The present disclosure is related to the field of steel slag treatment, and in particular to a process for stabilizing steel slag, the process comprising subjecting the steel slag to an autoclave treatment by use of a high temperature and pressure saturated vapor at a pressure of 2.0 MPa or above. The process provides the slag with reliable volume stability and makes it possible to meet desired requirements of various building materials. Additionally, the process is low cost, non-polluting, and of very high industrial value.

The present disclosure is related to the field of steel slag treatment, and in particular to a process for stabilizing steel slag, the process comprising subjecting the steel slag to an autoclave treatment by use of a high temperature and pressure saturated vapor at a pressure of 2.0 MPa or above. The process provides the slag with reliable volume stability and makes it possible to meet desired requirements of various building materials. Additionally, the process is low cost, non-polluting, and of very high industrial value.

An installation for thermal treatment of free-floating raw material, in particular cement raw meal and/or mineral products, may include a riser line through which hot gases can flow. The riser line has at least one fuel inlet for introducing fuel into the riser line. The riser line has at least one raw meal inlet for introducing raw meal into the riser line, which raw meal inlet is arranged upstream of the fuel inlet in a flow direction of gas inside the riser line. Further, a method for thermal treatment of free-floating raw material may involve introducing fuel via a fuel inlet into a riser line for guiding hot gases and introducing raw meal into the riser line. The raw meal is introduced into the riser line upstream of the fuel inlet in the flow direction.

An installation for thermal treatment of free-floating raw material, in particular cement raw meal and/or mineral products, may include a riser line through which hot gases can flow. The riser line has at least one fuel inlet for introducing fuel into the riser line. The riser line has at least one raw meal inlet for introducing raw meal into the riser line, which raw meal inlet is arranged upstream of the fuel inlet in a flow direction of gas inside the riser line. Further, a method for thermal treatment of free-floating raw material may involve introducing fuel via a fuel inlet into a riser line for guiding hot gases and introducing raw meal into the riser line. The raw meal is introduced into the riser line upstream of the fuel inlet in the flow direction.

A method for using waste heat from a cement producing plant, wherein heat of a process gas is used through a heat exchanger, which comprises a sequence of cyclones, for heating raw mix. A cement producing plant having at least one calcinator and at least one heat exchanger, which comprises a series of cyclones for heating raw mix. The process gas is removed at the outlet of the calcinator and/or at the gas-side outlet of the first cyclone in the heat exchanger in the direction of gas flow and, once the heat has been removed in a steam vessel, the cooled process gas is fed back into the second cyclone or third cyclone in the heat exchanger in the direction of gas flow. The heat taken from the process can be used for the further heating of unrecovered heat which can thereby be more efficiently converted into electrical energy.

The disclosure discloses a production method for producing cement and co-producing sulfuric acid from phosphogypsum. The method includes: pretreating and purifying the phosphogypsum to reduce insoluble phosphorus, water-soluble phosphorus impurities, and most free water in the phosphogypsum, directly feeding the materials kneaded and granulated with a reducing agent into a reduction and decomposition integrated rotary kiln with a fluidized preheating function, and controlling to carry out step-by-step heating, drying, dehydration, reduction and decomposition in a gas phase atmosphere under pulverized coal combustion; using sulfur dioxide gas generated after reduction and decomposition to produce the sulfuric acid after dust removal and purification; making the materials after reduction and decomposition enter an oxidation calcining kiln for sintering a cement clinker, and controlling to heat, mineralize and sinter the cement clinker in the gas phase atmosphere under the pulverized coal combustion.

The disclosure discloses a production method for producing cement and co-producing sulfuric acid from phosphogypsum. The method includes: pretreating and purifying the phosphogypsum to reduce insoluble phosphorus, water-soluble phosphorus impurities, and most free water in the phosphogypsum, directly feeding the materials kneaded and granulated with a reducing agent into a reduction and decomposition integrated rotary kiln with a fluidized preheating function, and controlling to carry out step-by-step heating, drying, dehydration, reduction and decomposition in a gas phase atmosphere under pulverized coal combustion; using sulfur dioxide gas generated after reduction and decomposition to produce the sulfuric acid after dust removal and purification; making the materials after reduction and decomposition enter an oxidation calcining kiln for sintering a cement clinker, and controlling to heat, mineralize and sinter the cement clinker in the gas phase atmosphere under the pulverized coal combustion.

Portland cement clinker that includes C.sub.3A and C.sub.4AF in total from 22 to 40 mass % calculated by Bogue's formulas and has an iron modulus (I.M.) of 0.8 to 1.3 is produced. The burned raw materials are annealed at a cooling rate of 20 degree Celsius or lower at least to 1200 degree Celsius so that the lightness of the cement clinker is made high. When annealing till lower temperatures, the lightness value becomes generally higher, but the effect becomes negligible lower at 1000 degree Celsius. Therefore, the raw materials are quenched at 1000 degree Celsius and lower for improving the productiveness.

Portland cement clinker that includes C.sub.3A and C.sub.4AF in total from 22 to 40 mass % calculated by Bogue's formulas and has an iron modulus (I.M.) of 0.8 to 1.3 is produced. The burned raw materials are annealed at a cooling rate of 20 degree Celsius or lower at least to 1200 degree Celsius so that the lightness of the cement clinker is made high. When annealing till lower temperatures, the lightness value becomes generally higher, but the effect becomes negligible lower at 1000 degree Celsius. Therefore, the raw materials are quenched at 1000 degree Celsius and lower for improving the productiveness.

The present invention discloses a cooler for cooling particulate material which has been subjected to heat treatment in an industrial kiln, such as a rotary kiln for manufacturing cement clinker. This cooler comprises an inlet, an outlet, end wall, side walls, a bottom and a ceiling, at least three reciprocating supporting lanes for receiving, supporting and transporting the material to be cooled, the lanes are moving following the walking floor principles as well as means for injecting cooling gas into the material through grate plates in the lanes. With the present invention it is an aim to have an increase in the vertical shearing height, and still having stationary clinker on top of the grate plates.