CS260434B1 - A method for producing cement clinker from liquid or solid chlorinated organic wastes - Google Patents

Abstract

The purpose of the solution is to produce high-quality cement clinker from organic chlorine-containing waste with energy potential and their simultaneous disposal in an environmentally friendly and economically advantageous manner. The stated purpose is achieved: By dosing liquid organic waste containing chlorine together with primary noble liquid or gaseous fuel into the burner of a rotary kiln for clinker firing, whereby the resulting chlorine-containing gaseous combustion products react with alkaline components of the cement raw material to form an alkali chloride melt leading to low-temperature salt technology for the production of high-quality alinitic clinker containing calcium chlorosilicate and chloroaluminate as the main hydraulic minerals. By burning solid organic waste containing chlorine under reducing conditions in an incinerator, whereby a mixture of hydrogen chloride and energy-rich gas is fed in a secondary air stream into the rotary kiln with the same effect on clinker formation as in the case of dosing liquid waste.

Description

The solution relates to a method of producing cement clinker from liquid net solid chlorinated organic waste while simultaneously reducing the temperature/firing, while ensuring environmentally friendly disposal of the used waste.

The methods known so far for the safe disposal of chlorinated hydrocarbons, for example, especially polychlorinated biphenyls, are both investment and operationally demanding. Among other methods, there is a method of adding the above-mentioned compounds to the fuel dosed into the burners of cement rotary kilns, usually in a small amount of about 1% based on the amount of dosed liquid fuel; the main limiting reason for the amount of this addition is usually the content of soluble chlorides (alkaline Cl ^- ) in the clinker, which is usually guided by strict standard requirements resulting from concerns about excessive corrosion of steel fittings. The amount of disposed chlorinated hydrocarbons in the thermal aggregates of one cement plant is thus unfavorably low. At the same time, however, a method of the so-called low-temperature salt technology of cement clinker is known (for example, the works of Β. I. Nudelman, which resulted in AO No. 326 152 and 301315, can be cited) characterized by relatively high Cl contents in the raw material composed with regard to this clinker production technology so that the formation of hydraulically active clinker minerals of a new type takes place in the so-called chloride melt. This process is characterized by a relatively low sintering temperature (the temperature in the sintering zone is approximately 1100°C) and therefore by significantly lower demands on heat consumption and higher specific performances of the technological equipment. In the case of this production, chlorine is structurally bound in the clinker mineral called alinite (basic calcium chlorosilicate Ca22j (Si0 ₀ , ₇₅ Al0,25) O _4/8 O4Cl2 and calcium chloroaluminate CÁ12O32CI2] and there is no known danger in cements with a high content of alkaline Cl ^- . The phenomenon of the formation of the basic structural motif in alinite is registered in the USSR as discovery 210 and a copyright certificate has been granted in the USSR for the composition of the charge for the rotary kiln for the production of alinite clinker.

The disadvantage of this process is the need to prepare a raw material of a special composition containing unusual chlorine-containing additives, which complicates the composition and preparation of the raw material mixture.

The disadvantages of the above-mentioned processes are eliminated by the method according to the invention, the essence of which is the production of cement clinker from liquid or solid chlorinated organic wastes while simultaneously reducing the firing temperature, while the liquid or solid chlorinated wastes are burned in an environmentally friendly manner as a partial replacement for noble liquid or gaseous fuel. The method of burning the above-mentioned wastes can be selected either in a rotary kiln burner or under reducing conditions in an incinerator to form a mixture of hydrogen chloride and energy-rich gas fed in a secondary air stream to the rotary kiln. In both described cases of dosing: chlorine-containing organic compounds are quantitatively thermally decomposed into hydrogen chloride and other common combustion products. Hydrogen chloride immediately reacts in the rotary kiln with the alkaline components of the cement raw material, resulting in the formation of a chloride melt in which, among other things, the already mentioned minerals calcium chlorosilicate and chloroaluminate are formed as effective hydraulically active clinker components.

In terms of their properties, low-temperature salt-fired cements are the same or close to known types of Portland cements and, according to a number of indicators, they exceed their quality.

The proposed method of disposal of chlorinated hydrocarbons and other organic waste containing chlorine is characterized by a number of other undeniable advantages, including:

— the ecological advantages of this method of disposal of difficult chlorine-containing waste, especially polychlorinated biphenyls, with highly favorable economic effects;

— replacement of part of the noble fuel with environmentally problematic waste;

— possibility of disposing of solid chlorine-containing waste in an additional incinerator;

— reduction of specific heat consumption for clinker firing to current values;

— reduction of the firing temperature with a consequent effect on reducing heat losses of the aggregate and saving on lining;

— increasing the performance of the kiln unit including grate coolers, clinker and clinker mill;.

— saving of electrical energy for grinding due to the higher ability of aliriitic slimes to comminute;

— mafé. investment and operating costs, or profit from fees, companies for. disposal, difficult waste;

— easy, applicable in all types of cement plants with rotary kilns heated by liquid and gaseous fuels.

Example 1

A dry-fired clinker kiln was selected for implementation, heated with heavy fuel oil, with an average output of 62.5 tons of clinker per hour.

A. Average basic, input and output values of kiln aggregate in the normal production of classic clinker. Portland cement:

heating value of fuel oil 39, MJ. kg ^-1 dosing into the furnace:

cement raw material 103.1 t.h ^-1 fuel oil 5.51 t.h ^-1 clinker production 62.5 t.h ^-1 firing temperature 1,430 °C

B. Average input and output values for dosing polychlorinated biphenyls into fuel and producing aliquot clinker in the same kiln:

required chlorine content in clinker 2.4% heating value of fuel oil 39 MJ.kg ^-1 heating value of polychlorinated biphenyl 19 MJ. kg ^-1 (transformed oil)

Compared to average performances, in case B, the performance of the kiln unit increases by about 1/5 when the firing temperature is reduced by 250 ^° C. The resulting clinker has the following chemical and physical properties:

When ground to a specific surface area of 3,700 cubic centimeters-g ^-1 , the strength after 28 days reaches 5.9 MPa in flexure and 49.0 MPa in compression, the onset of solidification is 50 minutes.

chlorine content setting time within 10 hours in polychlorinated biphenyl 45% dosing into the oven: Content of the main clinker minerals: cement raw material 128.7 t.h. ¹ tricalcium silicate 47% fuel: fuel oil 2.65 t.h ^-1 β-dicalcium silicate 33% pcb — waste 3.34 t. hour ^-1 calcium chlorosilicate 10% clinker production 78.0 t. hour ¹ calcium chloroaluminate 5% temperature in the sluice band 1160°C calcium chloralumoferrite 2% chlorine content in clinker 2.35% OBJECT INVENTION

Claims (1)

Process for producing cement clinker from liquid or solid chlorinated organic waste while lowering the firing temperature, characterized in that liquid or solid chlorinated organic waste is dosed as a partial replacement of the noble fuel and burned either directly in the rotary kiln burner together with the main fuel or incinerator producing hydrogen chloride and energy-rich gas leading to incineration into the rotary kiln in the secondary air stream at maximum feed rate up to a maximum of 15 why. of chlorine in the raw material.