Process for the manufacture of a material on the basis of calcium- and/or magnesium carbonate having a reduced decrepitation tendency, wherein a material on the basis of calcium- and/or magnesium carbonate is treated with at least one additive selected among alkali metal compounds and/or acids and/or alkaline earth metal compounds in an amount of 0.05 to 5 wt. % based on the amount of the material on the basis of calcium- and/or magnesium carbonate. Also claimed are the material obtainable by the process and showing reduced decrepitation tendency and the use of such material in the manufacture of glass.

A process for forming granulated slag includes collecting a molten slag flow directly from a blast furnace in a temperature range between 2500 F. and 2600 F., quenching the molten slag flow with a flowing spray of water while the molten slag flow is still in the temperature range between 2500 F. and 2600 F. to create a granulated slag flow such that ferrous materials and non-ferrous metallic materials solidify joined together in the granulated slag flow, drying the granulated slag flow, magnetically separating the solidified joined ferrous materials and non-ferrous metallic materials from the granulated slag with a magnet device, and size-screening the granulated slag flow.

In a method of manufacturing porous glass base for optical fiber, a liquid organic siloxane raw material stored in a raw material tank of internal pressure P1 is controlled by a mass flow controller at a predetermined flow rate and pumped through pipe of internal pressure P2 to a vaporizer, the liquid raw material is vaporized in the vaporizer and supplied as a gas raw material to a burner, and the silica fine particles formed by burning the gas raw material in the burner are deposited to form a porous glass base material, where P1?P2 is satisfied.

One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate, making a glass melt out of the silicon dioxide granulate, and making a quartz glass body out of at least a part of the glass melt. In one aspect, providing a silicon dioxide granulate includes providing of a silicon dioxide powder and processing of the powder to obtain a silicon dioxide granulate including the spray drying of a silicon dioxide slurry using a nozzle. The nozzle has a contact surface to the slurry made of glass, plastic or a combination thereof. Furthermore, one aspect relates to a quartz glass body obtainable by this process. Furthermore, one aspect relates to the preparation of a silicon dioxide granulate. One aspect also relates to a light guide, an illuminant, and a formed body, made from processing of the quartz glass body.

One aspect relates to a light guide comprising a jacket and one or more cores, wherein the jacket surrounds the cores. Each core has a refractive index profile perpendicular to the maximum extension of the core, wherein at least one refractive index n.sub.K of each refractive index profile is greater than the refractive index n.sub.M1 of the jacket. The jacket is made of silicon dioxide and has an OH content of less than 10 ppm, a chlorine content of less than 60 ppm, and an aluminium content of less than 200 ppb. One aspect also relates to a silicon dioxide granulate I, characterized by a chlorine content of less than 200 ppm and an aluminium content of less than 200 ppb, in each case based on the total weight of the silicon dioxide granulate I.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate obtainable from a silicon dioxide powder, wherein the silicon dioxide granulate has a larger particle size than the silicon dioxide powder, ii.) Making a glass melt out of silicon dioxide granulate and iii.) Making a quartz glass body out of at least part of the glass melt, wherein the melting crucible has at least one inlet and at least one outlet, wherein at least part of the glass melt is removed via the melting crucible outlet. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, wherein the silicon dioxide granulate was made from pyrogenic silicon dioxide powder and the silicon dioxide granulate has a BET surface area in a range from 20 to 40 m.sup.2/g, ii.) Making a glass melt out of silicon dioxide granulate in an oven and iii.) Making a quartz glass body out of at least part of the glass melt, wherein the oven has at least a first and a further chamber connected to one another via a passage, wherein the temperature in the first chamber is lower than the temperature in the further chambers. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

The invention relates to a process for the preparation of a quartz glass body comprising the process steps i.) Providing a silicon dioxide granulate, ii.) Making a glass melt out of silicon dioxide granulate in an oven and iii.) Making a quartz glass body out of at least part of the glass melt, wherein the oven comprises a standing sinter crucible. The invention further relates to a quartz glass body which is obtainable by this process. The invention further relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

To provide granules for the production of silicate glass, said granules being less likely to adhere even if heated at a high temperature exceeding 800 C. A method for producing granules, which has a step of mixing a glass raw material composition composed essentially of an alkali metal source, an alkaline earth metal source and a powdery silicon source, with water, followed by compression molding, and which is characterized in that the glass raw material composition contains at least 50 mass % of the silicon source, and at least 10 mass % in total of the alkali metal source and the alkaline earth metal source, as calculated as oxides, based on 100 mass % of the silicate glass obtainable from the granules, the alkali metal source contains an alkali metal carbonate, and D90 representing the particle size at a cumulative volume of 90% in the particle size accumulation curve of the alkaline earth metal source is at most 100 m.

In order to well perform recoating regardless of the type of granular material and reuse a refractory aggregate in an unprinted portion without any regeneration process in the manufacture of a three-dimensional lamination-shaped mold, this invention provides a granular material for use in shaping a three-dimensional laminated mold, which is coated with an acid as a catalyst which activates and cures an organic binder for binding the granular material. The acid contains at least one of sulfuric acid, phosphoric acid, a sulfonic acid and a carboxylic acid, and is one of a mixture of sulfuric acid and another acid, phosphoric acid only, a mixture of phosphoric acid and another acid, sulfonic acid only, a mixture of sulfonic acid and another acid and a mixture of a carboxylic acid and another acid.