Abstract: The invention relates to a reducing agent for the soluble chromate content of cement and to methods for the production thereof, which comprise concentrating an used sulfuric acid, containing iron (II) sulfate, and separating the sulfuric acid from the obtained precipitate which contains iron (II) sulfate.

Abstract: A composition containing titanium and iron compounds, in particular decomposition residue that accumulates as a production residue after the sulphate process during the production of titanium dioxide, is used as an adsorbing agent for inorganic and organic compounds, for example compounds containing phosphorus, arsenic, antimony, sulphur, selenium, tellurium, the cyano group or heavy metal. Toxic substances and pollutants may be removed from a fluid using the adsorbing agent.

Abstract: A composition containing titanium and iron compounds, in particular decomposition residue that accumulates as a production residue after the sulphate process during the production of titanium dioxide, is used as an adsorbing agent for inorganic and organic compounds, for example compounds containing phosphorus, arsenic, antimony, sulphur, selenium, tellurium, the cyano group or heavy metal. Toxic substances and pollutants may be removed from a fluid using the adsorbing agent.

Abstract: The invention relates to a reducing agent for the soluble chromate content of cement and to methods for the production thereof, which comprise concentrating an used sulfuric acid, containing iron (II) sulfate, and separating the sulfuric acid from the obtained precipitate which contains iron (II) sulfate.

Abstract: The invention relates to fine-particled alkaline-earth titanates and to a method for the production thereof by reacting alkaline-earth metal compounds with titanium dioxide particles. The titanium dioxide particles have a BET-surface greater than 50 m2/g. The titanium dioxide particles can have a very low sulphate, chloride and carbon content. The reaction can take place at a temperature below 700° C. The alkaline-earth titanate can have a BET-surface of 5-100 m2/g. Advantageously, it does not contain any hydroxyl groups in the crystal lattice. The alkaline-earth titanate can be used in the production of microelectronic components.

Abstract: The invention relates to fine-particled alkaline-earth titanates and to a method for the production thereof by reacting alkaline-earth metal compounds with titanium dioxide particles. The titanium dioxide particles have a BET-surface greater than 50 m2/g. The titanium dioxide particles can have a very low sulphate, chloride and carbon content. The reaction can take place at a temperature below 700° C. The alkaline-earth titanate can have a BET-surface of 5-100 m2/g. Advantageously, it does not contain any hydroxyl groups in the crystal lattice. The alkaline-earth titanate can be used in the production of microelectronic components.

Abstract: The invention relates to a reducing agent for the soluble chromate content of cement and to methods for the production thereof, which comprise concentrating an used sulfuric acid, containing iron(II) sulfate, and separating the sulfuric acid from the obtained precipitate which contains iron(II) sulfate.

Abstract: The invention relates to a method for directly cooling fine-particle, powdery solid substances by using a cooling medium provided in the form of low-boiling condensed gases or of cold gases obtained therefrom, whereupon bulk material packings are subsequently filled with these solid substances. The invention also relates to a device for directly cooling the fine-particle, powdery solid substances and to fine-particle, powdery solid substances, which are located inside bulk material packings and which, compared to air, have a lower oxygen content in the gas phase between the solid substance particles.

Abstract: The invention relates to a method for directly cooling fine-particle, powdery solid substances by using a cooling medium provided in the form of low-boiling condensed gases or of cold gases obtained therefrom, whereupon bulk material packings are subsequently filled with these solid substances. The invention also relates to a device for directly cooling the fine-particle, powdery solid substances and to fine-particle, powdery solid substances, which are located inside bulk material packings and which, compared to air, have a lower oxygen content in the gas phase between the solid substance particles.

Abstract: Process for the preparation of iron oxide pigments from the waste acid resulting from the preparation of titanium dioxide by the sulfate process, characterized in that in a first stage a partial neutralization of the sulfuric acid contained in the waste acid is performed with compounds from the group comprising metallic iron and/or iron compounds, the sulfuric acid is optionally further neutralized with a further alkaline compound, the precipitate containing Ti, Al, Cr and V compounds is separated from the resultant reaction product and an iron oxide yellow pigment or iron oxide black pigment is precipitated from the resultant iron sulfate-containing solution by addition of alkaline compounds as well as an oxidizing agent, each pigment being able to be baked to form an iron oxide red pigment.

Abstract: Process for the production of gypsum and also of an iron-oxide pigment from the waste acid that accumulates in the course of the production of titanium dioxide in accordance with the sulfate process, characterized in that in a first stage a partial neutralization of the waste acid is effected with a calcium compound subject to precipitation and optionally direct separation of gypsum, subsequently the remaining solution is neutralized further in a second stage subject to precipitation of a deposit containing Ti, Al, Cr, V and optionally Fe(III) and from the solution containing iron sulfate that is obtained after separation of the solids an iron-oxide pigment is produced in a third stage by addition of alkaline compounds and also of an oxidizing agent.

Abstract: Process for the production of gypsum and also of an iron-oxide pigment from the waste acid that accumulates in the course of the production of titanium dioxide in accordance with the sulfate process, characterized in that in a first stage a partial neutralization of the waste acid is effected with a calcium compound subject to precipitation and optionally direct separation of gypsum, subsequently the remaining solution is neutralized further in a second stage subject to precipitation of a deposit containing Ti, Al, Cr, V and optionally Fe(III) and from the solution containing iron sulfate that is obtained after separation of the solids an iron-oxide pigment is produced in a third stage by addition of alkaline compounds and also optionally addition of ammonia and also of an oxidizing agent, ammonia being liberated by addition of CaO and/or Ca(OH)2 from the solution containing (NH4)2SO4 that is obtained after separation of the iron-oxide pigment.