficiently cooling the ingots extracted from the mold provided in the melting furnace. In addition, an apparatus structure in which multiple ingots can be produced with high efficiency and high quality from one hearth, is provided. A melting furnace for producing metal is provided, the furnace has a hearth for having molten metal formed by melting raw material, a mold in which the molten metal is poured, an extracting jig which is provided below the mold for extracting ingot cooled and solidified downwardly, a cooling member for cooling the ingot extracted downwardly of the mold, and an outer case for keeping the hearth, the mold, the extracting jig, and the cooling member separated from the air, wherein at least one mold and extracting jig are provided in the outer case, and the cooling member is provided between the outer case and the ingot, or between the multiple ingots.

The invention relates to a process plant (20) for converting a solid input material into a solid process product. The process plant (20) includes a calciner which is connected to a heat exchanger (26) and to which the input material can be continuously supplied for heating in order to transform the input material into an intermediate product. In the process plant (20) there is a kiln for converting the intermediate product into the process product by means of thermal treatment, raw gas being produced in doing so. The process plant (20) has a raw gas line system (50) comprising a raw gas line (50.1) which extends from the kiln to the calciner and through which the raw gas can flow from the kiln into the calciner for transferring raw gas heat to the input material, and includes a cooling device for cooling the process product after the thermal treatment in the kiln by transferring heat from the process product to a cooling gas containing oxygen, as a result of which a hot gas containing oxygen is generated. According to the invention, in the process plant (20) there is a waste air purification device for oxidizing raw gas, which is connected to the calciner via a raw gas line system (50), wherein a hot gas line system which is used for supplying hot gas generated from the cooling device is attached to the raw gas line system (50). The invention also relates to a method for converting a solid input material into a solid process product and to a method for purifying raw gas produced during the manufacture of cement.

The invention relates to a process plant (20) for converting a solid input material into a solid process product. The process plant (20) includes a calciner which is connected to a heat exchanger (26) and to which the input material can be continuously supplied for heating in order to transform the input material into an intermediate product. In the process plant (20) there is a kiln for converting the intermediate product into the process product by means of thermal treatment, raw gas being produced in doing so. The process plant (20) has a raw gas line system (50) comprising a raw gas line (50.1) which extends from the kiln to the calciner and through which the raw gas can flow from the kiln into the calciner for transferring raw gas heat to the input material, and includes a cooling device for cooling the process product after the thermal treatment in the kiln by transferring heat from the process product to a cooling gas containing oxygen, as a result of which a hot gas containing oxygen is generated. According to the invention, in the process plant (20) there is a waste air purification device for oxidizing raw gas, which is connected to the calciner via a raw gas line system (50), wherein a hot gas line system which is used for supplying hot gas generated from the cooling device is attached to the raw gas line system (50). The invention also relates to a method for converting a solid input material into a solid process product and to a method for purifying raw gas produced during the manufacture of cement.

The invention relates to a cooling system (3) for rotary furnaces (1), and also to a method for operating such a cooling system (3). The cooling system (3) comprises for this purpose an arrangement of one or more cooling modules (31, 31, 31), which are arranged in the portion (21) to be cooled of the furnace shell (2), at least along the axis of rotation (R) of the furnace shell (2), wherein each cooling module (31) comprises an activatable switching valve (311) and a fan nozzle (312) for issuing a pulsed fan-shaped cooling liquid jet (4) and, when there are a number of cooling modules, the neighbouring cooling modules (31, 31, 31) are arranged in relation to one another at a distance (A1) parallel to the axis of rotation (R) of the furnace shell (2). Each cooling module (31, 31, 31) comprises at least one first heat sensor (313), connected to a cooling system control (32), for measuring a first local temperature (T1) of the furnace shell (2) ahead of the area of impingement (41) as seen in the direction of rotation (DR) of the furnace shell (2).

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.

A pelletizing process, having two distinct serial stages. In the first stage, crude (or green) pellets of a given ore, or a mixture of ores (such as iron ore, manganese ore and other minerals), are produced, while in the second stage, a Device for Improvement of Crude Pellets, is used. The Device includes a slightly elastic and smooth surface, with reduced attrition rate, that may be striated, and that, encircled in itself, forms a cylindrical geometric hollow figure supported by a metallic structure, also cylindrical, with the set forming a finishing drum. The Device rotates with an inner and continuous charge of ore pellets, and can rearrange the structure of such pellets, improving their physical quality: compressive strength, sphericity and surface finishing, and assimilate fines generated during previous processes. This device allows application of diverse materials to the pellets to add required extra properties per specificities of subsequent industrial processes.

A pelletizing process, having two distinct serial stages. In the first stage, crude (or green) pellets of a given ore, or a mixture of ores (such as iron ore, manganese ore and other minerals), are produced, while in the second stage, a Device for Improvement of Crude Pellets, is used. The Device includes a slightly elastic and smooth surface, with reduced attrition rate, that may be striated, and that, encircled in itself, forms a cylindrical geometric hollow figure supported by a metallic structure, also cylindrical, with the set forming a finishing drum. The Device rotates with an inner and continuous charge of ore pellets, and can rearrange the structure of such pellets, improving their physical quality: compressive strength, sphericity and surface finishing, and assimilate fines generated during previous processes. This device allows application of diverse materials to the pellets to add required extra properties per specificities of subsequent industrial processes.