CN111559879B - Method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas - Google Patents

Method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas Download PDF

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CN111559879B
CN111559879B CN202010420763.7A CN202010420763A CN111559879B CN 111559879 B CN111559879 B CN 111559879B CN 202010420763 A CN202010420763 A CN 202010420763A CN 111559879 B CN111559879 B CN 111559879B
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gypsum
sulfur
gas
temperature
rotary kiln
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CN111559879A (en
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张国兴
陈延信
庞仁杰
赵博
韩丁
张志远
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Shanghai Sanfu Engineering Technology Co ltd
Xian University of Architecture and Technology
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Xian University of Architecture and Technology
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    • C04B7/43—Heat treatment, e.g. precalcining, burning, melting; Cooling
    • C04B7/44—Burning; Melting
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Abstract

The invention relates to a method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas, which comprises the following steps: A. preparing gas sulfur; B. preparing materials: preparing dehydrated gypsum, bauxite, a siliceous correcting material and an iron correcting material into raw materials with uniform components; C. preheating and pre-reducing: preheating raw materials, then feeding the preheated raw materials into a reduction furnace, carrying out reduction reaction with gaseous sulfur, carrying out gas-solid separation, feeding flue gas into a multi-stage suspension preheating system, and feeding the pre-reduced raw materials into a rotary kiln; D. deep reduction and clinker sintering: deep reduction reaction of the reduced raw material in a rotary kiln, and high-temperature sintering to form sulphoaluminate cement clinker; E. cooling clinker, reusing heat and purifying to prepare sulfuric acid, adding gypsum and composite material into cement clinker to obtain sulphoaluminate cement products with different performance requirements. Compared with the prior art, the method of the invention not only can consume a large amount of industrial waste residues such as industrial gypsum, but also can save limestone and natural gypsum resources, and can obtain high-quality sulphoaluminate cement and industrial sulfuric acid products.

Description

Method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas
Technical Field
The invention relates to building materials and chemical products, in particular to a method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum-containing raw materials by sulfur gas.
Background
The sulphoaluminate cement has the advantages of low alkalinity, high early strength, micro-expansion, good corrosion resistance and frost resistance, and the like, and is particularly suitable for use in coastal and cold areas and emergency repair projects. The traditional sulphoaluminate cement is prepared by sintering limestone, bauxite and gypsum which are used as raw materials at high temperature (1200-1350℃)
Figure BDA0002496880820000011
) Dicalcium silicate (C)2S) is the main mineral phase, then a small amount of gypsum is added, and the mixture is ground to obtain the sulphoaluminate cement product. Compared with common Portland cement, the consumption of the raw material limestone is reduced, and the firing temperature is 100-150 ℃ lower than that of the Portland cement at 1300-1450 ℃, so that the energy consumption and CO consumption are reduced2Also, there are significant advantages in terms of emissions. However, the existing traditional sulphoaluminate production is caused by the aluminum-containing raw material Al2O3The requirement of the content (more than 60 percent) is relatively high, not only is the cost of raw materials increased, but also the source and the drawing range of the raw materials are limited, so that the annual yield of the domestic sulphoaluminate cement is not high, the application of the series of cements is also influenced to a certain degree, the yield of the traditional sulphoaluminate cement cannot meet the market and engineering requirements, in addition, the limestone is used as a calcium source, and the CO is also increased2Discharging; how to improve the adaptability of the sulphoaluminate cement raw material, reduce the emission, and reduce the energy consumption and the raw material cost has become the key point of research of surgical researchers in the industry.
A large amount of process gypsum waste residues are generated as byproducts in the existing chemical industrial production and flue gas desulfurization, wherein the production amount of desulfurization gypsum and phosphogypsum accounts for more than 85 percent of that of industrial byproduct gypsum. At present, the annual output of desulfurized gypsum in China is about 8000 ten thousand tons, and the comprehensive utilization rate is about 83 percent; the annual output of the phosphogypsum is about 8000 ten thousand tons, and the comprehensive utilization rate is less than 40 percent; the other byproduct gypsum is about 2500 million tons, and the comprehensive utilization rate is about 40 percent. At present, the stockpiling amount of the phosphogypsum in the industrial by-product gypsum is the largest and reaches more than 5 hundred million tons. The industrial byproduct gypsum is massively stockpiled, which not only occupies land, but also wastes resources, and the contained acidity and other harmful substances easily cause pollution to the surrounding environment, thus becoming an important factor for restricting the sustainable development of the coal-fired unit flue gas desulfurization and phosphate fertilizer enterprises in China.
At present, the main utilization directions of industrial byproduct gypsum in China are cement retarder, sold or supplied outside, gypsum board and gypsum block, road building or filling, building gypsum powder and the like, and the main utilization directions are primarily elementary, low-value and small-scale utilization. The research and application of the comprehensive large-scale efficient utilization technology of the industrial by-product gypsum mainly focuses on the field of gypsum decomposition, namely that sulfur is used as sulfur and calcium is used as calcium, can be roughly divided into two directions, namely the research of a gypsum decomposition method and the research of preparing high value-added products by decomposing the industrial by-product gypsum.
The gypsum decomposition method includes a carbon reduction method and a sulfur reduction method. The industrial byproduct gypsum carbon is reduced and fired to produce the silicate cement clinker and the sulfuric acid, and is industrially applied, the gypsum raw material mostly adopts phosphogypsum, and China is represented by enterprises of Shanxi chemical industry, Shanbei chemical industry, Guizhou Jinzheng and the like, the number of the production lines which are built and operated at present reaches 11, 80 ten thousand tons of sulfuric acid and 120 ten thousand tons of cement are produced annually, and the single production line of 15 ten thousand tons of sulfuric acid and 20 ten thousand tons of silicate cement with the largest scale is Guizhou Jinzheng. After more than thirty years of development, the technology for producing the portland cement clinker by the carbon reduction of the third generation is mature. High energy consumption for reducing gypsum carbon, and the tail gas contains a large amount of CO2Tail gas containing SO2The concentration is low, and the acid preparation cost is high. The sulfur reduction method uses thiocarbon, uses sulfur to replace coke as a reducing agent, and has considerable energy-saving and emission-reducing benefits compared with the carbon reduction method.
Chinese invention patent CN101708826A 'method for reducing and decomposing phosphogypsum by sulfur', the invention discloses a method for reducing and decomposing phosphogypsum by gaseous sulfur by adopting a multi-stage decomposition process, and finally obtaining a CaO solid slag product for producing cement clinker, which comprises the following basic steps: high temperature inert gas preheatingIntroducing gaseous sulfur with the mole fraction of 10-50% into phosphogypsum (500-900 ℃ and 10-30 min) → reducing the phosphogypsum and carrying out reduction reaction (60-120 min) → cooling the CaS lump material, grinding the cooled CaS lump material into powder, mixing the powder with the phosphogypsum according to the mole ratio (1-1.5: 3) → and then reducing the CaS at high temperature
Figure BDA0002496880820000022
Cooling the CaO solid slag (1000-1400 ℃ for 30-180 min) to obtain the cement clinker for cement production; however, in the method, the mole fraction of the gaseous sulfur is low, the reaction time of the gaseous sulfur and the gypsum is long, the oxidation of CaS can be prevented by cooling the high-temperature CaS in an inert atmosphere, the cooled CaS powder and the gypsum are heated again to produce high-temperature solid slag CaO, the CaO solid slag is cooled and then is used for producing cement products according to cement ingredients, the heating and cooling are carried out for multiple times, the process flow is long and complicated, the energy consumption is high, the process flow and the heat organization are unreasonable, no specific method for obtaining the high-temperature gaseous sulfur is provided, the operation difficulty is high, and the industrial applicability is poor.
The invention patent CN 104555946B discloses a method for preparing sulfuric acid and cement clinker by reducing gypsum with sulfur gas, the sulfur gas generated by direct gasification is sent into a reducing furnace at 500-900 ℃, and the gypsum-containing raw material is added into a reducing furnace
Figure BDA0002496880820000021
Reducing 25-27% of the waste slag into CaS, delivering the discharged materials into a rotary kiln to complete deep reduction and clinker sintering, wherein the whole system is composed of sulfur gas preparation, raw material preparation, cyclone preheating, gypsum reduction, cement clinker preparation from a gypsum reduction product and acid preparation from tail gas; the method is a method for preparing sulfuric acid and coproducing portland cement clinker by reducing gypsum raw material with gas sulfur, and the mineral phase of the portland cement clinker is formed in the gypsum raw material
Figure BDA0002496880820000023
Nearly 100 percent of the calcium is decomposed into CaO and enters the cement clinker, the clinker is required to contain almost no CaS, the phosphorus and fluorine content in the industrial gypsum is required to be controlled to avoid the influence on the cement performance, and the phosphogypsum is generally required to be pretreated and processedThe process operation control difficulty is higher, and the product quality fluctuation is larger.
The research of preparing high value-added products by decomposing industrial by-product gypsum on a large scale is mainly divided into two aspects, one is that calcium oxide is taken as a product, the other is that cement clinker is taken as a product, enterprises in Shanxi chemical industry, Jinzheng chemical industry, Guizhou and the like adopt a carbon reduction method to fire the portland cement clinker, the product in the CN101708826A patent is solid slag CaO prepared by sulfur-reduced gypsum, and the product in the CN 104555946B patent is portland cement clinker prepared by sulfur-reduced gypsum. In recent years, a large amount of research work is carried out by domestic scholars in the aspect of producing sulphoaluminate or belite sulphoaluminate cement by using gypsum: the early sulphoaluminate cement production uses natural gypsum as raw material, and later reports use industrial gypsum such as phosphogypsum or desulfurized gypsum to replace natural gypsum to produce sulphoaluminate or belite sulphoaluminate cement, but in the technology, gypsum is mainly used as anhydrous calcium sulphoaluminate in a firing mineral phase
Figure BDA0002496880820000031
In (1)
Figure BDA0002496880820000032
And a small amount of free sintered at high temperature
Figure BDA0002496880820000033
The dosage of the gypsum is only 10-30%; in recent years, there have been patent and literature reports of producing sulphoaluminate or belite sulphoaluminate cement by calcining and decomposing industrial gypsum used as a raw material, and anhydrous calcium sulphoaluminate (gypsum) used not only as a clinker mineral phase in a mineral phase (calcium sulphate)
Figure BDA0002496880820000034
) In (1)
Figure BDA0002496880820000035
And a small amount of free sintered at high temperature
Figure BDA0002496880820000036
Can also replace raw material limestone as cement clinkerThe source of CaO in the material can increase the usage amount of gypsum as a raw material to the maximum extent, the usage amount of gypsum is increased to 70-85%, and CO caused by no or little limestone raw material can be reduced or avoided2And (5) discharging. Compared with portland cement, the sulphoaluminate cement has excellent performance of cement product, and may have more gypsum material, and the gypsum material need not be decomposed in 100% as Portland cement, and the gypsum material needs only to be decomposed in 60-90% to convert into CaO, and the other material needs to be decomposed in 100% to convert into CaO
Figure BDA0002496880820000037
And free
Figure BDA0002496880820000038
The form of the sodium sulfoaluminate cement is kept in a clinker mineral phase, and the advantage of preparing the sulfoaluminate or belite sulfoaluminate cement by utilizing industrial gypsum as resources is more obvious than that of preparing the silicate cement. However, how to solve the problem of effective decomposition of gypsum, SO in gas phase2Whether a sufficiently high concentration can be obtained, whether the gas concentration requirement required for co-production of sulfuric acid can be met, and whether SO in the gas phase needs to be treated2Additional desulfurization treatments to meet environmental requirements have plagued the application and development of related technologies. In the laboratory, Liuna, etc. mixes active carbon and phosphogypsum according to C/S ═ 3, then mixes them in CO2Calcining for 1h at the atmosphere of 950 ℃, then switching to the air atmosphere of 1000 ℃ for calcining for 1h, and then heating to 1200 ℃ for calcining for 30min to obtain the phosphogypsum with the decomposition rate of 91.5 percent, wherein the decomposition product of the phosphogypsum is CaO, the CaS is not contained, and the mineral phase and the performance of the calcined clinker meet the index requirements of the belite-sulphoaluminate cement clinker. Chinese invention patents CN106630701.B, CN106630702.B, CN106603703.B, CN106431030.B, CN106431031.B, CN106365476.B, CN106365477.B, CN106365478.B, etc. disclose that phosphogypsum or desulfurized gypsum is used to completely replace limestone and natural gypsum, bauxite, iron slag and/or silica and anthracite are used as auxiliary raw materials to prepare cement raw materials in a certain proportion, then the cement clinker of sulphoaluminate is prepared by carbon reduction and sectional or direct calcination, and the tail gas is calcined to co-produce sulfuric acid. Chinese patent application No. CN 201810964708.7' phosphogypsum calcined shellThe invention discloses a method for preparing a Lithothamate cement clinker and a cement clinker, and discloses a cement clinker mineral which is prepared by uniformly mixing 75-80% of phosphogypsum, 10-15% of aluminum raw material and 10-15% of silicon raw material in a proportioning manner, preheating at 1000-1100 ℃, desulfurizing for 160-180 minutes, and sintering at 1320-1350 ℃ for 60-80 minutes. The method aims to utilize the industrial by-product gypsum as the calcium and sulfur raw materials to the maximum extent, provides a good assumption for the resource utilization of the industrial by-product gypsum and can get through on the process; however, most of the above methods adopt active carbon or solid coke or anthracite as a solid reducing agent, gypsum, clay, high-quality bauxite, fly ash, iron slag, high-sulfur coal and the like are mixed and calcined together to produce sulphoaluminate or belite sulphoaluminate cement clinker, and the carbon reduction has high investment energy consumption and high CO content2Discharging and furnace gas SO2Low concentration, difficult 'two-conversion and two-absorption' of co-production sulfuric acid, high operation cost, and the problems of operation, environmental protection and economic cost.
In other patents or documents, phosphogypsum, desulfurized gypsum, titanium gypsum and other industrial by-products gypsum and limestone are used as sources of calcium and sulfur in cement ingredients, required cement raw materials are prepared by mixing the phosphogypsum, desulfurized gypsum, titanium gypsum and other industrial by-products gypsum and limestone, and the required cement raw materials and bauxite and other raw materials are calcined to prepare sulphoaluminate cement clinker or belite sulphoaluminate cement clinker, wherein a small part of the sulphoaluminate cement clinker is decomposed by gypsum to replace CaO in a part of limestone, SO that industrial waste residue gypsum cannot be effectively utilized on a large scale, and SO in flue gas is calcined2The concentration of the SO obtained by decomposing the gypsum does not meet the concentration requirement of the conventional industrial production of sulfuric acid2The burden of environmental protection is also increased.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas, which can solve the problems that the decomposition rate of gypsum is low, and the gypsum can not be used for decomposing all or most of CaO in limestone, so that the industrial waste residue gypsum is effectively utilized on a large scale.
For the description of the invention, the mineral composition of the cement is specified using the following abbreviations, unless otherwise specifically indicated:
c represents CaO;
a represents Al2O3；
F represents Fe2O3；
S represents SiO2；
Figure BDA0002496880820000051
Represents SO3；
Figure BDA0002496880820000052
Represents CaSO4；
C2S represents belite, i.e. dicalcium silicate 2 CaO. SiO2；
C3S represents tricalcium silicate 3 CaO. SiO2；
Figure BDA0002496880820000053
Represents calcium sulphoaluminate 3 CaO.3Al2O3·CaSO4；
C4AF represents tetracalcium aluminoferrite 4 CaO. Al2O3·Fe2O3；
The purpose of the invention can be realized by the following technical scheme: a method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum-containing raw materials by sulfur gas comprises the following steps:
A. preparation of gaseous sulfur
The solid or liquid sulfur is led into a sulfur melting tank and is indirectly heated to 120-160 ℃ by steam or heat conduction oil or electricity to be melted into crude sulfur liquid, the crude sulfur liquid is filtered by a sulfur filter to obtain refined sulfur liquid, the refined sulfur liquid is conveyed into a gasification furnace after being metered by a conveying pump and heated and gasified to 450-900 ℃ to obtain high-temperature gas sulfur, and the gas sulfur is conveyed into a reduction furnace by a Venturi ejector.
B. Drying, grinding and batching
Placing industrial byproduct gypsum in a conveying bed drying furnace, drying and dehydrating at 120-300 ℃, drying, grinding and primarily mixing bauxite, siliceous correcting material and ferrous correcting material in a mill, wherein the drying heat source is high-temperature surplus air discharged by a cooler, a heat source obtained by recovering waste heat of flue gas at an outlet of a first-stage cyclone preheater and a heat source obtained by recovering low-temperature waste heat in co-production sulfuric acid; mixing and homogenizing the dehydrated gypsum, the bauxite, the siliceous correcting material and the iron correcting material in a mixer, and further homogenizing in a homogenizing warehouse to obtain a raw material with uniform components. The mixture ratio of the dewatered gypsum, bauxite, siliceous correcting material and ferrous correcting material is calculated according to three values of alkalinity coefficient (C), aluminum-sulfur ratio (P) and aluminum-silicon ratio (N) which are usually required by the process of the sulphoaluminate cement clinker, and the values are used for adjusting the proportion of the sulphoaluminate raw material and controlling the components of the sulphoaluminate cement clinker to produce different varieties of sulphoaluminate cement clinker.
Furthermore, the raw material has the values of alkalinity coefficient C of 0.96-0.98, aluminum-sulfur ratio P of 3.7-3.82 and aluminum-silicon ratio N of 3.0-3.2. The weight parts of the main raw materials which meet the above rate values are as follows: 70-95 parts of gypsum, 0-35 parts of bauxite, 0-15 parts of fly ash, 0-30 parts of coal gangue, 0-10 parts of red mud, 0-8 parts of iron slag and 0-20 parts of clay, wherein the gypsum is dihydrate gypsum or semi-hydrated gypsum; the bauxite Al2O3The mass fraction is 40-75%.
Further, the industrial by-product gypsum is one kind
Figure BDA0002496880820000054
The main components of the calcium and sulfur raw materials comprise at least one or more of phosphogypsum, desulfurized gypsum, salt gypsum, titanium gypsum, fluorgypsum, nickel gypsum and manganese gypsum, and the industrial by-product phosphogypsum and desulfurized gypsum are preferably adopted, and the aluminum, siliceous and ferrous raw materials comprise at least one or more of bauxite, fly ash, coal gangue, red mud, iron slag, clay and the like.
C. Pre-heating pre-reduction
The raw meal from the step B is metered and then is fed into the topmost cyclone preheater of the multi-stage suspension preheating system and comes from the reduction furnaceThe hot air flow rapidly completes gas-solid mass transfer, heat exchange and separation in the cyclone preheater, and then sequentially completes step mass transfer, preheating and separation in 20-60 seconds through the lower-layer cyclone preheaters; the preheated raw material enters a reduction furnace, and reacts with gas sulfur in 2-45 seconds under the carrying of high-temperature flue gas from a rotary kiln, so that the sulfur and the raw material
Figure BDA0002496880820000062
The mol ratio of the sulfur to the sulfur is (0.1-0.7): 1, the temperature in the furnace is 700-980 ℃, and the calcium sulfide (CaS) and the undecomposed raw materials in the raw materials discharged from the reduction furnace
Figure BDA0002496880820000063
The molar ratio of (0.10-0.35) to (1); and after the raw materials leave the reduction furnace along with the flue gas, the raw materials enter a cyclone separator to complete gas-solid separation, the flue gas enters a multi-stage suspension preheating system, and the pre-reduced raw materials with the temperature of 700-950 ℃ enter the rotary kiln. The outlet temperature of the topmost cyclone preheater is 200-400 ℃.
Furthermore, the number of the preheater stages of the multistage suspension preheating system is 4-6, the cyclone preheater group is a single-row or double-row, and the material flow is a single-row serial or two-row cross serial.
Further, the control conditions of the reduction reaction system in the reduction furnace are as follows: (1) the temperature in the reduction furnace is 700-980 ℃; (2) the reduction reaction time is 2-45 seconds; (3) adding amount of sulfur into raw material
Figure BDA0002496880820000064
The molar ratio of (A) to (B) is 0.1-0.7: 1; (4) CaS and unreacted solid products in the outlet solid product of the reducing furnace
Figure BDA0002496880820000065
The molar ratio of (A) to (B) is 0.10-0.35: 1; (5) the outlet temperature of the top-stage cyclone preheater is 250-400 ℃, and the oxygen content of flue gas is 0.3-2.0% (v/v), preferably 0.3-1.5% (v/v).
Furthermore, the reduction furnace is a gas-solid co-flow type conveying bed reduction reaction furnace, and is a single-pass type conveying bed reactor or an external circulation type conveying bed reactor with an external separator.
Furthermore, a combustion chamber is arranged at the bottom of the reduction furnace, and fuel of the combustion chamber is one or the combination of two of liquid sulfur or gas sulfur from A. The bottom of the reduction furnace is provided with a combustion chamber for supplying
Figure BDA0002496880820000061
The high-temperature flue gas from the rotary kiln enters the reduction furnace through a combustion chamber, the rest part of the high-temperature flue gas bypasses the combustion chamber and directly enters the reduction furnace, part of the oxygen required by the combustion chamber comes from oxygen brought by tail gas of the rotary kiln, and the other part of the high-temperature flue gas passes through hot air exhausted by a supplementary cooler.
Furthermore, an outlet flue of the cyclone separator at the outlet of the reducing furnace is arranged to be an oxygen supplementing combustion chamber, supplementing air is used for consuming residual sulfur in the flue gas of the reducing furnace, the amount of air supplemented into the combustion chamber is regulated and controlled by detecting the oxygen content in the flue gas at the outlet of the top preheater by 0.3-1.5% (v/v), the cyclone preheater system is ensured to be in a weak oxidizing atmosphere, the tail gas at the outlet of the top preheater does not contain elemental sulfur, and the air supplemented by the combustion chamber adopts hot air exhausted by a cooler.
D. Deep reduction and clinker sintering
The pre-reduced raw material enters the rotary kiln through a blanking pipe, and the CaS in the raw material are mixed under the condition that the oxygen content in the smoke gas at the outlet of the rotary kiln is controlled to be less than 2 percent
Figure BDA0002496880820000073
Carrying out oxidation reduction reaction at 950-1150 ℃ in the kiln, wherein the reduction time of the material in the kiln is 5-30 min, and 60-90% of S element is SO2The other elements enter the smoke in the kiln in a form of primary solid-phase reaction; sintering the deeply reduced materials at 1100-1300 ℃ to form sulphoaluminate cement clinker, wherein the sintering time of the materials is 20-60 min.
The calcining fuel comprises one or a mixture of sulfur-containing coal, natural gas, fuel oil, coal gas and liquefied petroleum gas.
Further, the deep reduction and the clinker sintering are completed in one rotary kiln or two rotary kilns connected in series in a segmented way:
when a rotary kiln is adopted, the deep reduction of the gypsum and the sintering of the clinker are completed in the rotary kiln; firstly, the prereduced raw material enters a rotary kiln through a discharge pipe of a cyclone separator, and CaS in the raw material and the raw material are mixed
Figure BDA0002496880820000071
Finishing oxidation-reduction reaction in the kiln, wherein the temperature in the kiln of the reaction section is 950-1150 ℃, and the material is reacted in the kiln for 5-30 min; then, the material enters a sintering section, sintering of the sulphoaluminate clinker is completed along with the rise of the temperature in the kiln and the prolonging of the retention time, the temperature in the kiln of the sintering section is 1100-1300 ℃, the material stays in the kiln for 20-60 min, the air entering the kiln consists of coal-feeding air and high-temperature air discharged from a cooling machine, and the oxygen content in the flue gas of the kiln is controlled to be 0-1.5% (v/v) of weak oxidizing atmosphere; the temperature of flue gas entering the reducing furnace of the rotary kiln is 900-1100 ℃.
When two rotary kilns are adopted for serial sectional firing, deep reduction and clinker sintering are respectively completed in the two rotary kilns of the reduction rotary kiln and the sintering rotary kiln; the raw material enters a reduction rotary kiln through a discharging pipe of a cyclone separator, and CaS in the raw material and the raw material
Figure BDA0002496880820000072
Finishing oxidation-reduction reaction in a reduction kiln, wherein the temperature in the kiln is 950-1150 ℃, the material stays in the reduction kiln for 5-30 min, and the kiln inlet air consists of coal feeding air and tail gas of a sintering rotary kiln; the reducing material discharged from the reducing rotary kiln at 950-1150 ℃ enters a sintering rotary kiln through a discharging pipe to complete sintering of the sulphoaluminate clinker, the temperature in the kiln is 1100-1300 ℃, the material stays in the kiln for 20-60 min, the air entering the sintering rotary kiln consists of coal conveying air and high-temperature air discharged from a cooler, and the content of oxygen-containing gas in the flue gas at the outlet of the sintering rotary kiln is controlled to be in an oxidizing atmosphere of 2-10%; the air entering the reduction rotary kiln consists of coal feeding air and high-temperature flue gas discharged from the sintering rotary kiln, the temperature of the flue gas entering the reduction rotary kiln of the sintering rotary kiln is 1000-1200 ℃, the content of oxygen-containing gas in the flue gas at the outlet of the reduction rotary kiln is controlled to be 0-1.5% of weak oxidation atmosphere, and the temperature of the flue gas entering the reduction rotary kiln of the reduction rotary kiln is 900-1100 ℃.
E. Clinker cooling, heat recycling and purification for producing sulfuric acid
The high-temperature clinker discharged from the rotary kiln enters a cooler to exchange heat with air and be cooled to (room temperature +65) DEG C, part of the high-temperature air discharged from the cooler enters the rotary kiln to be used as combustion-supporting air of fuel, part of the high-temperature air enters a combustion chamber of a reduction furnace and an outlet combustion chamber of a cyclone separator to be used as combustion-supporting air of partial sulfur combustion, and the rest part of the high-temperature clinker is used as a drying heat source for drying gypsum and other raw materials;
and (3) after waste heat recovery and dust removal, the sulfur-containing flue gas out of the first-stage cyclone preheater enters a subsequent conventional sulfuric acid production process for washing, purifying, drying, converting, absorbing, recovering medium-low temperature waste heat, and finally treating tail gas to prepare industrial sulfuric acid products.
The cooler is one of a grate cooler, a roller cooler and a vertical cooler.
F. Preparation of cement
Cooling the clinker from the cooler in the step E, adding gypsum and the combined material, and then performing subsequent grinding processing to obtain sulphoaluminate cement products with different performance requirements, wherein the fineness of the sulphoaluminate cement products is obtained by grinding the mixture until the specific surface area is 320-420 m2/kg, preferably 360m2/kg。
According to the content of the high-temperature sintering gypsum in the clinker, the performance requirement of the sulphoaluminate cement product can be met by determining that no gypsum or little gypsum is doped through combining tests and calculation.
Further, the sulphoaluminate cement product comprises ordinary sulphoaluminate cement, high-iron sulphoaluminate cement, high-silicon sulphoaluminate cement and high-calcium sulphoaluminate cement, and clinker minerals consist of
Figure BDA0002496880820000085
:5～75％，C2S:8～60％，C4AF:3～35％，C3S:0～50％，
Figure BDA0002496880820000086
0 to 10%, and others: 0 to 5 percent.
The invention adopts a sulfur reduction method to mix gypsum and bauxiteThe ore is applied to the production of sulphoaluminate cement, and the gypsum is partially decomposed to obtain CaO which is used as calcium
Figure BDA0002496880820000081
The raw material, aluminum oxide in bauxite is used as aluminum raw material, iron is used as iron raw material, low-valence sulfur is used as reducing agent to promote gypsum decomposition reaction, and the aluminum oxide, iron and sulfur exist in the process
Figure BDA0002496880820000082
And S2Reaction to produce CaS,
Figure BDA0002496880820000083
Reaction with CaS to CaO, and CaO and Fe2O3、Al2O3、SiO2、
Figure BDA0002496880820000084
The like, the gas-phase product SO formed by the reducer in the sulphoaluminate cement clinker sintering reaction2Enter the flue gas together to improve SO2The gas is dense, which is beneficial to the subsequent acid preparation by flue gas, the productivity is improved, the energy consumption is reduced, the cost is reduced, and compared with carbon reduction, the method can reduce the emission of a large amount of CO2The method finds a new way for the direct resource utilization of the industrial byproduct gypsum, and is a new way for the high-quality and high-efficiency synergistic utilization of the industrial byproduct gypsum.
The high decomposition rate of the gypsum in the cement raw material is obtained, the CaO decomposed by the gypsum is completely utilized to replace the CaO in the limestone, the bauxite, the coal gangue and the fly ash are utilized as raw materials to meet the batching requirement of the sulphoaluminate cement, the gaseous sulfur is utilized as a reducing agent, the decomposition reaction of the gypsum is rapidly and efficiently carried out, and the high-concentration gas-phase SO is obtained2The flue gas provides the best process conditions for the subsequent co-production of sulfuric acid.
Compared with the prior art, the invention has the following advantages and characteristics:
1. compared with the prior art of preparing the sulphoaluminate cement by using the gypsum, the technology of the invention effectively adds the gypsum into the gypsum
Figure BDA0002496880820000087
The gas-solid pre-reduction reaction for converting the first decomposition step into CaS is controlled to be carried out in a reducing atmosphere in a reduction reaction furnace outside the kiln, and the CaS are reacted
Figure BDA0002496880820000088
The solid-solid redox reaction is controlled to be carried out in the rotary kiln under the weak oxidation atmosphere, 60-90% of gypsum in the raw material is decomposed into CaO, can effectively control the decomposition amount of the gypsum, realizes that the CaO decomposed from the gypsum completely replaces the CaO decomposed from the limestone in the production of the sulphoaluminate cement, ensures that the main mineral phase of the sulphoaluminate cement clinker meets the related quality index requirements, ensures that the added gypsum amount is the sum of all calcium sources and sulfur sources in the sulphoaluminate cement, can utilize industrial waste residue gypsum as resources to the utmost extent, but also can be added with more industrial gypsum to be converted into high-temperature sintered gypsum in the sulphoaluminate cement clinker through high-temperature sintering, therefore, the amount of gypsum doped after cement products are produced can be reduced, 1.1-1.3 tons of industrial gypsum can be used for producing one ton of cement clinker, the industrial gypsum can be greatly consumed, and limestone and natural gypsum resources can be saved.
2. The sulfur gas is used for replacing coke or anthracite in the existing industrial production technology to serve as a supplementary reducing agent, so that the pre-reduction reaction of gypsum decomposition is changed from solid-solid reaction into gas-solid reaction, the pre-reduction reaction of CaS generated by gypsum decomposition is successfully moved from the inside of a kiln to the outside of the kiln in a reduction decomposition furnace, the pre-reduction reaction temperature is reduced to 700-980 ℃ from 900-1200 ℃ in the traditional rotary kiln, the reaction time is shortened to 2-45 seconds from 15-40 minutes, the energy consumption of the pre-reduction reaction is reduced, the reaction time is shortened, and the gypsum decomposition efficiency is improved.
3. Mixing sulfur gas and rotary kiln flue gas, adding into the bottom of a reduction furnace, controlling the addition amount of sulfur gas to ensure the reduction atmosphere, and controlling the reduction furnace to maintain the reaction temperature
Figure BDA0002496880820000091
The partial conversion is 5-22% of the optimal mole fraction of CaS, namely the interior of the rotary kiln is effectively controlled
Figure BDA0002496880820000092
The target decomposition rate of the method ensures that the amount of the CaO decomposed from the gypsum meets the requirement of replacing limestone, the calcination decomposition is convenient to control, and the CaO required by the mineral phase of the sulphoaluminate cement clinker are effectively ensured to be formed
Figure BDA0002496880820000093
4. Gas sulfur is adopted in the reduction reaction furnace as reducing gas of solid gypsum material, heat required by gypsum pre-reduction is provided by combustion of kiln tail flue gas and part of liquid or gas sulfur, sulfur is a reducing agent and fuel and is finally converted into a precursor SO for preparing acid from flue gas2. SO in flue gas2Is a rotary kiln
Figure BDA0002496880820000094
Reaction with CaS to form SO2Reducing sulfur in reduction reaction furnace to generate SO2And SO produced by burning a small amount of sulfur as fuel2The SO in the final tail gas of the system is obtained under the condition of minimum control of the amount of sulfur used as a reducing agent2Highest concentration, SO2The mole fraction of the components can be improved to 12-18%, and the subsequent sulfuric acid production SO can be realized2The conversion, absorption, optimization of system process parameters and improvement of production capacity are extremely favorable, the reduction of equipment specification of a sulfuric acid production system or the improvement of the production capacity of a device are facilitated, the two-conversion two-absorption and medium and low temperature waste heat recovery can be realized, the specification of process equipment is small, and the comprehensive operation cost is low.
5. As 5-22% of gypsum is quickly converted into CaS in the reduction furnace outside the kiln, the decomposition temperature in the kiln is also reduced to 950-1150 ℃, the temperature of materials entering the rotary kiln is increased by more than 150 ℃ compared with the prior temperature, and the retention time of the materials in the rotary kiln is greatly shortened.
6. Because it is completed in the reduction furnace outside the kiln
Figure BDA0002496880820000095
Partial conversion to CaS, only carried out in the kiln
Figure BDA0002496880820000096
Compared with the traditional carbon reduction kiln, the deep oxidation-reduction reaction for generating calcium oxide by CaS is easy to operate and control, the reaction time is shortened to 5-30 minutes, the length of the rotary kiln is shortened to 1/4, the reaction efficiency and the volume heat load of the rotary kiln are improved, the production control is easy to carry out, and the production efficiency is improved.
7. If the phosphogypsum is adopted as the raw material, the phosphogypsum contains a small amount of P2O5、MgO、Na2O、K2O, F, P is formed when Portland cement is burned2O5The existence of impurities such as F and the like is harmful to the quality of cement, and phosphogypsum needs to be pretreated to ensure P in the raw material gypsum2O5The amount of the catalyst is controlled within a certain range; while in the sulphoaluminate cement sintering, a small amount of P is contained in the gypsum2O5、MgO、Na2O、K2O, F, etc. in the sintering process, it is beneficial to the formation of the mineral phase of cement sintering, and the mineral phase is solidified in the sintering process without affecting the performance of sulphoaluminate cement, so it does not need to specially pre-treat phosphogypsum.
8. Reduces CO from multiple aspects of using industrial gypsum to replace limestone as a calcium source, using sulfur gas to replace coke or sulfur-containing coal as a reducing agent, reasonably organizing the process to reduce energy consumption and the like2Generation and discharge, which is beneficial to environmental protection.
9. The invention has the advantages of simple process flow, strong system control index implementability, convenient operation and management, advanced process equipment, less device investment, low energy consumption, low operation cost and high automation degree.
Drawings
FIG. 1 is a general process flow diagram of the present invention;
FIG. 2 is a process flow diagram of example 1 of the present invention;
FIG. 3 is a process flow diagram of example 2 of the present invention;
FIG. 4 is a process flow diagram of example 3 of the present invention;
FIG. 5 is a process flow diagram of example 4 of the present invention;
FIG. 6 is a flowchart of the process of example 5 of the present invention;
FIG. 7 is a process flow diagram of example 6 of the present invention;
FIG. 8 is a process flow diagram of example 7 of the present invention;
FIG. 9 is a process flow diagram of example 8 of the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
As shown in fig. 1, which is a general process flow diagram of the present invention, industrial gypsum is used as a calcareous sulfur raw material, one or more of high-grade bauxite, coal gangue, fly ash, red mud, clay and iron slag are used as an aluminum raw material, a siliceous raw material, an iron raw material and a correcting material ingredient, and sulfur gas is used as a reducing agent to prepare sulphoaluminate cement and sulfuric acid, and the method specifically comprises the following steps:
A. preparation of gaseous sulfur
Introducing solid or liquid sulfur into a sulfur melting tank, heating to 120-160 ℃ to melt into crude sulfur liquid, filtering by a sulfur filter to obtain refined sulfur liquid, sending into a gasification furnace, heating and gasifying to 450-900 ℃ to obtain high-temperature gas sulfur, and sending the gas sulfur into a reduction furnace by a Venturi ejector;
B. ingredients
Mixing and homogenizing the dehydrated gypsum and the ingredients in a mixer, and further homogenizing in a homogenizing warehouse to obtain raw materials with uniform components;
C. pre-heating pre-reduction
The raw materials are sent into a multi-stage suspension preheating system for step preheating, the preheated raw materials enter a reduction furnace to perform reduction reaction with sulfur gas entering the reduction furnace in the step A, the reacted materials enter a cyclone separator to complete gas-solid separation, the flue gas enters the multi-stage suspension preheating system, and the pre-reduced raw materials enter a rotary kiln;
D. deep reduction and clinker sintering
Under the weak oxidation atmosphere, deep reduction reaction of the pre-reduced raw material occurs in the rotary kiln, and the deep reduced raw material is sintered at high temperature to form cement clinker;
E. clinker cooling, heat recycling and purification for producing sulfuric acid
The high-temperature cement clinker out of the rotary kiln enters a cooler to exchange heat with cooling air, the heat is recovered, and the sulfur-containing flue gas out of a first-stage cyclone preheater in the multi-stage suspension preheating system enters a subsequent conventional sulfuric acid production process to prepare an industrial sulfuric acid product after waste heat recovery and dust removal purification;
F. preparation of cement
And E, adding gypsum and combined materials into the cement clinker from the cooler in the step E, and then carrying out subsequent grinding processing to obtain sulphoaluminate cement products with different performance requirements.
The following is a detailed description of specific examples.
Example 1:
the technological process is shown in figure 2, desulfurized gypsum and high-grade bauxite are used as raw materials, the raw materials are dried and ground to be more than 95-80 mu m, most of fly ash generated by burning rotary kiln fuel coal enters clinker, and the chemical components of the raw materials and raw materials are shown in table 1.
TABLE 1 chemical composition of raw materials and raw meal
Figure BDA0002496880820000111
Figure BDA0002496880820000121
The dihydrate desulfurized gypsum and the high-grade bauxite raw material comprise the following components in parts by mass: 76.1 parts of dihydrate desulfurized gypsum and 23.9 parts of high-grade bauxite are uniformly mixed by a proportioning scheme, the raw materials are dried, ground and homogenized, and the obtained raw materials are metered and sent to the mixer C1aGas inlet of cyclone preheater (in this embodiment the multi-stage suspension preheating system comprises 4 stages of cyclone preheater, where C1aThe topmost cyclone preheater) with SO-containing gas from rotary kilns and transport bed reduction furnaces2Hot gasThe solid raw material is subjected to gas-solid countercurrent contact type heat exchange, the temperature of the solid raw material is raised to 820 ℃ after 4-stage heat exchange from top to bottom, and the solid raw material enters a single pass type conveying bed reduction furnace. The method comprises the following steps of (1) introducing solid or liquid sulfur into a sulfur melting tank by a sulfur gas gasifier (comprising a sulfur melting tank, a sulfur filter and a gasification furnace, indirectly heating the solid or liquid sulfur to 120-160 ℃ by adopting steam or heat conducting oil or electricity, melting the sulfur into crude sulfur liquid, filtering the crude sulfur liquid by the sulfur filter to obtain refined sulfur liquid, feeding the refined sulfur liquid into a gasification furnace by a delivery pump after metering, heating and gasifying the refined sulfur liquid to obtain high-temperature gas sulfur), wherein the temperature of the superheated sulfur gas is 680 ℃, and feeding the high-temperature gas sulfur into a combustion chamber at the bottom of the reduction furnace by a Venturi ejector; meanwhile, high-temperature flue gas at 930 ℃ from the rotary kiln also enters a combustion chamber of the reduction furnace, and the oxygen content of the flue gas is 0.5 percent. The center temperature of the reducing furnace of the conveying bed is 890 ℃, the minimum retention time of the materials in the furnace is 30.5 seconds, and the amount of the liquid sulfur entering the sulfur gasifier is adjusted to control the gas sulfur and the raw materials
Figure BDA0002496880820000123
In a molar ratio of 0.3:1, calcium sulfide and unreacted in the material leaving the reduction furnace
Figure BDA0002496880820000124
In a molar ratio of 0.21: 1. In sulfur gas and raw meal
Figure BDA0002496880820000125
Quickly generate gas-solid reduction reaction to generate solid CaS and SO2Gas, gas mixture discharged from the outlet of the reduction furnace passes through a cyclone separator C5abGas-solid separation is carried out, and the gas continuously passes upwards through two parallel C paths4a→C3a→C2a→C1a、C4b→C3b→C2b→C1bWith solid raw meal in series at C1a→C1b→C2a→C2b→C3a→C3b→C4a→C4bCarrying out mass and heat transfer exchange at C5abAir at 920 ℃ from a cooler is supplemented to the combustion chamber at the air outlet, SO that residual sulfur gas in the gas phase is completely combusted to generate SO2，C1abThe volume concentration of oxygen in the outlet waste gas is 1.6 percent and the SO content is2The volume concentration is 16.8 percent, the temperature of the waste gas is 320 ℃, and the waste gas is further subjected to waste heat recovery and dust removal and then is sent to a subsequent purification sulfuric acid preparation system.
From C5abThe separated solid material is sent into a reduction rotary kiln through a discharge pipe to generate CaS and
Figure BDA0002496880820000126
the temperature of a deep reduction reaction section in the kiln is 1030-1170 ℃; and (3) feeding the reduced material into a sintering rotary kiln, sintering at high temperature to form ordinary sulphoaluminate cement clinker minerals, wherein the temperature of a sintering section in the kiln is 1150-1250 ℃, and discharging the clinker from a kiln head to enter a clinker cooler.
The chemical composition of the clinker and the mineral composition of the clinker measured by the XRD diffraction quantitative analysis method are shown in tables 2 and 3, respectively.
TABLE 2 chamotte chemical composition
Figure BDA0002496880820000122
Figure BDA0002496880820000131
TABLE 3 chamotte mineral phase composition
Figure BDA0002496880820000132
Cooling clinker from a cooler, adding gypsum and combined materials, and then performing subsequent grinding processing to obtain sulphoaluminate cement products with different performance requirements, wherein the fineness of the sulphoaluminate cement products is obtained by grinding the mixture until the specific surface area is 400m2/kg。
Example 2
The process flow is shown in figure 3, desulfurized gypsum, bauxite, fly ash and iron slag are used as raw materials, the raw materials are dried and ground to be more than 95-80 mu m, most of fly ash generated by burning rotary kiln fuel coal enters clinker, and the chemical components of the raw materials and raw materials are shown in table 4.
TABLE 4 chemical composition of raw materials and raw meal
Item CaO SiO2 Al2O3 Fe2O3 MgO TiO2 Na2O SO3 LOSS Is totaled
Desulfurized gypsum 34.35 1.56 1.78 1.15 2.24 0.12 0.15 41.56 17.06 99.97
Bauxite ore 1.50 14.54 72.34 3.37 0.07 0.66 0.24 0.13 6.98 99.83
Fly ash 1.48 43.50 35.38 1.92 0.70 1.18 0.33 0.68 14.77 99.94
Iron slag 40.46 12.24 1.93 27.64 4.74 0.00 0.00 2.98 9.86 99.85
Raw material 28.19 7.02 13.33 3.40 2.03 0.26 0.16 30.51 15.10 100.00
The raw materials of the dihydrate desulfurized gypsum, the high-grade bauxite, the fly ash and the iron slag comprise the following components in parts by weight: 72.7 parts of dihydrate desulfurized gypsum, 12.9 parts of high-grade bauxite, 7.2 parts of fly ash and 7.2 parts of iron slag are uniformly mixed by a batching scheme. Drying and grinding the raw materials, mixing and homogenizing, metering the raw materials, and feeding into a mixer C1aGas inlet of cyclone preheater, and SO-containing gas from rotary kiln and transfer bed reduction furnace2The hot gas carries out gas-solid countercurrent contact heat exchange, the solid raw material passes through 4 stages of heat exchange from top to bottom, the temperature of the raw material is raised to 870 ℃, and the raw material enters a single-pass reducing furnace of a conveying bed. The superheated sulfur gas from the sulfur gas gasifier is delivered into a combustion chamber at the bottom of the reduction furnace through a Venturi ejector at the temperature of 700 ℃; meanwhile, 960 ℃ high-temperature flue gas from the rotary kiln also enters a combustion chamber of the reduction furnace, and the oxygen content of the flue gas is 0.5 percent. The center temperature of the reducing furnace of the conveying bed is 880 ℃, the minimum retention time of the materials in the furnace is 20 seconds, and the gas sulfur and the raw materials are controlled by adjusting the amount of the liquid sulfur entering the sulfur gasifier
Figure BDA0002496880820000133
In a molar ratio of 0.31:1, sulfur in the material discharged from the reduction furnaceCalcium dissolving with unreacted
Figure BDA0002496880820000134
In a molar ratio of 0.22: 1. In sulfur gas and raw meal
Figure BDA0002496880820000144
Quickly generate gas-solid reduction reaction to generate solid CaS and SO2Gas, gas mixture discharged from the outlet of the reduction furnace passes through a cyclone separator C5abGas-solid separation is carried out, and the gas continuously passes upwards through two parallel C paths4a→C3a→C2a→C1a、C4b→C3b→C2b→C1bWith solid raw meal in series in C1a→C1b→C2a→C2b→C3a→C3b→C4a→C4bCarrying out mass and heat transfer exchange at C5abThe combustion chamber at the air outlet replenishes 900 ℃ air from a cooler, SO that residual sulfur gas in the gas phase is completely combusted to generate SO2，C1abThe volume concentration of oxygen in the outlet waste gas is 1.0 percent and SO2The volume concentration is 17 percent, the temperature of the waste gas is 280 ℃, and the waste gas is further subjected to waste heat recovery and dust removal and is sent to a subsequent purification sulfuric acid preparation system.
From C5abThe separated solid material is sent into the rotary kiln through a discharge pipe to generate CaS and
Figure BDA0002496880820000145
the temperature of a deep reduction section in the kiln is 1050-1180 ℃, the retention time is prolonged along with the temperature rise, the reduced materials enter a sintering section and are sintered at high temperature to form high-iron sulphoaluminate cement clinker minerals, the temperature of the sintering section in the kiln is 1170-1280 ℃, and the clinker is discharged from a kiln head and enters a clinker cooler.
The chemical components of the clinker and the mineral composition of the clinker determined by the XRD diffraction quantitative analysis method are respectively shown in tables 5 and 6.
TABLE 5 chamotte chemical composition
Figure BDA0002496880820000141
TABLE 6 Clinker mineral phase composition
Figure BDA0002496880820000142
Cooling clinker from a cooler, adding gypsum and a combined material, and then performing subsequent grinding processing to obtain high-iron sulphoaluminate cement products with different performance requirements, wherein the fineness of the products is obtained by grinding the materials until the specific surface area is 340m2/kg。
Example 3
The process flow is shown in figure 4, dihydrate phosphogypsum, high-grade bauxite and coal gangue are used as raw materials, the raw materials are dried and ground into powder of more than 95-80 mu m, most of fly ash generated by burning rotary kiln fuel coal enters clinker, and the chemical components of the fly ash are shown in table 7.
TABLE 7 chemical composition of raw materials and raw meal
Figure BDA0002496880820000143
Figure BDA0002496880820000151
The raw materials of the dihydrate phosphogypsum, the high-grade bauxite and the coal gangue comprise the following components in parts by weight: 75.1 parts of dihydrate phosphogypsum, 20.8 parts of high-grade bauxite and 4.1 parts of coal gangue are uniformly mixed by a proportioning scheme, the raw materials are dried, ground, mixed and homogenized, and raw materials are metered and sent to a mixer C1Gas inlet of cyclone preheater, and SO-containing gas from rotary kiln and transport bed reduction furnace2The hot gas carries out gas-solid countercurrent contact type heat exchange, solid raw materials are subjected to 5-stage heat exchange from top to bottom, the temperature of the materials is raised to 830 ℃, and the materials enter a single-pass type conveying bed reduction furnace. The superheated sulfur gas from the sulfur gas gasifier is at the temperature of 750 ℃ and is sent into a combustion chamber at the bottom of the reducing furnace through a Venturi ejector; at the same time, 940 ℃ high-temperature flue gas from the rotary kiln also enters the kilnThe oxygen content of the flue gas of the original furnace combustion chamber is 1.0 percent. The center temperature of the reducing furnace of the conveying bed is 900 ℃, the minimum residence time of the materials in the furnace is 33 seconds, and the gas sulfur and the raw materials are controlled by adjusting the amount of the liquid sulfur entering the sulfur gasifier
Figure BDA0002496880820000153
In a molar ratio of 0.33:1, calcium sulfide and unreacted materials in the materials discharged from the reduction furnace
Figure BDA0002496880820000154
In a molar ratio of 0.19: 1. Of sulfur gas and raw meal
Figure BDA0002496880820000155
Quickly generate gas-solid reduction reaction to generate solid CaS and SO2Gas, gas mixture discharged from the outlet of the reduction furnace passes through a cyclone separator C6Gas-solid separation is carried out, and the gas continuously passes through the C5→C4→C3→C2→C1With solid raw materials in C1→C2→C3→C4→C5Carrying out mass and heat transfer exchange at C6The air at 940 ℃ from the cooler is supplemented to the combustion chamber at the air outlet, SO that the residual sulfur gas in the gas phase is completely combusted to generate SO2，C1The volume concentration of oxygen in the outlet waste gas is 1.5 percent and the volume concentration of SO2The volume concentration is 14.5 percent, the temperature of the waste gas is 350 ℃, and the waste gas is further subjected to waste heat recovery and dust removal and then is sent to a subsequent purification sulfuric acid preparation system.
From C6The separated solid material is sent into a reduction rotary kiln through a discharge pipe to generate CaS and
Figure BDA0002496880820000156
the temperature in the kiln is 1000-1160 ℃; and (3) the reduced materials enter a sintering rotary kiln and are sintered at high temperature to form ordinary sulphoaluminate cement clinker minerals, the temperature in the kiln ranges from 1140 ℃ to 1260 ℃, and the clinker is discharged from the head of the sintering rotary kiln and enters a clinker cooling machine.
The chemical components of the clinker and the mineral composition of the clinker determined by the XRD diffraction quantitative analysis method are respectively shown in tables 8 and 9.
TABLE 8 chamotte chemical composition
Figure BDA0002496880820000152
Figure BDA0002496880820000161
TABLE 9 chamotte mineral phase composition
Figure BDA0002496880820000162
Cooling clinker from a cooler, adding gypsum and a combined material, and then performing subsequent grinding processing to obtain sulphoaluminate cement products with different performance requirements, wherein the fineness of the sulphoaluminate cement products is obtained by grinding the mixture until the specific surface area is 360m2/kg。
Example 4
The process flow is shown in figure 5, titanium gypsum and high-grade bauxite are used as raw materials, the raw materials are dried and ground to be more than 95-80 mu m, most of fly ash generated by burning rotary kiln fuel coal enters clinker, and the chemical components of the fly ash are shown in table 10.
TABLE 10 chemical composition of raw materials and raw meal
Item CaO SiO2 Al2O3 Fe2O3 MgO TiO2 Na2O SO3 LOSS Total up to
Titanium gypsum 29.50 2.50 2.03 2.64 0.83 1.60 0.15 37.54 20.90 99.69
Bauxite ore 1.50 6.07 65.89 4.11 0.07 0.70 0.24 0.19 21.08 99.85
Raw material 23.68 3.26 15.49 2.86 0.67 1.41 0.17 29.78 22.58 100.00
The raw materials of the dihydrate titanium gypsum and the high-grade bauxite comprise the following components in parts by weight: 79.0 parts of dihydrate titanium gypsum and 21.0 parts of high-grade bauxite are uniformly mixed, the raw materials are dried, ground and homogenized, and the raw materials are metered and sent to the mixer C1Gas inlet of cyclone preheater, and SO-containing gas from rotary kiln and transport bed reduction furnace2The hot gas carries out gas-solid countercurrent contact type heat exchange, the solid raw material is subjected to 5-stage heat exchange from top to bottom, the material temperature is raised to 850 ℃, and the solid raw material enters a single-pass type conveying bed reduction furnace. The superheated sulfur gas from the sulfur gas gasifier is delivered into a combustion chamber at the bottom of the reduction furnace through a Venturi ejector at the temperature of 670 ℃; meanwhile, high-temperature flue gas at 960 ℃ from the rotary kiln also enters a combustion chamber of the reduction furnace, and the oxygen content of the flue gas is 1.1 percent. The center temperature of the reducing furnace of the conveying bed is 910 ℃, the minimum residence time of the materials in the furnace is 26 seconds, and the amount of the liquid sulfur entering the sulfur gasifier is adjusted to control the gas sulfur and the raw materials
Figure BDA0002496880820000163
In a molar ratio of 0.29:1, calcium sulfide and unreacted materials in the materials discharged from the reduction furnace
Figure BDA0002496880820000164
In a molar ratio of 0.19: 1. SulfurOf sulphur gas and raw meal
Figure BDA0002496880820000165
Quickly generate gas-solid reduction reaction to generate solid CaS and SO2Gas, gas mixture discharged from the outlet of the reduction furnace passes through a cyclone separator C6Gas-solid separation is carried out, and the gas continuously passes through the C5→C4→C3→C2→C1With solid raw materials in C1→C2→C3→C4→C5Carrying out mass and heat transfer exchange at C6The air at 940 ℃ from the cooler is supplemented to the combustion chamber at the air outlet, SO that the residual sulfur gas in the gas phase is completely combusted to generate SO2，C1The volume concentration of oxygen in the outlet waste gas is 2.0 percent and SO2The volume concentration is 15.7 percent, the temperature of the waste gas is 310 ℃, and the waste gas is further subjected to waste heat recovery and dust removal and then is sent to a subsequent purification sulfuric acid preparation system.
From C6The separated solid material is sent into the rotary kiln through a discharge pipe to generate CaS and
Figure BDA0002496880820000173
the temperature of the deep reduction section in the kiln is 1020-1150 ℃, the retention time is prolonged along with the temperature rise, the reduced materials enter a sintering section and are sintered at high temperature to form high-iron sulphoaluminate cement clinker minerals, the temperature of the sintering section in the kiln is 1150-1270 ℃, and the clinker is discharged from the kiln head and enters a clinker cooler.
The chemical composition of the clinker and the mineral composition of the clinker determined by the XRD diffraction quantitative analysis method are shown in tables 11 and 12 respectively.
TABLE 11 chamotte chemical composition
Figure BDA0002496880820000171
TABLE 12 chamotte mineral phase composition
Figure BDA0002496880820000172
Cooling clinker from a cooler, adding gypsum and a combined material, and then performing subsequent grinding processing to obtain high-iron sulphoaluminate cement products with different performance requirements, wherein the fineness of the products is obtained by grinding the materials until the specific surface area is 340m2/kg。
Example 5
The technological process is shown in figure 6, titanium gypsum, bauxite and fly ash are used as raw materials, the raw materials are dried and ground to be more than 95-80 mu m, most of the fly ash generated by burning the rotary kiln fuel coal enters clinker, and the chemical components of the fly ash are shown in table 13.
TABLE 13 chemical composition of raw materials and raw meal
Item CaO SiO2 Al2O3 Fe2O3 MgO Na2O SO3 LOSS Total up to
Titanium gypsum 29.50 2.50 2.03 2.64 0.83 0.15 37.54 20.90 99.69
Bauxite ore 1.50 24.76 54.39 1.53 0.07 0.24 0.45 17.03 100.67
Fly ash 1.48 43.50 35.38 1.92 0.70 0.33 0.68 14.77 99.94
Raw material 25.00 6.50 10.14 2.47 0.72 0.17 31.58 21.94 100.00
The raw materials of the dihydrate titanium gypsum and the bauxite comprise the following components in parts by weight: 83.7 parts of titanium dihydrate gypsum, 14.2 parts of bauxite and 2.1 parts of fly ash are uniformly mixed, and the raw materials are fed into the mixer after being measured1Gas inlet of cyclone preheater, and SO-containing gas from rotary kiln and transfer bed reduction furnace2And (3) carrying out gas-solid countercurrent contact heat exchange on the hot gas, carrying out 4-stage heat exchange on solid raw materials from top to bottom, increasing the material temperature to 875 ℃, and feeding the solid raw materials into an external circulating type conveying bed reduction furnace of an external separator. The superheated sulfur gas from the sulfur gas gasifier is at 650 ℃ and is sent into a combustion chamber at the bottom of the reducing furnace through a Venturi ejector; meanwhile, 990 ℃ high-temperature flue gas from the rotary kiln also enters a combustion chamber of the reduction furnace, and the oxygen content of the flue gas is 0.3 percent. The central temperature of the reducing furnace of the conveying bed is 830 ℃, the most probable residence time of the materials in the intracranial space is 28 seconds, and the amount of the liquid sulfur entering the sulfur gasifier is adjusted to control the gas sulfur and the raw materials
Figure BDA0002496880820000183
In a molar ratio of 0.26:1, calcium sulfide and unreacted materials in the materials discharged from the reduction furnace
Figure BDA0002496880820000184
In a molar ratio of 0.22: 1. In sulfur gas and raw meal
Figure BDA0002496880820000185
Quickly generate gas-solid reduction reaction to generate solid CaS and SO2Gas, gas mixture discharged from the outlet of the reduction furnace passes through a cyclone separator C5Gas-solid separation is carried out, and the gas continuously passes through the C4→C3→C2→C1Solid raw meal in C1→C2→C3→C4Carrying out mass and heat transfer exchange at C5The air at 935 ℃ from the cooler is supplemented to the air outlet combustion chamber, SO that the residual sulfur gas in the gas phase is completely combusted to generate SO2，C1The volume concentration of oxygen in the outlet waste gas is 0.8 percent and SO2The volume concentration is 14.4 percent, the temperature of the waste gas is 270 ℃, and the waste gas is further subjected to waste heat recovery and dust removal and then is sent to a subsequent purification sulfuric acid preparation system.
From C5The separated solid material is sent into a reduction rotary kiln through a discharge pipe to generate CaS and
Figure BDA0002496880820000186
the temperature in the kiln is 1000-1150 ℃; and (3) the discharged materials enter a sintering rotary kiln to be sintered at high temperature to form high-silicon sulphoaluminate cement clinker minerals, the temperature in the kiln is 1100-1260 ℃, and the clinker is discharged from the kiln head and enters a clinker cooling machine.
The chemical composition of the clinker and the mineral composition of the clinker determined by the XRD diffraction quantitative analysis method are shown in tables 14 and 15 respectively.
TABLE 14 chamotte chemical composition
Figure BDA0002496880820000181
TABLE 15 mineral phase composition of clinker
Figure BDA0002496880820000182
Cooling clinker from a cooler, adding gypsum and combined materials, and then performing subsequent grinding processing to obtain high-silicon sulphoaluminate cement products with different performance requirements, wherein the fineness of the products is obtained by grinding the clinker to the specific surface area of 370m2/kg。
Example 6
The process flow is shown in figure 7, dihydrate phosphogypsum, high-grade bauxite and coal gangue are used as raw materials, the raw materials are dried and ground into powder of more than 95-80 mu m, most of fly ash generated by burning rotary kiln fuel coal enters clinker, and the chemical components of the fly ash are shown in table 16.
TABLE 16 chemical composition of raw materials and raw meal
Item CaO SiO2 Al2O3 Fe2O3 MgO P2O5 Na2O SO3 LOSS Total up to
Phosphogypsum 32.56 4.76 0.97 0.39 0.31 1.05 0.30 43.63 15.98 99.95
Bauxite ore 2.30 2.23 71.41 11.57 0.07 0.00 0.12 0.16 16.82 99.96
Coal gangue 21.82 30.15 16.56 3.45 0.71 0.00 0.00 11.95 15.27 100.12
Raw material 29.42 11.81 5.67 1.30 0.42 0.78 0.22 34.60 15.76 100.00
The raw materials of the dihydrate phosphogypsum, the high-grade bauxite and the coal gangue comprise the following components in parts by weight: 71.7 parts of dihydrate phosphogypsum, 0.5 part of high-grade bauxite and 27.8 parts of coal gangue are uniformly mixed, and raw materials are fed into the mixer after being measured1Gas inlet of cyclone preheater, and SO-containing gas from rotary kiln and transport bed reduction furnace2The hot gas carries out gas-solid countercurrent contact type heat exchange, solid raw materials are subjected to 6-stage heat exchange from top to bottom, the material temperature is raised to 875 ℃, and the solid raw materials enter an external circulating type conveying bed reducing furnace of an external separator. The superheated sulfur gas from the sulfur gas gasifier is at 650 ℃ and is sent into a combustion chamber at the bottom of the reducing furnace through a Venturi ejector; meanwhile, 990 ℃ high-temperature flue gas from the rotary kiln also enters a combustion chamber of the reduction furnace, and the oxygen content of the flue gas is 0.3 percent. The central temperature of the reducing furnace of the conveying bed is 830 ℃, the material stays in the intracranial space for 18 seconds at most, and the amount of the liquid sulfur entering the sulfur gasifier is adjusted to control the gas sulfur and the raw material
Figure BDA0002496880820000191
In a molar ratio of 0.26:1, calcium sulfide and unreacted materials in the materials discharged from the reduction furnace
Figure BDA0002496880820000192
In a molar ratio of 0.22: 1. In sulfur gas and raw meal
Figure BDA0002496880820000193
Quickly generate gas-solid reduction reaction to generate solid CaS and SO2Gas, gas mixture discharged from the outlet of the reduction furnace passes through a cyclone separator C7Gas-solid separation is carried out, and the gas continuously passes through the C6→C5→C4→C3→C2→C1With solid raw materials in C1→C2→C3→C4→C5→C6Carrying out mass and heat transfer exchange at C7The air at 935 ℃ from the cooler is supplemented to the air outlet combustion chamber, SO that the residual sulfur gas in the gas phase is completely combusted to generate SO2，C1The volume concentration of oxygen in the outlet waste gas is 0.8 percent and SO2The volume concentration is 14.4 percent, the temperature of the waste gas is 270 ℃, and the waste gas is further subjected to waste heat recovery and dust removal and then is sent to a subsequent purification sulfuric acid preparation system.
From C7The separated solid material is sent into the rotary kiln through a discharge pipe to generate CaS and
Figure BDA0002496880820000194
the temperature of the deep reduction section in the kiln is 1000-1150 ℃, the retention time is prolonged along with the temperature rise, the reduced materials enter a sintering section and are sintered at high temperature to form high-calcium sulphoaluminate cement clinker minerals, the temperature in the kiln is 1100-1260 ℃, and the clinker is discharged from the kiln head and enters a clinker cooler.
The chemical compositions of the clinker and the mineral compositions of the clinker determined by the XRD diffraction quantitative analysis method are shown in tables 17 and 18 respectively.
TABLE 17 chamotte chemical composition
Figure BDA0002496880820000201
TABLE 18 mineral phase composition of clinker
Figure BDA0002496880820000202
Cooling clinker from a cooler, adding gypsum and a combined material, and then performing subsequent grinding processing to obtain high-calcium sulphoaluminate cement products with different performance requirements, wherein the fineness of the products is obtained by grinding the materials until the specific surface area is 380m2/kg。
Example 7
Referring to fig. 8, a method for producing sulphoaluminate cement and co-producing sulphuric acid by reducing gypsum-containing raw meal with sulphur gas comprises the following steps:
A. preparation of gaseous sulfur
Solid sulfur is led into a sulfur melting tank and is heated to 120 ℃ by steam to be melted into crude sulfur liquid, the crude sulfur liquid is filtered by a sulfur filter to obtain refined sulfur liquid, the refined sulfur liquid is conveyed into a gasification furnace after being metered by a conveying pump and heated and gasified to 460 ℃ to obtain high-temperature gas sulfur, and the gas sulfur is conveyed into a reduction furnace by a Venturi ejector.
B. Drying, grinding and batching
The industrial by-product gypsum is placed in a conveying bed drying furnace to be dried and dehydrated at 120 ℃, the bauxite, the siliceous correcting material and the ferrous correcting material are dried, ground and primarily mixed in a mill, and a drying heat source is high-temperature surplus air discharged by a cooler (an optional grate cooler), a heat source recovered by flue gas at the outlet of a first-stage cyclone preheater and a heat source obtained by low-temperature waste heat recovery in co-production of sulfuric acid; mixing and homogenizing the dehydrated gypsum, the bauxite, the siliceous correcting material and the iron correcting material in a mixer, and further homogenizing in a homogenizing warehouse to obtain a raw material with uniform components. The mixture ratio of the dehydrated gypsum, bauxite, siliceous correcting material and ferrous correcting material is calculated according to three values of alkalinity coefficient (C), aluminum-sulfur ratio (P) and aluminum-silicon ratio (N) which are usually required by the sulphoaluminate cement clinker process, and the values are used for adjusting the proportion of sulphoaluminate raw material and controlling the components of the sulphoaluminate cement clinker to produce the high-calcium sulphoaluminate cement clinker.
In the embodiment, phosphogypsum, coal gangue, bauxite, red mud, clay, iron slag and fly ash are used as raw materials, the raw materials are dried and ground into powder of more than 95-80 microns, most of the fly ash generated by burning the fuel coal of the rotary kiln enters clinker, and the chemical components of the fly ash are shown in Table 19.
TABLE 19 chemical composition of raw materials and raw meal
Item CaO SiO2 Al2O3 Fe2O3 MgO P2O5 Na2O SO3 LOSS Total up to
Phosphogypsum 32.56 4.76 0.97 0.39 0.31 1.05 0.30 43.63 15.98 99.95
Coal gangue 21.82 30.15 16.56 3.45 0.71 0.09 0.00 11.95 15.27 100.00
Bauxite ore 2.42 20.34 44.18 12.86 0.09 0.00 0.21 0.37 18.82 99.30
Red mud 11.47 20.35 23.37 15.84 0.08 0.00 4.11 1.26 15.52 92.00
Clay clay 0.45 22.00 60.00 2.80 0.00 0.09 0.00 0.54 12.00 97.88
Iron slag 29.45 12.35 2.95 53.36 0.00 0.00 0.00 0.53 1.32 99.96
Coal ash 1.48 43.50 35.38 1.92 0.70 0.00 0.33 0.68 14.77 98.76
Raw material 28.80 10.39 5.72 1.57 0.37 0.85 0.31 36.28 15.70 100.00
The main raw materials comprise the following ingredients in parts by weight: 80.2 parts of phosphogypsum, 9.5 parts of coal gangue, 0.5 part of bauxite, 1 part of red mud, 1 part of iron slag, 0.5 part of clay and 7.2 parts of fly ash; the bauxite Al2O3The mass fraction is 44.18%, and the industrial byproduct gypsum is phosphogypsum dihydrate.
C. Preheating and prereducing
B, metering the raw materials from the step B, feeding the raw materials into a topmost cyclone preheater of a 4-level suspension preheating system, rapidly completing gas-solid heat exchange and separation with hot air flow from a reduction furnace in the cyclone preheater, and sequentially completing step preheating within 20 seconds through all levels of cyclone preheaters on the lower layer; the preheated raw material enters an external circulating type conveying bed reduction furnace of an external separator, reacts with gas sulfur in 2 seconds under the carrying of high-temperature flue gas from a rotary kiln, and the sulfur and the raw material
Figure BDA0002496880820000211
The mol ratio of the sulfur to the sulfur is 0.1:1, the temperature in the furnace is 700 ℃, and the calcium sulfide (CaS) and the undecomposed raw material in the raw material discharged from the reduction furnace
Figure BDA0002496880820000212
In a molar ratio of 0.10: 1; after the raw material leaves the reduction furnace with the flue gas, the raw material enters a cyclone separator to complete gas-solid separation, the flue gas enters a multi-stage suspension preheating system, and the pre-reduced raw material with the temperature of 700 ℃ enters a rotary kiln. The outlet temperature of the topmost cyclone preheater was 200 ℃.
D. Deep reduction and clinker sintering
The pre-reduced raw material enters a reduction rotary kiln through a blanking pipe, and the CaS in the raw material are controlled to be lower than 2 percent under the condition that the oxygen content in the flue gas at the outlet of the rotary kiln is controlled to be lower than
Figure BDA0002496880820000213
Oxidation reduction reaction is carried out in the kiln at 950 ℃, the reduction time of the materials in the kiln is 30min, and 85 percent of S element is SO2The other elements enter the smoke in the kiln in a form of primary solid-phase reaction; and (3) sintering the deeply reduced material in a sintering rotary kiln at 1100-1250 ℃ to form high-calcium sulphoaluminate cement clinker, wherein the sintering time of the material is 50 min.
The sintering fuel is sulfur-containing coal.
E. Clinker cooling, heat recycling and purification for producing sulfuric acid
The high-temperature clinker discharged from the sintering rotary kiln enters a cooler to exchange heat with air and be cooled to (room temperature +65) DEG C, part of the high-temperature air discharged from the cooler enters the rotary kiln to be used as combustion-supporting air of fuel, part of the high-temperature air enters a combustion chamber of a reduction furnace and an outlet combustion chamber of a cyclone separator to be used as combustion-supporting air of partial sulfur combustion, and the rest part of the high-temperature clinker is used as a drying heat source for drying gypsum and other raw materials;
and (3) after waste heat recovery and dust removal, the sulfur-containing flue gas out of the first-stage cyclone preheater enters a subsequent conventional sulfuric acid production process for washing, purifying, drying, converting, absorbing, recovering medium-low temperature waste heat and finally treating tail gas to prepare an industrial sulfuric acid product.
The chemical components of the clinker and the mineral composition of the clinker measured by the XRD diffraction quantitative analysis method in this example are shown in tables 20 and 21, respectively.
TABLE 20 chamotte chemical composition
Figure BDA0002496880820000221
TABLE 21 mineral phase composition of clinker
Figure BDA0002496880820000222
F. Preparation of cement
Cooling clinker from step E cooler, adding gypsum and groupMixing the materials, and then performing subsequent grinding to obtain high-calcium sulphoaluminate cement products with different performance requirements, wherein the fineness of the products is obtained by grinding the materials until the specific surface area is 360m2/kg。
Example 8
Referring to fig. 9, a method for producing sulphoaluminate cement and co-producing sulphuric acid by reducing gypsum-containing raw meal with sulphur gas comprises the following steps:
A. preparation of gaseous sulfur
Solid or liquid sulfur is led into a sulfur melting tank and is indirectly heated to 160 ℃ by steam or heat conduction oil or electricity to be melted into crude sulfur liquid, the crude sulfur liquid is filtered by a sulfur filter to obtain refined sulfur liquid, the refined sulfur liquid is conveyed into a gasification furnace after being metered by a conveying pump and heated and gasified to 900 ℃ to obtain high-temperature gas sulfur, and the gas sulfur is conveyed into a reduction furnace by a Venturi ejector.
B. Drying, grinding and batching
The industrial by-product gypsum is placed in a conveying bed drying furnace to be dried and dehydrated at 300 ℃, the bauxite, the siliceous correcting material and the iron correcting material are dried, ground and primarily mixed in a mill, and a drying heat source is high-temperature surplus air discharged by a cooler (an optional grate cooler) and a heat source obtained by recovering low-temperature waste heat in co-production sulfuric acid; mixing and homogenizing the dehydrated gypsum, bauxite, siliceous correcting material and iron correcting material in a mixer, and further homogenizing in a homogenizing warehouse to obtain raw material with uniform components. The mixture ratio of the dehydrated gypsum, bauxite, siliceous correcting material and iron correcting material is calculated according to three values of alkalinity coefficient (C), aluminum-sulfur ratio (P) and aluminum-silicon ratio (N) which are usually required by the sulphoaluminate cement clinker process, and the values are used for adjusting the proportion of sulphoaluminate raw material and controlling the components of the sulphoaluminate cement clinker to produce different varieties of high-iron sulphoaluminate cement clinker.
In the embodiment, phosphogypsum, coal gangue, bauxite, red mud, clay, iron slag and fly ash are used as raw materials, the raw materials are dried and ground into powder of more than 95-80 μm, most of the fly ash generated by burning calcined fuel coal enters clinker, and the chemical components of the fly ash are shown in Table 22.
TABLE 22 chemical composition of the raw materials and raw meal
Item CaO SiO2 Al2O3 Fe2O3 MgO P2O5 Na2O SO3 LOSS Total up to
Phosphogypsum 36.76 1.98 0.59 0.18 0.26 0.96 0.23 52.68 6.15 99.79
Coal gangue 21.82 30.15 16.56 3.45 0.71 0.09 0.00 11.95 15.27 100.00
Bauxite ore 2.30 2.23 71.41 11.57 0.07 0.00 0.12 0.16 16.82 99.68
Red mud 11.47 20.35 23.37 15.84 0.08 0.00 4.11 1.26 15.52 92.00
Clay clay 0.45 22.00 60.00 2.80 0.00 0.09 0.00 0.54 12.00 97.88
Iron slag 29.45 12.35 2.95 53.36 0.00 0.00 0.00 0.53 1.32 99.96
Coal ash 1.48 43.50 35.38 1.92 0.70 0.00 0.33 0.68 14.77 98.76
Raw material 28.31 6.61 14.80 3.23 0.28 0.68 0.23 37.66 8.21 100.00
The main raw materials comprise the following ingredients in parts by weight: 69.2 parts of phosphogypsum, 8.2 parts of coal gangue, 14.9 parts of bauxite, 1.0 part of red mud, 1.5 parts of iron slag, 1.0 part of clay and 4.1 parts of fly ash; the bauxite Al2O3The mass fraction is 71.41%, and the phosphogypsum is phosphogypsum hemihydrate.
C. Pre-heating pre-reduction
B, metering the raw materials from the step B, feeding the raw materials into a topmost cyclone preheater of a 6-stage suspension preheating system, rapidly completing gas-solid heat exchange and separation with hot air flow from a reduction furnace in the cyclone preheater, and sequentially completing step preheating within 60 seconds through lower-stage cyclone preheaters; the preheated raw material enters an external circulating type conveying bed reduction furnace of an external separator, reacts with gas sulfur in 45 seconds under the carrying of high-temperature flue gas from a rotary kiln, and the sulfur and the raw material
Figure BDA0002496880820000242
The mol ratio of the sulfur to the sulfur is 0.7:1, the temperature in the furnace is 980 ℃, and the calcium sulfide (CaS) and the undecomposed raw materials in the raw materials discharged from the reduction furnace
Figure BDA0002496880820000243
In a molar ratio of 0.35: 1; after the raw materials leave the reduction furnace with the flue gas, the raw materials enter a cyclone separator to complete gas-solid separation, and the flue gas enters a multi-stage suspension preheating systemAnd the pre-reduced raw material with the temperature of 950 ℃ enters the rotary kiln. The outlet temperature of the topmost cyclone preheater is 400 ℃, and the oxygen content in the flue gas at the outlet of the topmost cyclone preheater is detected to be 0.3-1.5% (v/v).
D. Deep reduction and clinker sintering
The pre-reduced raw material enters the rotary kiln through a blanking pipe, and the CaS in the raw material are mixed under the condition that the oxygen content in the smoke gas at the outlet of the rotary kiln is controlled to be less than 2 percent
Figure BDA0002496880820000244
Carrying out oxidation reduction reaction at 1150 ℃ in a kiln, wherein the reduction time of the material in the kiln is 10-30 min, and S element is SO2The other elements enter the smoke in the kiln in a form of primary solid-phase reaction; sintering the deeply reduced materials at 1300 ℃ to form the high-iron sulphoaluminate cement clinker, wherein the sintering time of the materials is 20 min.
E. Clinker cooling, heat recycling and purification for producing sulfuric acid
The high-temperature clinker discharged from the rotary kiln enters a grate cooler to exchange heat with air and be cooled to (room temperature +65) DEG C, part of the high-temperature air discharged from the cooler enters the rotary kiln to be used as combustion-supporting air of fuel, part of the high-temperature air enters a combustion chamber of a reduction furnace and an outlet combustion chamber of a cyclone separator to be used as combustion-supporting air of partial sulfur combustion, and the rest part of the high-temperature air is used as a drying heat source for drying gypsum and other raw materials;
and (3) after waste heat recovery and dust removal, the sulfur-containing flue gas out of the first-stage cyclone preheater enters a subsequent conventional sulfuric acid production procedure for washing, purifying, drying, converting, absorbing and finally carrying out tail gas treatment through medium-low temperature waste heat recovery to prepare an industrial sulfuric acid product.
The chemical components of the clinker and the mineral composition of the clinker measured by the XRD diffraction quantitative analysis method in this example are shown in tables 23 and 24, respectively.
TABLE 23 chamotte chemical composition
Figure BDA0002496880820000241
TABLE 24 chamotte mineral phase composition
Figure BDA0002496880820000251
F. Preparation of cement
Cooling the clinker from the cooler in the step E, adding gypsum and combined materials, and then performing subsequent grinding processing to obtain high-iron sulphoaluminate cement products with different performance requirements, wherein the fineness of the products is obtained by grinding the materials until the specific surface area is 320m2/kg。
The contents and scope of the present invention are not limited to the above-described embodiments, and those skilled in the art can derive other embodiments within the technical teaching of the present invention, but these embodiments should be included in the technical scope of the present invention.
The present invention provides a method for preparing sulphoaluminate cement and CO-producing sulfuric acid by using sulfur gas as reducing agent and reducing and decomposing gypsum and cement clinker, and does not use other reducing agent, such as solid coke, active carbon, anthracite or gas CO and H2And the like, other calcareous raw materials are not used, SO that the resource maximum utilization of industrial waste residue gypsum, bauxite, coal gangue, red mud, fly ash and the like is formed, the obtained raw materials have wide sources, the carbon emission is reduced, and the SO of the furnace gas is improved2The gas concentration, the equipment production efficiency improvement, the energy consumption and the production cost reduction and other social benefits and enterprise economic benefits.

Claims (10)

1. A method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas is characterized by comprising the following steps:
A. preparation of gaseous sulfur
Introducing solid or liquid sulfur into a sulfur melting tank, heating to 120-160 ℃ to melt into crude sulfur liquid, filtering by a sulfur filter to obtain refined sulfur liquid, sending into a gasification furnace, heating and gasifying to 450-900 ℃ to obtain high-temperature gas sulfur, and sending the gas sulfur into a reduction furnace by a Venturi ejector;
B. ingredients
Mixing the dehydrated gypsum and the ingredients in a blender mixer for homogenization, and further homogenizing in a homogenization siloHomogenizing to obtain raw materials with uniform components; the proportion of the dehydrated gypsum and the ingredients for preparing the raw material is determined by controlling the alkalinity coefficient (C), the aluminum-sulfur ratio (P) and the aluminum-silicon ratio (N) according to the application requirements of the sulphoaluminate cement clinker, the raw material has the value of 0.96-0.98 of the alkalinity coefficient C, 3.7-3.82 of the aluminum-sulfur ratio P and 3.0-3.2 of the aluminum-silicon ratio N, and the raw material comprises 65-90 parts of gypsum, 0-35 parts of bauxite, 0-15 parts of fly ash, 0-30 parts of coal gangue, 0-10 parts of red mud, 0-8 parts of iron slag and 0-20 parts of clay by weight, wherein the gypsum is dihydrate gypsum or hemihydrate gypsum; al in the bauxite2O3The mass fraction is 40-75%;
C. pre-heating pre-reduction
The raw materials are sent into a multi-stage suspension preheating system for step preheating, the preheated raw materials enter a reduction furnace to perform reduction reaction with sulfur gas entering the reduction furnace in the step A, the reacted materials enter a cyclone separator to complete gas-solid separation, the flue gas enters the multi-stage suspension preheating system, and the pre-reduced raw materials enter a rotary kiln; the reduction reaction in the reduction furnace is as follows: the preheated raw material enters a reduction furnace and is subjected to reduction reaction with gaseous sulfur under the carrying of high-temperature flue gas, and the reduction reaction conditions are as follows: (1) the molar ratio of sulfur entering the reduction furnace to sulfur in calcium sulfate in the raw material is (0.1-0.7): 1, (2) the molar ratio of calcium sulfide to CaSO in the raw material discharged from the reduction furnace4The molar ratio of (0.10-0.35) to (1), (3) the temperature in the reduction furnace is 700-980 ℃, and (4) the reduction reaction time is 2-45 seconds;
D. deep reduction and clinker sintering
Under the weak oxidizing atmosphere, the weak oxidizing atmosphere is as follows: controlling the oxygen content in the flue gas at the outlet of the rotary kiln to be less than 2% v/v, carrying out deep reduction reaction on the pre-reduced raw material in the rotary kiln, and sintering the deep-reduced raw material at high temperature to form sulphoaluminate cement clinker; the deep reduction reaction is to pre-reduce calcium sulfide and CaSO in the raw material4Carrying out oxidation reduction reaction in a rotary kiln at 950-1150 ℃, wherein the reduction time is 5-30 min, and 60-90% of S element is SO2The other elements are subjected to preliminary solid-phase reaction in the flue gas in the rotary kiln; the temperature of the material after deep reduction is950-1150 ℃, the high-temperature sintering temperature is 1100-1300 ℃, and the sintering time is 20-60 min;
E. clinker cooling, heat recycling and purification for producing sulfuric acid
The high-temperature cement clinker out of the rotary kiln enters a cooler to exchange heat with cooling air, the heat is recovered, and the sulfur-containing flue gas out of a first-stage cyclone preheater in the multi-stage suspension preheating system enters a subsequent conventional sulfuric acid production procedure to prepare an industrial sulfuric acid product after waste heat recovery and dust removal;
F. preparation of cement
The cement clinker from the cooler in the step E consists of minerals
Figure FDA0003458689190000021
C2S:8～60％，C4AF:3～35％，C3S:0～50％，
Figure FDA0003458689190000022
And (3) the other: 0 to 5 percent; gypsum and composite materials are added, and then the sulphoaluminate cement products with different performance requirements are obtained through subsequent grinding processing.
2. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas according to claim 1, wherein the dehydrated gypsum in the step B is gypsum obtained by drying and dehydrating industrial by-product gypsum in a conveying bed drying furnace at 120-300 ℃;
the ingredients are dried, ground and primarily mixed in a mill, and the drying heat source is the high-temperature surplus air discharged by a cooler, the flue gas waste heat recovery at the outlet of the primary cyclone preheater and the heat source obtained by the low-temperature waste heat recovery in the co-production of sulfuric acid.
3. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by using sulphur gas to reduce gypsum according to claim 2, wherein the industrial by-product gypsum is a calcium and sulfur material containing calcium sulfate, and comprises at least one or a mixture of phosphogypsum, desulfurized gypsum, salt gypsum, titanium dioxide by-product gypsum, fluorgypsum, nickel gypsum and manganese gypsum.
4. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by using sulfur gas to reduce gypsum according to claim 3, wherein the industrial byproduct gypsum is phosphogypsum or desulfurized gypsum.
5. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas according to claim 1, wherein the number of stages of the cyclone preheater of the multistage suspension preheating system in the step C is 4-6, the group of the cyclone preheater is single-row or double-row, and the material flow is single-row series or two-row cross series;
the step preheating is as follows: raw materials enter a first-stage cyclone preheater at the topmost layer of the multistage suspension preheating system, gas-solid mass transfer, heat exchange and separation are rapidly completed in the cyclone preheater together with hot air flow, and then stepped mass transfer, preheating and separation are completed within 20-60 seconds after the raw materials pass through the cyclone preheaters at the lower layers in sequence;
and the flue gas separated by the cyclone separator enters a multistage suspension preheater, and the separated solid material is pre-reduced raw material at 700-950 ℃.
6. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum through sulphur gas according to claim 1 or 5, wherein the reduction furnace in the step C is a gas-solid co-flow type conveying bed reduction reaction furnace which is a single-pass type conveying bed reactor or an external circulation type conveying bed reactor with an external separator;
b, arranging a combustion chamber at the bottom of the reduction furnace, wherein fuel of the combustion chamber is one or the combination of two of the liquid sulfur and the gas sulfur from the step A, the combustion chamber supplies heat required by the calcium sulfate prereduction, the high-temperature flue gas out of the rotary kiln enters the reduction furnace through the combustion chamber, and the rest of the high-temperature flue gas directly enters the reduction furnace through a bypass; part of the oxygen required by the combustion chamber comes from the oxygen brought by the flue gas of the rotary kiln, and the other part passes through the hot air discharged by the supplementary cooler.
7. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas as claimed in claim 1 or 5, wherein the outlet flue of the cyclone separator in step C is provided with an oxygen-supplementing combustion chamber, the supplementing air is used for consuming the residual sulfur in the flue gas, the amount of air supplemented into the combustion chamber is adjusted and controlled by detecting and controlling the oxygen content in the flue gas at the outlet of the topmost cyclone preheater to be 0-1.5% (v/v), so as to ensure that the tail gas at the outlet of the topmost cyclone preheater does not contain elemental sulfur, the air supplemented into the combustion chamber adopts hot air discharged by a cooler, and the temperature of the flue gas at the outlet of the topmost cyclone preheater is controlled to be 200-400 ℃.
8. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by using sulfur gas to reduce gypsum as claimed in claim 1, wherein the deep reduction and clinker sintering of step D are performed in one rotary kiln or in two rotary kilns connected in series in sections;
when a rotary kiln is adopted, the method comprises the following specific steps: firstly, the pre-reduced raw material enters a rotary kiln through a discharge pipe of a cyclone separator, and calcium sulfide and CaSO in the pre-reduced raw material4Finishing oxidation-reduction reaction in a rotary kiln, wherein the temperature in the rotary kiln at the reaction section is 950-1150 ℃, and the reaction time of materials in the rotary kiln is 5-30 min; then, the mixture enters a sintering section, sintering of the sulphoaluminate clinker is completed along with the rise of the temperature in the kiln and the prolonging of the residence time, the temperature in the kiln of the sintering section is 1100-1300 ℃, the material is sintered and stays in the kiln for 20-60 min, the kiln entering air consists of coal feeding air and high-temperature air which is discharged from a cooling machine, and the oxygen content in the kiln tail flue gas is controlled to be 0-1.5% v/v weak oxidation atmosphere; the temperature of flue gas entering a combustion chamber of a reduction furnace of the rotary kiln is 900-1100 ℃;
when two rotary kilns are connected in series, deep reduction and sintering are respectively completed in a reduction rotary kiln and a sintering rotary kiln, and the method comprises the following specific steps: the pre-reduced raw material enters a reduction rotary kiln through a discharge pipe of a cyclone separator, and calcium sulfide and CaSO in the raw material4The redox reaction is finished in a reduction rotary kiln, the temperature in the kiln is 950-1150 ℃, and the retention time is 5-30 minThe kiln inlet air consists of coal feeding air and tail gas of the sintering rotary kiln, reducing materials which are discharged from the reduction rotary kiln at 950-1150 ℃ enter the sintering rotary kiln through a discharging pipe to finish sintering of sulphoaluminate clinker, the temperature in the sintering rotary kiln is 1100-1300 ℃, the materials stay in the sintering rotary kiln for 20-60 min, the kiln inlet air consists of coal feeding air and high-temperature air discharged from a cooler, and the oxygen content in flue gas at the outlet of the sintering rotary kiln is controlled to be 2-10% of oxidizing atmosphere; the temperature of flue gas entering the reduction rotary kiln through the sintering rotary kiln is 1000-1200 ℃, the oxygen content in the flue gas at the outlet of the reduction rotary kiln is controlled to be 0-1.5% of weak oxidation atmosphere, and the temperature of flue gas entering a combustion chamber of the reduction rotary kiln is 900-1100 ℃.
9. The method for preparing sulphoaluminate cement and co-producing sulfuric acid by using sulphur gas to reduce gypsum according to claim 1, wherein the high-temperature cement clinker from the rotary kiln in the step E is cooled to room temperature-65 ℃ by heat exchange with air in a cooler;
ways to recover heat include: part of the high-temperature air out of the cooler enters the rotary kiln to be used as combustion-supporting air of fuel, part of the high-temperature air enters a combustion chamber of the reduction furnace and an outlet combustion chamber of the cyclone separator to be used as combustion-supporting air of partial sulfur combustion, and the rest part of the high-temperature air is used as a drying heat source of gypsum drying and other raw materials;
after waste heat recovery and dust removal, the sulfur-containing flue gas out of the first-stage cyclone preheater enters a subsequent conventional sulfuric acid production procedure for washing, purifying, drying, converting, absorbing, recovering middle-low temperature waste heat and finally treating tail gas to prepare an industrial sulfuric acid product;
the cooler is one of a grate cooler, a roller cooler and a vertical cooler.
10. The method for preparing sulphoaluminate cement and co-producing sulphuric acid by using sulphur gas to reduce gypsum according to claim 1, wherein the step F is carried out
According to the content of high-temperature sintered gypsum in cement clinker, combining test and calculation to define that no gypsum or less gypsum and composite material are added, then making subsequent grinding treatment so as to obtain the invented productThe performance requirement of the mud product is that the fineness of the product is ground to 320-420 m of specific surface area2/kg；
The sulphoaluminate cement product comprises ordinary sulphoaluminate cement, high-iron sulphoaluminate cement, high-silicon sulphoaluminate cement and high-calcium sulphoaluminate cement.
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