The invention relates to a method for the expansion of sand grain-shaped raw material (1) in which the raw material (1) drops downwards through a substantially vertical heated shaft (4) provided with means (2) for forming a temperature profile (3), in which a shaft flow (5) prevails wherein the raw material (1) expands as a result of heat transfer in the shaft (4) to form expanded granulate (6) and the granulate formed (6) is passed into a pneumatic conveying line (7) with a conveying flow (8) for further transport.

In order to continuously check the quality of the expansion process, the bulk density of the expanded granulate (6) is measured continuously, wherein upon detecting a deviation from at least one defined bulk density, the temperature profile (3) in the shaft (4) is adapted automatically or manually and/or the feeding of raw material (1) into the shaft (4) is reduced automatically or manually.

The invention relates to a method for the expansion of sand grain-shaped raw material (1) in which the raw material (1) drops downwards through a substantially vertical heated shaft (4) provided with means (2) for forming a temperature profile (3), in which a shaft flow (5) prevails wherein the raw material (1) expands as a result of heat transfer in the shaft (4) to form expanded granulate (6) and the granulate formed (6) is passed into a pneumatic conveying line (7) with a conveying flow (8) for further transport.

In order to continuously check the quality of the expansion process, the bulk density of the expanded granulate (6) is measured continuously, wherein upon detecting a deviation from at least one defined bulk density, the temperature profile (3) in the shaft (4) is adapted automatically or manually and/or the feeding of raw material (1) into the shaft (4) is reduced automatically or manually.

An apparatus for producing a bloated mineral granulate with a heated processing channel (1) for the mineral granulate fed to a conveying flow (13), wherein an inflow opening (4) is provided in the processing channel (1) for forming a granulate-free laminar flow (5) running along the inner wall of the processing channel, is described. In order to design a device of the type described above in such a way that a continuous, qualitatively controllable production process is achieved, it is proposed in that the processing channel (1) comprises two channel sections (16), (17) with differing cross-sections, wherein the channel section (16) with a smaller cross-section projects into the channel section (17) with a larger cross-section, forming the inflow opening (4), and wherein the channel section (16) with a smaller cross-section is enclosed by the channel section (17) with a larger cross-section in such a way that an inflow opening (4) is formed completely around the projecting region of the channel section (16) with a smaller cross-section.

A method and system for expanding sand grain-shaped raw material drops raw material downwards through a substantially vertical heated shaft equipped for forming a temperature profile, in which a shaft flow prevails wherein raw material expands as a result of heat transfer in the shaft to form expanded granulate, and the granulate formed is passed into a pneumatic conveying line with a conveying flow for further transport. The method and system continuously measure the bulk density of the expanded granulate to continuously check the quality of the expansion process, automatically or manually adapting the temperature profile in the shaft and/or automatically or manually reducing the feeding of raw material into the shaft upon detecting a deviation from at least one defined bulk density.

A method and system for expanding sand grain-shaped raw material drops raw material downwards through a substantially vertical heated shaft equipped for forming a temperature profile, in which a shaft flow prevails wherein raw material expands as a result of heat transfer in the shaft to form expanded granulate, and the granulate formed is passed into a pneumatic conveying line with a conveying flow for further transport. The method and system continuously measure the bulk density of the expanded granulate to continuously check the quality of the expansion process, automatically or manually adapting the temperature profile in the shaft and/or automatically or manually reducing the feeding of raw material into the shaft upon detecting a deviation from at least one defined bulk density.

The invention relates to an apparatus (10) for producing an expanded granulate from sand-grain-shaped material (1), comprising a furnace (2) with a substantially vertically extending furnace shaft (3) and a feed device (5) arranged above or in the upper region of the furnace shaft (3) for feeding the sand-grain-shaped material (1) to the furnace shaft (3). In order to achieve uniform expansion of the sand-grain-shaped material, the feed device (8) is formed to introduce the sand-grain-shaped material (1) in form of at least one downwardly falling curtain into the upper region of the furnace shaft (3), wherein the drop section (4) of the curtain (25) lies in a decentralised, preferably peripheral region of the furnace shaft cross-section. The invention also relates to a method for producing an expanded granulate from sand-grain-shaped mineral material.

An arrangement for producing a bulk material consisting substantially of foamed or blown mineral or oxide particles by thermal treatment of a bulk material of basic particles. The arrangement includes NIR halogen radiators for generating a NIR radiation field of radiation with an active component in a near infrared, NIR, range having a wavelength in a range between 0.8 ?m and 1.5 ?m and which has a power density of at least 50 kW/m.sup.2 for thermally treating the basic particles, a conveying device for transporting a layer or stream of the bed of basic particles through the radiation field, and a controller that controls heating of the bed of basic particles such that a maximum temperature in the layer or stream is in a temperature range between 600 and 1500? C.

The present disclosure concerns expandable silica particles having a coating comprising talc powder and kaolin powder provided on the outer surface of the expandable silica particle and expandable and expanded silica particles comprising silica fume and/or ultrafine quartz silica sand beneath the surface of the particles. Methods for producing expandable and expanded silica particles are disclosed, including a method using a vibration plate and a furnace having a vibration plate for carrying out that method. The expanded silica particles have high compressive strength, substantially uniform cell size and distribution, low water absorption, and low porosity on the outer surface. They are useful as a filler in matrix materials, like concrete or epoxy, as insulation material with various binder materials, and as water filtration medium.

The present disclosure concerns expandable silica particles having a coating comprising talc powder and kaolin powder provided on the outer surface of the expandable silica particle and expandable and expanded silica particles comprising silica fume and/or ultrafine quartz silica sand beneath the surface of the particles. Methods for producing expandable and expanded silica particles are disclosed, including a method using a vibration plate and a furnace having a vibration plate for carrying out that method. The expanded silica particles have high compressive strength, substantially uniform cell size and distribution, low water absorption, and low porosity on the outer surface. They are useful as a filler in matrix materials, like concrete or epoxy, as insulation material with various binder materials, and as water filtration medium.

The invention relates to a method for producing an expanded granulate (29) made of a sand grain-shaped mineral material (1) using a propellant; wherein the material (1) is fed to a substantially upright furnace (2); wherein the material (1) is conveyed along a conveying path (4) through a plurality of vertically separated healing zones (5) in a furnace shaft (3) of the furnace (2), wherein each heating zone (5) can be heated by at least one independently controllable heating element (6); wherein the material (1) is heated to a critical temperature at which the surfaces (7) of the sand grains (1) become plastic and the sand grains (1) are expanded through the propellant. It is provided according to the invention that the material (1) is fed together with an amount of air from below, wherein the material (1) is conveyed from bottom to top along the conveying path (4) by means of the amount of air which flows from bottom to top within the furnace shaft (3) and forms an air flow (14), and wherein the expanding of the sand grains (1) occurs in the upper half, preferably in the uppermost third, of the conveying path (4).