CN111574080B - Method for preparing belite sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum with sulfur gas - Google Patents

Abstract

The invention relates to a method for co-producing sulfuric acid by reducing gypsum with sulfur gas to produce Belite sulfoaluminate cement. Control the alkalinity coefficient (C), aluminum-sulfur ratio (P) and aluminum-silicon ratio (N), and select one or more of low-grade bauxite, fly ash, coal gangue, red mud, clay, and iron slag As an ingredient, gaseous sulfur is used as a reducing agent to promote the decomposition of gypsum to obtain Belite sulfoaluminate cement, and at the same time, a high concentration of gas _- phase SO2 flue gas is obtained, which is used for subsequent flue gas production of sulfuric acid. Compared with the prior art, the method of the invention can not only consume a large amount of industrial gypsum, but also save limestone and natural gypsum resources, and at the same time, high-quality Belite sulfoaluminate cement and industrial sulfuric acid products can be obtained, with simple process and system control indicators. It has strong implementability, convenient operation and management, advanced process equipment, low equipment investment, low energy consumption, low operation cost and high degree of automation.

Description

Method for co-producing sulfuric acid by reducing gypsum with sulfur gas to make Belite sulfoaluminate cement

technical field

The invention relates to building materials and chemical products, in particular to a method for co-producing sulfuric acid by reducing gypsum-containing raw meal with sulfur gas to prepare Belite sulfoaluminate cement.

Background technique

硅酸二钙(C₂S)为主要矿物相组成，再掺入少量石膏并经研磨获得硫铝酸盐水泥产品。与普通硅酸盐水泥相比，由于原料石灰石用量降低、烧成温度也比硅酸盐水泥1300～1450℃要低100～150℃，因此，在能耗和CO₂排放方面也具有明显优势。但是，现有传统硫铝酸盐生产因对含铝质原材料Al₂O₃含量(大于60％)的要求相对较高，不仅增加了原料成本，而且原料来源及取材范围也受到限制，导致国内硫铝酸盐水泥的年产量并不高，该系列水泥的应用也受到了一定程度的影响，传统硫铝酸盐水泥的产量无法满足市场和工程需要，另外以石灰石为钙源也增加了CO₂排放；如何提高硫铝酸盐水泥原料的适应性、减少排放、降低能耗和原料成本已成为业内外科研人员研究的重点。Sulfoaluminate cement has the advantages of low alkalinity, high early strength, micro-expansion, good corrosion resistance and frost resistance, and is especially suitable for coastal and cold areas and emergency repair projects. Traditional sulfoaluminate cement is made of calcium sulfoaluminate by calcining limestone, bauxite and gypsum at high temperature (1200-1350 ℃).

Dicalcium silicate (C ₂ S) is the main mineral phase composition, and then a small amount of gypsum is added and ground to obtain a sulfoaluminate cement product. Compared with ordinary Portland cement, because the amount of raw limestone is reduced and the firing temperature is 100-150°C lower than that of Portland cement (1300-1450°C), it also has obvious advantages in energy consumption and CO ₂ emissions. However, the existing traditional sulfoaluminate production requires relatively high Al ₂ O ₃ content (greater than 60%) of aluminum-containing raw materials, which not only increases the cost of raw materials, but also limits the source of raw materials and the range of materials that can be obtained. The annual output of sulfoaluminate cement is not high, and the application of this series of cement has also been affected to a certain extent. The output of traditional sulfoaluminate cement cannot meet the needs of the market and engineering. In addition, using limestone as calcium source also increases CO ₂ Emissions; how to improve the adaptability of sulfoaluminate cement raw materials, reduce emissions, reduce energy consumption and raw material costs has become the focus of research by researchers inside and outside the industry.

是在硫铝酸盐矿物的基础上发展而来的，通过大幅度降低铝酸盐相含量，提高硅酸盐相含量，从而形成一种新的矿物相组成；该矿物相改变后的水泥熟料，其铝质原料不再局限于品质单一价格高的铝矾土原料，可以使用来源广泛价格低廉的煤矸石、高铝粉煤灰、低品位铝矾土、铝土尾矿、含铝岩石等铝含量相对较低的原料。硅酸盐相的大幅度增加，能很好地解决硫铝酸盐水泥长期强度增长率偏低的问题，使熟料的性能向硅酸盐水泥熟料接近，既有硫铝酸盐水泥的早期强度，又具有硅酸盐水泥的后期强度。原材料取材范围的扩大和性能的改进，制造成本的显著下降，使得贝利特-硫铝酸盐水泥必将突破特种用途水泥的范畴，应用范围相对硫铝酸盐水泥更为广泛和普遍，在更多的应用领域替代硅酸盐水泥，成为除硅酸盐水泥之外，另一具有普遍应用性能的新的水泥品种。但贝利特硫铝酸盐水泥还没有国家标准，在生产工艺和产品性能还处于研究开发阶段，如何有效利用工业石膏、低品位铝土矿、煤矸石、粉煤灰等工业废渣生产贝利特硫铝酸盐水泥成为国内科技人员关注的重点。The main mineral phases of Belite-sulfoaluminate cement are dicalcium silicate (C ₂ S) and tetracalcium sulfoaluminate

It is developed on the basis of sulfoaluminate minerals. By greatly reducing the content of aluminate phase and increasing the content of silicate phase, a new mineral phase composition is formed; Its aluminum raw materials are no longer limited to bauxite raw materials with a single quality and high price, but can use coal gangue, high-alumina fly ash, low-grade bauxite, bauxite tailings, and aluminum-bearing rocks from a wide range of sources and low prices. raw materials with relatively low aluminum content. The large increase of the silicate phase can well solve the problem of the low long-term strength growth rate of sulfoaluminate cement, making the performance of clinker close to that of Portland cement clinker. Early strength, but also has the late strength of Portland cement. The expansion of the range of raw materials, the improvement of performance, and the significant reduction in manufacturing costs make Belite-sulfoaluminate cement bound to break through the category of special-purpose cement, and its application range is more extensive and common than sulfoaluminate cement. More application fields replace Portland cement and become another new type of cement with universal application performance in addition to Portland cement. However, there is no national standard for Belite sulfoaluminate cement, and the production process and product performance are still in the research and development stage. How to effectively use industrial waste such as industrial gypsum, low-grade bauxite, coal gangue, fly ash and other industrial waste to produce Beili Special sulfoaluminate cement has become the focus of domestic scientific and technological personnel.

Existing chemical industry production and flue gas desulfurization produce a large amount of process gypsum waste residue, of which desulfurization gypsum and phosphogypsum account for more than 85% of the industrial by-product gypsum. At present, the annual output of desulfurized gypsum in my country is about 80 million tons, and the comprehensive utilization rate is about 83%; the annual output of phosphogypsum is about 80 million tons, and the comprehensive utilization rate is less than 40%; other by-product gypsum is about 25 million tons, and the comprehensive utilization rate is about 40%. . At present, the stockpile of phosphogypsum is the largest among the industrial by-product gypsum, reaching more than 500 million tons. A large amount of industrial by-product gypsum is piled up, which not only occupies land, but also wastes resources. The acid and other harmful substances contained in it can easily pollute the surrounding environment. It has become an important factor restricting the sustainable development of coal-fired unit flue gas desulfurization and phosphate fertilizer enterprises in my country.

At present, the main application directions of my country's industrial by-product gypsum are cement retarder, external sales or external supply, gypsum board and gypsum block, road construction or filling, building gypsum powder, etc. Mainly used on a small scale. The research and application of comprehensive large-scale and high-efficiency utilization technology of industrial by-product gypsum is mainly concentrated in the field of gypsum decomposition, that is, "sulfur is used for sulfur and calcium is used for calcium", which can be roughly divided into two directions. The first is the research on the preparation of high value-added products by the decomposition of industrial by-product gypsum.

Gypsum decomposition methods include carbon reduction and sulfur reduction. The industrial by-product gypsum carbon reduction and firing of Portland cement clinker to co-produce sulfuric acid has been industrially applied. The gypsum raw material is mostly phosphogypsum. my country is represented by Luxi Chemical, Lubei Chemical, Guizhou Kingenta and other enterprises. There are 11 production lines, with an annual output of 800,000 tons of sulfuric acid and 1.2 million tons of cement. The largest single line is the 150,000-ton sulfuric acid + 200,000-ton Portland cement production line of Guizhou Kingenta. After more than 30 years of development, the technology of "third generation" carbon reduction to produce Portland cement clinker is relatively mature. The energy consumption of gypsum carbon reduction is high, the tail gas contains a large amount of CO ₂ , the concentration of SO ₂ in the tail gas is low, and the cost of acid production is high. The sulfur reduction method "substitutes carbon with sulfur" and uses sulfur instead of coke as a reducing agent, which has considerable energy saving and emission reduction benefits compared with the carbon reduction method.

(1000～1400℃、30min～180min)制得CaO固渣冷却后作为水泥熟料用于水泥生产；但该方法中气态硫磺摩尔分率低，气态硫磺与石膏的反应时间长，高温CaS需要在惰性气氛下冷却才能防止空气侵入对CaS的氧化，冷却后的CaS磨粉又要与石膏再次加热生产高温固渣CaO，CaO固渣冷却后再去按水泥配料生产水泥产品，多次加热冷却，工艺流程长且复杂，能耗高，工艺过程及热量组织不合理，也没有如何获得高温气态硫磺的具体方法，运行操作难度较高，工业化可实施性差。Chinese invention patent CN101708826A "A method for reducing and decomposing phosphogypsum with sulfur", the invention discloses the use of a multi-stage decomposition process to reduce phosphogypsum with gaseous sulfur, and finally obtain a CaO solid slag product for cement clinker production. The basic steps are: high temperature Preheat phosphogypsum with inert gas (500～900℃, 10～30min) → Pass gaseous sulfur with a molar fraction of 10～50% for reduction reaction with phosphogypsum (60～120min) → Grind CaS block after cooling Milling and mixing with phosphogypsum in molar ratio (1～1.5:3)→CaS high temperature reduction

(1000～1400℃, 30min～180min) the obtained CaO solid slag is cooled and used as cement clinker for cement production; but in this method, the mole fraction of gaseous sulfur is low, the reaction time of gaseous sulfur and gypsum is long, and high temperature CaS needs to be used in cement production. Cooling in an inert atmosphere can prevent the oxidation of CaS by air intrusion. The cooled CaS powder should be reheated with gypsum to produce high-temperature solid slag CaO. After the CaO solid slag is cooled, it will be used to produce cement products according to cement ingredients, and heated and cooled for many times. The technological process is long and complex, the energy consumption is high, the technological process and heat organization are unreasonable, and there is no specific method for obtaining high-temperature gaseous sulfur, the operation and operation are difficult, and the industrialization feasibility is poor.

的25～27％还原成为CaS，出炉物料送入回转窑中完成深度还原和熟料烧结，全系统由制备硫磺气体、生料配置和旋风预热、石膏还原、石膏还原产物制水泥熟料和尾气制酸构成；该方法是利用气体硫磺还原石膏生料制硫酸联产硅酸盐水泥熟料的方法，硅酸盐水泥熟料矿物相形成要求生料石膏中

近100％分解为CaO进入水泥熟料，而熟料中要求几乎不含CaS，需要控制工业石膏中的磷和氟含量，避免其对水泥性能的影响，对磷石膏通常需要预处理，工艺操作控制难度较高，产品质量波动较大。Chinese invention patent CN 104555946 B discloses a method for producing cement clinker with sulfuric acid by reducing gypsum gas with sulfur gas.

25-27% of the ore is reduced to CaS, and the discharged materials are sent to the rotary kiln to complete the deep reduction and clinker sintering. The method is to use gas sulfur to reduce gypsum raw meal to produce sulfuric acid to co-produce Portland cement clinker. The formation of the mineral phase of Portland cement clinker requires that the raw gypsum

Nearly 100% is decomposed into CaO into the cement clinker, and the clinker is required to contain almost no CaS. It is necessary to control the phosphorus and fluorine content in the industrial gypsum to avoid its influence on the performance of the cement. The phosphogypsum usually requires pretreatment, process operation The control difficulty is high, and the product quality fluctuates greatly.

中的

及少量高温烧结游离

石膏用量仅为10～30％；近年来，也有专利和文献报道采用工业石膏为原料经煅烧分解制取硫铝酸盐或贝利特硫铝酸盐水泥，石膏在矿物相中不仅用作熟料矿物相的无水硫铝酸钙

中的

及少量高温烧结游离

还可替代原料石灰石作为水泥熟料中CaO的来源，如此可以最大限度地提高原料石膏的使用量，石膏用量提高到70～85％，并可减少或避免由于不用或少用石灰石原料而带来的CO₂排放。硫铝酸盐水泥与硅酸盐水泥相比，除了居多水泥产品的优越性能外，还可使用更多的原料石膏，生料中石膏不需要像硅酸盐水泥那样要求～100％分解，其中原料石膏仅需要分解60～90％转化为CaO，其它以

和游离

的形式保留在熟料矿物相中，资源化利用工业石膏制硫铝酸盐或贝利特硫铝酸盐水泥比制硅酸盐水泥其优势更为显著。但是，如何解决石膏的有效分解问题，气相中SO₂能否得到足够高的浓度，能否满足联产硫酸需要的气浓要求，是否需要对气相中的SO₂进行另外的脱硫处理来满足环保要求，都困扰着相关技术的应用和发展。刘娜等在实验室中将活性炭与磷石膏按C/S＝3配料，在CO₂气氛950℃下煅烧1h，然后切换到空气气氛1000℃下煅烧1h，再升温到1200℃煅烧30min，获得磷石膏的分解率91.5％，磷石膏的分解产物为CaO，不含CaS，烧成熟料矿物相及性能达到了贝利特-硫铝酸盐水泥熟料指标要求。中国发明专利CN106630701.B、CN106630702.B、CN106603703.B、CN106431030.B、CN106431031.B、CN106365476.B、CN106365477.B、CN106365478.B等公开了采用磷石膏或脱硫石膏完全代替石灰石和天然石膏，再辅以铝矾土、铁渣和/或硅石、无烟煤为原料按一定比例配置成水泥生料，然后以碳还原经分段或直接煅烧制取硫铝酸盐水泥熟料，煅烧尾气联产硫酸。中国发明专利申请号CN201810964708.7“一种磷石膏煅烧贝利特硫铝酸盐水泥熟料的方法及水泥熟料”，该发明公开了配料时按75～80％磷石膏、10～15％铝质原料、10～15％硅质原料配比混合均匀，首先在1000～1100℃预热并进行脱硫160～180分钟，然后再在1320～1350℃煅烧60～80分钟形成水泥熟料矿物。上述发明方法目的都是最大限度地利用了工业副产石膏作为钙质和硫质原料，为工业副产石膏的资源化利用提供了很好设想，工艺上能打通；但以上方法大都采用活性炭或固体焦炭或无烟煤作为固体还原剂，将石膏、粘土、高品质铝矾土、粉煤灰、铁渣、高硫煤等一起配料煅烧生产硫铝酸盐或贝利特硫铝酸盐水泥熟料，碳还原总体上投资能耗高、高CO₂排放、炉气SO₂浓度偏低、联产硫酸“二转二吸”困难、运行成本高，存在运行操作、环保和经济成本方面的问题。The research on the large-scale decomposition of industrial by-product gypsum to prepare high value-added products is mainly divided into two aspects, one is calcium oxide as a product, the other is cement clinker as a product, the above-mentioned Luxi Chemical, Lubei Chemical, Guizhou Jinzheng University and other enterprises use the carbon reduction method to burn Portland cement clinker. The above-mentioned CN101708826A patented product is the sulfur-reduced gypsum-made solid slag CaO, and the above-mentioned CN 104555946 B patented product is the sulfur-reduced gypsum-made Portland cement clinker. . In recent years, domestic scholars have carried out a lot of research work on the use of gypsum to produce sulfoaluminate or Belite sulfoaluminate cement: in the early production of sulfoaluminate cement, most of the raw material gypsum used natural gypsum. Industrial gypsum such as phosphogypsum or desulfurized gypsum replace natural gypsum to produce sulfoaluminate or Belitt sulfoaluminate cement, but in these technologies gypsum is mainly used as anhydrous calcium sulfoaluminate in the fired mineral phase

middle

and a small amount of high temperature sintering free

The amount of gypsum is only 10-30%; in recent years, there are also patents and literature reports using industrial gypsum as raw material to produce sulfoaluminate or Belite sulfoaluminate cement by calcining and decomposing. Anhydrous calcium sulfoaluminate

middle

and a small amount of high temperature sintering free

It can also replace raw limestone as the source of CaO in cement clinker, which can maximize the use of raw gypsum, increase the amount of gypsum to 70-85%, and reduce or avoid the use of limestone raw materials. of CO ₂ emissions. Compared with Portland cement, sulfoaluminate cement can use more raw material gypsum in addition to the superior performance of most cement products. Gypsum in raw meal does not require ~100% decomposition like Portland cement. The raw gypsum only needs to be decomposed 60-90% into CaO, and the other

and free

The form of sulfoaluminate is retained in the clinker mineral phase, and the resource utilization of industrial gypsum to make sulfoaluminate or Belite sulfoaluminate cement has more significant advantages than portland cement. However, how to solve the problem of effective decomposition of gypsum, whether the SO ₂ in the gas phase can obtain a high enough concentration, whether it can meet the gas concentration requirements for co-production of sulfuric acid, and whether it is necessary to perform additional desulfurization treatment on the SO ₂ in the gas phase to meet environmental protection requirements The requirements are all perplexing the application and development of related technologies. In the laboratory, Liu Na et al. mixed activated carbon and phosphogypsum according to C/S=3, calcined at 950 °C in a _CO2 atmosphere for 1 h, then switched to an air atmosphere at 1000 °C for 1 h, and then heated up to 1200 °C for 30 min. The decomposition rate of phosphogypsum is 91.5%, and the decomposition product of phosphogypsum is CaO, which does not contain CaS. The mineral phase and performance of the fired clinker meet the requirements of the Belite-sulfoaluminate cement clinker. Chinese invention patents CN106630701.B, CN106630702.B, CN106603703.B, CN106431030.B, CN106431031.B, CN106365476.B, CN106365477.B, CN106365478.B, etc. disclose the use of phosphogypsum or desulfurized gypsum to completely replace limestone and natural gypsum, It is then supplemented by bauxite, iron slag and/or silica and anthracite as raw materials to prepare cement raw meal in a certain proportion, and then carbon reduction is used to obtain sulfoaluminate cement clinker by segmental or direct calcination, and the calcined tail gas is co-produced. sulfuric acid. Chinese invention patent application number CN201810964708.7 "a method for calcining Belitt sulfoaluminate cement clinker and cement clinker with phosphogypsum", the invention discloses that the proportion of 75-80% phosphogypsum, 10-15% Aluminium raw material and 10-15% siliceous raw material are mixed evenly in proportion, firstly preheat at 1000-1100 ℃ and desulfurize for 160-180 minutes, and then calcinate at 1320-1350 ℃ for 60-80 minutes to form cement clinker minerals. The purpose of the above-mentioned invention method is to maximize the utilization of industrial by-product gypsum as calcareous and sulphurous raw materials, which provides a good idea for the resource utilization of industrial by-product gypsum, and the technology can be opened up; but most of the above methods use activated carbon or Solid coke or anthracite as solid reducing agent, calcining gypsum, clay, high-quality bauxite, fly ash, iron slag, high-sulfur coal, etc. together to produce sulfoaluminate or Belite sulfoaluminate cement clinker In general, carbon reduction has high investment and energy consumption, high CO ₂ emissions, low SO ₂ concentration in furnace gas, difficulty in co-producing sulfuric acid with "two rotations and two suctions", and high operating costs. There are problems in operation, environmental protection and economic costs.

There are also some patents or literature reports that industrial by-product gypsum such as phosphogypsum or desulfurized gypsum or titanium gypsum is used together with limestone as the source of calcium and sulfur in cement ingredients, and the cement raw meal required to be configured with other raw materials such as bauxite is processed. Calcination to produce sulfoaluminate cement clinker or Belite sulfoaluminate cement clinker, these methods use a small part of gypsum decomposition to replace a part of CaO in limestone, can not effectively use industrial waste gypsum gypsum, calcination The SO ₂ concentration in the flue gas also does not meet the concentration requirements of conventional industrial production of sulfuric acid, and the SO ₂ decomposed by gypsum also increases the burden of environmental protection.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a kind of method of sulfur gas reducing gypsum to make Belitt sulfoaluminate cement co-producing sulfuric acid in order to overcome the defect existing in the above-mentioned prior art, can solve the above-mentioned problems, obtain the high level of gypsum in the cement raw meal. Decomposition rate, completely replace CaO in limestone with CaO decomposed by gypsum, and use low-grade bauxite, coal gangue, fly ash as raw materials to meet the batching requirements of Belite sulfoaluminate cement, and use gas sulfur as reducing agent , so that the decomposition reaction of gypsum can be carried out quickly and efficiently, and a high concentration of gas-phase SO ₂ flue gas can be obtained, which provides the best process conditions for the subsequent co-production of sulfuric acid.

For the description of the present invention, unless otherwise stated, the following abbreviations are used to designate the mineral composition of cement:

C stands for CaO;

A represents Al ₂ O ₃ ;

F represents Fe ₂ O ₃ ;

S stands for SiO ₂ ;

代表SO₃；

stands for SO ₃ ;

代表CaSO₄；

represents CaSO ₄ ;

C ₂ S stands for Belite, that is, dicalcium silicate 2CaO·SiO ₂ ;

C ₃ S represents tricalcium silicate 3CaO·SiO ₂ ;

代表硫铝酸钙3CaO·3Al₂O₃·CaSO₄；

Represents calcium sulfoaluminate 3CaO·3Al ₂ O ₃ ·CaSO ₄ ;

C ₄ AF represents tetracalcium ferric aluminate 4CaO·Al ₂ O ₃ ·Fe ₂ O ₃ ;

The object of the present invention can be realized by the following technical solutions: a method for co-producing sulfuric acid by reducing gypsum-containing raw meal to produce Belite sulfoaluminate cement, the method takes industrial by-product gypsum as the main raw material, The application of Lit's sulfoaluminate cement clinker requires the selection of low-grade bauxite, fly ash, coal gangue, red One or more of mud, clay and iron slag are used as ingredients, and gaseous sulfur is used as a reducing agent to promote the decomposition of gypsum to obtain Belite sulfoaluminate cement, and at the same time obtain high-concentration gas-phase SO ₂ flue gas. Sulfuric acid is produced from the subsequent flue gas.

Specifically include the following steps:

A. Preparation of gaseous sulfur

The solid or liquid sulphur is introduced into the sulphur melting tank and indirectly heated to 120-160℃ by steam or heat transfer oil or electricity to melt into crude sulphur liquid, which is filtered by a sulphur filter to obtain refined sulphur liquid, which is then fed into the gas through a transfer pump and metered. The furnace is heated and gasified to 450-900℃ to obtain high-temperature gas sulfur, and the Venturi ejector sends the gas sulfur into the reduction furnace.

B. Drying, grinding and ingredients

The industrial by-product gypsum is placed in a conveying bed drying furnace for drying and dehydration at 120 to 300 °C, and the ingredients (including bauxite, siliceous correction material and iron correction material) are dried, ground and preliminarily mixed in a mill. The dry heat source is the high-temperature excess air discharged from the cooler, the heat source obtained from the waste heat recovery of the flue gas at the outlet of the first-stage cyclone preheater, and the heat source obtained from the low-temperature waste heat recovery from the co-production of sulfuric acid; dehydrated gypsum is mixed with bauxite, siliceous correction material and The iron calibration material is mixed and homogenized in a mixer, and further homogenized in a homogenization silo to obtain a raw meal with uniform composition. Dehydrated gypsum and bauxite, siliceous correction material and iron correction material according to the three rate values usually required by Belite sulfoaluminate cement clinker process: alkalinity coefficient (C), aluminum sulfur ratio (P), aluminum The silicon ratio (N) calculates the batching ratio, and uses these ratio values to adjust the ratio of Belite sulphoaluminate raw meal and control the composition of Belite sulphoaluminate cement clinker to produce different varieties of Belite sulphoaluminate Acid Cement Clinker.

Further, the ratio values of the cement raw meal are the alkalinity coefficient C: 0.92-0.98, the aluminum-sulfur ratio P: 0.95-3.85, and the aluminum-silicon ratio N: 0.45-3.20. To meet the above-mentioned ratios, the main raw materials in parts by weight are composed of: 70-95 parts of gypsum, 0-25 parts of bauxite, 0-15 parts of fly ash, 0-30 parts of coal gangue, 0-20 parts of clay, and red mud. 0-30 parts, iron slag 0-8 parts, the gypsum is dihydrate gypsum or hemihydrate gypsum; the bauxite is one of low-grade bauxite or high-grade bauxite, and its Al ₂ O _3. The mass fraction is 40-75%, preferably low-grade bauxite, and the Al ₂ O ₃ mass fraction is 40-55%.

为主要成分的钙质、硫质原料，包括磷石膏、脱硫石膏、盐石膏、钛石膏、氟石膏、镍石膏、锰石膏中的至少一种或几种混合物，含铝质、硅质、铁质原料为低品位铝土矿、高铝粉煤灰、煤矸石、赤泥、粘土、铁渣等至少一种或一种以上的混合物。Further, the industrial by-product gypsum is a kind of

Calcium and sulfur raw materials as main components, including at least one or several mixtures of phosphogypsum, desulfurization gypsum, salt gypsum, titanium gypsum, fluorine gypsum, nickel gypsum, and manganese gypsum, containing aluminum, siliceous, iron The high-quality raw materials are at least one or more mixtures of low-grade bauxite, high-alumina fly ash, coal gangue, red mud, clay, iron slag, etc.

C. Preheating and pre-reduction

中硫的摩尔比为(0.1～0.7):1，炉内温度700℃～980℃，出还原炉的生料中硫化钙(CaS)与未分解的

的摩尔比为(0.10～0.35):1；生料随烟气离开还原炉后，进入旋风分离器完成气固分离，烟气进入多级悬浮预热系统，温度为700～950℃的预还原生料进入回转窑。最顶层第一级旋风预热器出口温度为200～400℃。The raw meal from step B is metered and sent to the topmost first-stage cyclone preheater of the multi-stage suspension preheating system, and the hot air flow from the reduction furnace quickly completes the gas-solid transfer in the first-stage cyclone preheater. Mass transfer, heat exchange and separation, and then pass through the lower cyclone preheaters at all levels to complete the cascade mass transfer, preheating and separation within 20 to 60 seconds; the preheated raw meal enters the reduction furnace, and the raw meal from the rotary kiln Under the carrying of high temperature flue gas, it reacts with gas sulfur within 2 to 45 seconds.

The molar ratio of middle sulfur is (0.1～0.7):1, the temperature in the furnace is 700℃～980℃, and calcium sulfide (CaS) and undecomposed calcium sulfide (CaS) in the raw meal coming out of the reduction furnace.

The molar ratio is (0.10～0.35):1; after the raw meal leaves the reduction furnace with the flue gas, it enters the cyclone separator to complete the gas-solid separation, and the flue gas enters the multi-stage suspension preheating system, and the temperature is 700～950 ℃ of pre-reduction The raw meal enters the rotary kiln. The outlet temperature of the topmost first-stage cyclone preheater is 200-400°C.

Further, the number of preheater stages of the multi-stage suspension preheating system is 4 to 6, the cyclone preheater group is single-column or double-column, and the material flow is single-column serial or two-column cross-column.

的摩尔比为0.1～0.7:1；(4)还原炉出口固体产物中CaS与未反应的

的摩尔比为0.10～0.35:1；(5)顶级旋风预热器出口温度为250～400℃，烟气氧含量0.3～2.0％(v/v)，优选0.3～1.5％(v/v)。Further, the control conditions of the reduction reaction system in the reduction furnace: (1) the temperature in the reduction furnace is 700-980°C; (2) the reduction reaction time is 2-45 seconds; (3) the amount of sulfur added is the same as that in the raw meal

(4) CaS and unreacted CaS in the solid product at the outlet of the reduction furnace

(5) The outlet temperature of the top cyclone preheater is 250-400°C, and the oxygen content of the flue gas is 0.3-2.0% (v/v), preferably 0.3-1.5% (v/v) .

Further, the reduction furnace is a gas-solid co-flow conveyed bed reduction reaction furnace, which is a single-pass type conveyed bed reactor or an external circulation type conveyed bed reactor with an external separator.

预还原所需的热量，出回转窑的高温烟气部分通过燃烧室进入还原炉，其余部分走旁路直接进入还原炉，该燃烧室所需氧一部分来自回转窑尾气中带来的氧气，另一部分通过补充冷却机排出的热空气。Further, a combustion chamber is arranged at the bottom of the reduction furnace, and its fuel is one or a combination of two kinds of liquid sulfur or gas sulfur from A. A combustion chamber is set at the bottom of the reduction furnace, supplementary

For the heat required for pre-reduction, part of the high-temperature flue gas from the rotary kiln enters the reduction furnace through the combustion chamber, and the rest enters the reduction furnace directly through the bypass. A portion of the hot air exhausted through the supplemental cooler.

Further, the outlet flue of the cyclone separator at the outlet of the reduction furnace is set as a supplementary oxygen combustion chamber, and the supplementary air is used to consume the remaining gas sulfur in the flue gas of the reduction furnace. 0.3-1.5% (v/v) to adjust and control the amount of air that is supplemented into the combustion chamber to ensure that the cyclone preheater system is a weak oxidizing atmosphere and that the exhaust gas from the top preheater does not contain elemental sulfur, and the supplementary air to the combustion chamber is cooled hot air from the machine.

D. Deep reduction and clinker sintering

在窑内950～1150℃下发生氧化还原反应，物料在窑内还原时间为5～30min，60～90％的S元素以SO₂的形式进入窑内烟气中，其它元素发生初步的固相反应；深度还原之后的物料在1100～1300℃烧结并形成贝利特硫铝酸盐水泥熟料，物料的烧结时间为20～60min。The pre-reduced raw meal enters the rotary kiln through the feeding pipe, and the oxygen content in the flue gas at the outlet of the rotary kiln is controlled to be less than 2%.

Oxidation-reduction reaction occurs in the kiln at 950-1150 ℃, the reduction time of the material in the kiln is 5-30min, 60-90% of the S element enters the kiln flue gas in the form of SO ₂ , and other elements form a preliminary solid phase Reaction; the material after deep reduction is sintered at 1100-1300° C. to form Belite sulfoaluminate cement clinker, and the sintering time of the material is 20-60 minutes.

Sintered fuel includes one or a mixture of sulfur-containing coal, natural gas, fuel oil, coal gas, and liquefied petroleum gas.

Further, deep reduction and clinker sintering are completed in stages in one rotary kiln or two rotary kilns connected in series:

在窑内完成氧化还原反应，该反应段窑内温度950～1150℃，物料在窑内反应停留时间5～30min；然后进入烧结段，随着窑内温度升高和停留时间延长，完成贝利特硫铝酸盐熟料的烧结，该烧结段窑内温度1100～1300℃，物料在窑内停留时间20～60min，入窑风由送煤风和出冷却机的高温空气组成，窑烟气中含氧气含量控制在0～1.5％(v/v)弱氧化气氛；回转窑进入还原炉的烟气温度为900～1100℃。When a rotary kiln is used, the deep reduction of gypsum and the sintering of clinker are completed in a rotary kiln; first, the pre-reduced raw meal enters the rotary kiln through the feeding pipe of the cyclone separator, and the CaS in the raw meal and the

The redox reaction is completed in the kiln. The temperature in the kiln in this reaction section is 950-1150 °C, and the reaction residence time in the kiln is 5-30 minutes; then it enters the sintering section. For the sintering of special sulfoaluminate clinker, the temperature in the kiln in this sintering section is 1100-1300 °C, the material stays in the kiln for 20-60 minutes, the air entering the kiln is composed of coal supply air and high-temperature air exiting the cooler, and the kiln flue gas The oxygen content in the medium is controlled at 0-1.5% (v/v) weakly oxidizing atmosphere; the temperature of the flue gas entering the reduction furnace from the rotary kiln is 900-1100°C.

在还原窑内完成氧化还原反应，窑内温度950～1150℃，物料在还原窑内停留时间5～30min，入窑风由送煤风和烧结回转窑的尾气组成；出还原回转窑950～1150℃的还原料经下料管进入烧结回转窑完成硫铝酸盐熟料的烧结，窑内温度1100～1300℃，物料在窑内停留时间20～60min，入烧结回转窑风由送煤风和出冷却机的高温空气组成，烧结回转窑出口烟气中含氧气含量控制在2～10％氧化气氛；入还原回转窑风由送煤风和出烧结回转窑的高温烟气组成，烧结回转窑进入还原回转窑的烟气温度为1000～1200℃，还原窑出口烟气中含氧气含量控制在0～1.5％弱氧化气氛，还原回转窑进入还原炉的烟气温度为900～1100℃。When two rotary kilns are used for sintering in series, the deep reduction and clinker sintering are completed in the reduction rotary kiln and the sintering rotary kiln respectively; CaS in the feed and

The oxidation-reduction reaction is completed in the reduction kiln. The temperature in the kiln is 950~1150℃, the material stays in the reduction kiln for 5~30min, and the air entering the kiln is composed of coal supply air and the tail gas of the sintering rotary kiln; The reduced raw material at ℃ enters the sintering rotary kiln through the feeding pipe to complete the sintering of the sulfoaluminate clinker. The temperature in the kiln is 1100-1300 ℃, and the material stays in the kiln for 20-60 minutes. It is composed of high-temperature air leaving the cooler, and the oxygen content in the flue gas at the outlet of the sintering rotary kiln is controlled at 2-10% oxidizing atmosphere; The temperature of the flue gas entering the reduction rotary kiln is 1000-1200°C, the oxygen content in the flue gas at the outlet of the reduction kiln is controlled in a weakly oxidizing atmosphere of 0-1.5%, and the temperature of the flue gas entering the reduction furnace is 900-1100°C.

E. Clinker cooling, heat reuse and purification to produce sulfuric acid

The high-temperature clinker exiting the rotary kiln enters the cooler and exchanges heat with air to cool to (room temperature +65) °C. Part of the high-temperature air exiting the cooler enters the rotary kiln as the combustion-supporting air for fuel, and part enters the combustion chamber of the reduction furnace and is separated by cyclone. The combustion chamber at the outlet of the cyclone is used as the combustion-supporting air for part of the sulfur combustion, and the remaining part is used as the drying heat source for gypsum drying and other raw materials; the sulfur-containing flue gas exiting the first-stage cyclone preheater is recovered by waste heat and dedusted into the subsequent conventional sulfuric acid. The production process carries out washing and purification, drying, conversion, absorption, medium and low temperature waste heat recovery, and final exhaust gas treatment to produce industrial sulfuric acid products.

The cooler is one of a grate cooler, a drum cooler and a vertical cooler.

F. Preparation of cement

The cooling clinker from the cooling machine in step E is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain Belite sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 320-420 m ² /kg, preferably 360 m ² /kg.

According to the content of high-temperature sintered gypsum in the clinker, combined with experiments and calculations, it is determined that no or less gypsum is added, that is, the performance requirements of Belite sulfoaluminate cement products can be met.

C₂S:30～70％，C₃S:0～50％，C₄AF:3～35％，

其他：0～5％。Further, the Belitt sulfoaluminate cement products include ordinary Belitt sulfoaluminate cement, high iron-type Belitt sulfoaluminate cement, high-sulfur Belitt sulfoaluminate cement, high silica type belite sulfoaluminate cement, high belite sulfoaluminate cement, the clinker mineral composition is

C ₂ S: 30～70%, C ₃ S: 0～50%, C ₄ AF: 3～35%,

Others: 0 to 5%.

原料，铝土矿中的氧化铝作为铝质原料，铁作为铁质原料，低价硫作为还原剂促进石膏分解反应，过程中存在

与S₂生成CaS的反应、

与CaS生成CaO的反应、以及CaO与Fe₂O₃、Al₂O₃、SiO₂、

等进行的贝利特硫铝酸盐水泥熟料烧成反应，还原剂形成的气相产物SO₂一并进入烟气中提高了SO₂气浓，有利于后续烟气制酸，产能提高、能耗降低、成本下降，与碳还原相比可减排大量CO₂，为工业副产石膏的资源化直接利用找到了新的出路，该方法是一种工业副产石膏高质高效协同利用的新途径。The present invention adopts the sulfur reduction method to apply gypsum and bauxite to Belite sulfoaluminate cement production, and the gypsum is partially decomposed to obtain CaO as calcium and

Raw materials, alumina in bauxite is used as aluminum raw material, iron is used as iron raw material, and low-price sulfur is used as reducing agent to promote gypsum decomposition reaction.

Reaction with S2 to generate _CaS ,

Reaction with CaS to form CaO, and CaO with Fe ₂ O ₃ , Al ₂ O ₃ , SiO ₂ ,

In the sintering reaction of Belite sulfoaluminate cement clinker, the gas-phase product SO ₂ formed by the reducing agent enters the flue gas together to increase the SO ₂ gas concentration, which is beneficial to the subsequent acid production from the flue gas, the production capacity is increased, and the energy Compared with carbon reduction, a large amount of CO ₂ can be reduced, and a new way has been found for the direct utilization of industrial by-product gypsum. way.

Compared with the prior art, the present invention has the following advantages and characteristics:

分解第一步转化为CaS的气-固预还原反应控制在窑外还原反应炉内还原气氛下进行，将CaS与

固-固氧化还原反应控制在回转窑内弱氧化气氛下进行，使生料中60～90％石膏分解成CaO，可以有效的控制石膏分解量，实现石膏分解出的CaO完全替代贝利特硫铝酸盐水泥生产需要石灰石分解来的CaO，确保贝利特硫铝酸盐水泥熟料主要矿物相达到相关品质指标要求，加入石膏量是贝利特硫铝酸盐水泥中所有钙源与硫源的总和，可最大限度地资源化利用了工业废渣石膏，而且也可以多配入工业石膏通过高温烧结转化为贝利特硫铝酸盐水泥熟料中高温烧结石膏，从而可减少水泥产品后掺石膏的量，生产一吨水泥熟料可以使用工业石膏1.1～1,3吨，既可大量消耗工业石膏，又可节省石灰石和天然石膏资源。1. Compared with other existing Belite sulfoaluminate cements that utilize gypsum, the technology of the present invention effectively converts the gypsum into the gypsum.

The gas-solid pre-reduction reaction of the first step of decomposition into CaS is controlled to be carried out under the reducing atmosphere in the reduction reaction furnace outside the kiln, and the CaS and the

The solid-solid redox reaction is controlled in a weak oxidizing atmosphere in the rotary kiln, so that 60-90% of the gypsum in the raw meal is decomposed into CaO, which can effectively control the amount of gypsum decomposition, and realize that the CaO decomposed from gypsum completely replaces Belite sulfur The production of aluminate cement requires CaO from the decomposition of limestone to ensure that the main mineral phases of Belite sulfoaluminate cement clinker meet the relevant quality index requirements. The sum of the sources can maximize the resource utilization of industrial waste gypsum gypsum, and it can also be mixed with more industrial gypsum and converted into Belite sulfoaluminate cement clinker by high-temperature sintering gypsum, thereby reducing the waste of cement products. The amount of mixed gypsum can use 1.1 to 1.3 tons of industrial gypsum to produce one ton of cement clinker, which can not only consume a large amount of industrial gypsum, but also save limestone and natural gypsum resources.

2. Low-grade bauxite, coal gangue, high-aluminum fly ash or clay can be used as aluminum and siliceous raw materials to meet the requirements of Belite sulfoaluminate cement batching and clinker production, without the need for traditional sulfur aluminum Bauxite must use high-grade bauxite raw materials, which expands the source of raw materials and reduces the cost of raw materials.

3. "Sulfur carbon" replaces coke or anthracite in the existing industrial production technology with sulfur gas as a supplementary reducing agent, so that the pre-reduction reaction of gypsum decomposition changes from solid-solid reaction to gas-solid reaction, and gypsum is decomposed to form CaS The pre-reduction reaction was successfully moved from the kiln to the reduction and decomposition furnace outside the kiln, the pre-reduction reaction temperature was reduced from 900-1200 ℃ in the traditional rotary kiln to 700-980 ℃, and the reaction time was shortened from 15-40 minutes to 2-45 Second, the energy consumption of the pre-reduction reaction is reduced, the reaction time is shortened, and the gypsum decomposition efficiency is improved.

部分转化为CaS的最佳摩尔分率5～22％，即有效地控制了回转窑内

的目标分解率，使石膏分解为CaO的量达到替代石灰石的要求，煅烧分解控制方便，有效保证形成贝利特硫铝酸盐水泥熟料矿物相所要求的CaO和

4. Mix the sulfur gas and the flue gas of the rotary kiln into the bottom of the reduction furnace, and ensure the reduction atmosphere by controlling the amount of sulfur gas added, and control the inside of the reduction reaction furnace while maintaining the reaction temperature.

The optimum molar fraction of partial conversion to CaS is 5-22%, which effectively controls the internal combustion of the rotary kiln.

The target decomposition rate of gypsum can be achieved, so that the amount of gypsum decomposed into CaO can meet the requirements of replacing limestone, and the calcination and decomposition control is convenient, which can effectively ensure the formation of Belite sulfoaluminate cement clinker.

与CaS反应生成SO₂和还原反应炉硫磺还原生成SO₂以及作为燃料的少量硫磺燃烧生产的SO₂的叠加，在还原剂硫磺用量控制最少的条件下获得系统最终尾气中SO₂浓度最高，SO₂组分的摩尔分率可提高到12～18％，对后续硫酸生产SO₂转化、吸收，系统工艺参数优化及生产能力提高极为有利，有利于降低硫酸生产系统设备规格或提高装置生产能力，可实现“二转二吸”和中低温余热回收，工艺设备规格小，综合运行成本低。5. Gas sulfur is used as the reducing gas for solid gypsum material in the reduction reaction furnace. The heat required for gypsum pre-reduction is provided by the combustion of kiln tail flue gas and part of liquid or gas sulfur. It becomes SO ₂ , the precursor for acid production from flue gas. SO ₂ in the flue gas is the rotary kiln

The superposition of the reaction with CaS to generate SO ₂ and the reduction of sulfur in the reduction reactor to generate SO ₂ and the superposition of SO ₂ produced by the combustion of a small amount of sulfur as fuel, the highest concentration of SO ₂ in the final exhaust gas of the system is obtained under the condition that the amount of reducing agent sulfur is controlled at least. The molar fraction of the _two components can be increased to 12-18%, which is extremely beneficial to the subsequent conversion and absorption of SO ₂ in the production of sulfuric acid, the optimization of system process parameters and the improvement of production capacity, and it is beneficial to reduce the equipment specifications of the sulfuric acid production system or improve the production capacity of the device. It can realize "two-rotation and two-suction" and medium and low temperature waste heat recovery, the size of the process equipment is small, and the comprehensive operating cost is low.

6. Since 5-22% of gypsum has been rapidly converted into CaS in the reduction furnace outside the kiln, the decomposition temperature in the kiln is also reduced to 950-1150 °C, and the temperature of the material entering the rotary kiln is increased by more than 150 °C, which greatly shortens the time. The residence time of the material in the rotary kiln.

部分转化为CaS，窑内仅进行

与CaS生成氧化钙的深度氧化还原反应，仅需要控制该反应在弱氧化气氛下进行，相比传统的碳还原窑操作控制容易，反应时间缩短为5～30分钟，回转窑长度缩短～1/4，有利于反应效率和回转窑的容积热负荷提高，使得生产控制易于进行，提高了生产效率。7. Due to the completion of the reduction furnace outside the kiln

Partially converted to CaS, only in the kiln

The deep redox reaction with CaS to generate calcium oxide only needs to control the reaction to be carried out in a weak oxidizing atmosphere. Compared with the traditional carbon reduction kiln, the operation and control are easier, the reaction time is shortened to 5-30 minutes, and the length of the rotary kiln is shortened by ~1/ 4. It is beneficial to improve the reaction efficiency and the volumetric heat load of the rotary kiln, which makes the production control easy to carry out and improves the production efficiency.

8. If phosphogypsum is used as raw material, phosphogypsum contains a small amount of impurities such as P ₂ O ₅ , MgO, Na ₂ O, K ₂ O, F, etc. When Portland cement is fired, P ₂ O ₅ , F, etc. The presence of impurities is detrimental to the quality of cement, and phosphogypsum must be pretreated to ensure that the amount of P ₂ O ₅ in the raw gypsum is controlled within a certain range; while in the sintering of Belite sulfoaluminate cement, a small amount of P ₂ in gypsum Impurities such as O ₅ , MgO, Na ₂ O, K ₂ O, and F act as mineralizers during the sintering process, which are beneficial to the formation of the mineral phase of cement sintering, and are solidified into the mineral phase during the sintering process without affecting the cement Lite the properties of sulfoaluminate cement, so no special pretreatment of phosphogypsum is required.

9. From the use of industrial gypsum instead of limestone as calcium source, sulfur gas to replace coke or sulfur-containing coal as reducing agent, rational organization of technological process to reduce energy consumption, etc., the generation and emission of _CO2 are reduced, which is beneficial to environmental protection.

10. The present invention has the advantages of simple process flow, strong implementability of system control indicators, convenient operation and management, advanced process equipment, low device investment, low energy consumption, low operation cost and high degree of automation.

Description of drawings

Fig. 1 is the overall process flow diagram of the present invention;

2 is a process flow diagram of Embodiment 1 of the present invention;

3 is a process flow diagram of Embodiment 2 of the present invention;

4 is a process flow diagram of Embodiment 3 of the present invention;

5 is a process flow diagram of Embodiment 4 of the present invention;

6 is a process flow diagram of Embodiment 5 of the present invention;

7 is a process flow diagram of Embodiment 6 of the present invention;

8 is a process flow diagram of Embodiment 7 of the present invention;

FIG. 9 is a process flow diagram of Embodiment 8 of the present invention.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, it is the total process flow diagram of the present invention, with industrial by-product gypsum as the main raw material, by controlling alkalinity coefficient (C), aluminum-sulfur ratio ( P) and aluminum-silicon ratio (N), select one or more of low-grade bauxite, fly ash, coal gangue, red mud, clay, and iron slag as ingredients, and use gas sulfur as reducing agent to promote gypsum Decomposition, the Belite sulfoaluminate cement is obtained, and at the same time, a high concentration of gas-phase SO ₂ flue gas is obtained, which is used for subsequent flue gas production of sulfuric acid. Specifically include the following steps:

A. Preparation of gaseous sulfur

The solid or liquid sulfur is heated and melted into crude sulfur liquid, filtered to obtain refined sulfur liquid, gasified to obtain high-temperature gas sulfur, and the Venturi ejector sends the gas sulfur into the reduction furnace;

B. Ingredients

The dehydrated gypsum obtained after the dehydration of the industrial by-product gypsum and the ingredients are mixed and homogenized in a mixer, and further homogenized in a homogenizing silo to obtain a raw meal with uniform composition;

C, preheating and pre-reduction

The raw meal is sent to the multi-stage suspension preheating system for step preheating, the preheated raw meal enters the reduction furnace, and undergoes a reduction reaction with the gas sulfur that enters the reduction furnace in step A, and the reacted material enters the cyclone separator to complete the reduction reaction. Solid separation, the flue gas enters the multi-stage suspension preheating system, and the pre-reduced raw meal enters the rotary kiln;

D. Deep reduction and clinker sintering

Under the weak oxidizing atmosphere, the pre-reduced raw meal undergoes a deep reduction reaction in the rotary kiln, and after the deep reduction, the material is sintered at high temperature to form Belite sulfoaluminate cement clinker;

E. Clinker cooling, heat reuse and purification to produce sulfuric acid

The high-temperature cement clinker exiting the rotary kiln enters the cooler for heat exchange with the cooling air to recover heat, and the sulfur-containing flue gas exiting the first-stage cyclone preheater in the multi-stage suspension preheating system is recovered by waste heat, dedusted and purified, and then enters the follow-up The conventional sulfuric acid production process prepares industrial sulfuric acid products;

F. Preparation of cement

The cement clinker from the cooling machine in step E is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain Belite sulfoaluminate cement products with different performance requirements.

The following is a detailed description through specific embodiments.

Example 1:

The process flow is shown in Figure 2, using phosphogypsum dihydrate, low-grade bauxite, and high-alumina fly ash as raw materials. Most of the coal ash enters the clinker, and the chemical composition of the raw material and raw meal is shown in Table 1.

Table 1 Chemical composition of raw materials and raw meal

project CaO SiO₂ Al₂O₃ Fe₂O₃ MgO P₂O₅ Na₂O SO₃ LOSS total Phosphogypsum 32.56 4.76 0.97 0.39 0.31 1.05 0.30 43.63 15.98 99.95 Bauxite 2.25 24,20 53.51 2.45 0.07 0.00 0.13 0.20 17.98 99.73 fly ash 1.48 43.50 35.38 1.92 0.70 0.00 0.33 0.68 14.77 98.76 Raw material 27.34 10.86 8.18 0.69 0.33 0.87 0.29 36.30 15.96 100.00

的摩尔比为0.3:1，出还原炉物料中硫化钙与未反应的

的摩尔比为在0.21:1。硫磺气体与生料中的

迅速发生气固还原反应，生成固体CaS和SO₂气体，还原炉出口排出的气固混合物经旋风分离器C_5ab进行气固分离，气体继续向上经并联的两路C_4a→C_3a→C_2a→C_1a、C_4b→C_3b→C_2b→C_1b与串联的固体生料在C_1a→C_1b→C_2a→C_2b→C_3a→C_3b→C_4a→C_4b进行传质传热交换，在C_5ab出风口燃烧室补充由冷却机来的920℃空气，使气相中反应残余的硫磺气体燃烧完全生成SO₂，C_1ab出口废气中氧气的体积浓度1.6％、SO₂体积浓度在16％，废气温度320℃，经进一步余热回收、除尘送入后续净化制硫酸系统。The above-mentioned raw materials of phosphogypsum dihydrate, low-grade bauxite and high-alumina fly ash are composed by weight: 82.87 parts of phosphogypsum dihydrate, 7.18 parts of low-grade bauxite, and 9.95 parts of high-alumina fly ash. Mixed evenly, the raw materials are dried and pulverized and then mixed and homogenized, and the raw materials are metered and sent to the gas inlet of the C _1a cyclone preheater to conduct gas _- solid countercurrent flow with the hot gas containing SO2 from the rotary kiln and conveying bed reduction furnace. In contact heat exchange, the solid raw meal undergoes 4-stage heat exchange from top to bottom, and the temperature of the material is raised to 820 °C, and then enters the single-pass conveying bed reduction furnace. The superheated sulfur gas from the sulfur gas gasifier, with a temperature of 680°C, is sent into the combustion chamber at the bottom of the reduction furnace by the Venturi ejector; at the same time, the high temperature flue gas at 930°C from the rotary kiln also enters the combustion chamber of the reduction furnace. , the oxygen content of flue gas is 0.5%. The central temperature of the conveying bed reduction furnace is 890°C, and the minimum residence time of the material in the furnace is 25.5 seconds.

The molar ratio of calcium sulfide and unreacted calcium sulfide in the reduction furnace material is 0.3:1.

The molar ratio is at 0.21:1. Sulfur gas and raw meal

The gas-solid reduction reaction occurs rapidly to generate solid CaS and SO ₂ gas. The gas-solid mixture discharged from the outlet of the reduction furnace is separated from the gas and solid by the cyclone C _5ab , and the gas continues upward through the two parallel paths C _4a → C _3a → C _2a →C _1a , C _4b → C _3b → C _2b → C _1b and the solid raw meal in series at C _1a → C _1b → C _2a → C _2b → C _3a → C _3b → C _4a → C _4b for mass transfer and heat transfer Exchange, supplement the air at 920°C from the cooler in the combustion chamber of the C _5ab outlet, so that the residual sulfur gas in the gas phase is completely burned to generate SO ₂ , the volume concentration of oxygen in the exhaust gas at the C _1ab outlet is 1.6%, and the volume concentration of SO ₂ is 16%, the exhaust gas temperature is 320 ℃, after further waste heat recovery and dust removal, it is sent to the subsequent purification system for sulfuric acid production.

的分解反应，窑内温度1030～1170℃，深度还原后物料进入烧结回转窑经高温烧结形成贝利特硫铝酸盐水泥熟料矿物，窑内烧结段温度1150～1250℃，熟料由窑头排出进入熟料冷却机。The solid material separated by C _5ab is sent to the reduction rotary kiln through the discharge pipe, and CaS and

The temperature in the kiln is 1030~1170℃. After the deep reduction, the material enters the sintering rotary kiln and is sintered at high temperature to form Belite sulfoaluminate cement clinker minerals. The temperature of the sintering section in the kiln is 1150~1250℃. The head is discharged into the clinker cooler.

The chemical composition of the clinker and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 2 and Table 3, respectively.

Table 2 Chemical composition of clinker

Table 3 Clinker Mineral Phase Composition

The cooling clinker from the cooler is added with gypsum and composite materials, and then processed by subsequent grinding to obtain Belite sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 400m ² /kg.

Example 2

The process flow is shown in Figure 3. Dihydrate phosphogypsum and high alumina fly ash are used as raw materials. The raw materials are dried and pulverized to >95%-80μm. The chemical compositions of raw materials and raw materials are shown in Table 4.

Table 4 Chemical composition of raw materials and raw meal

project CaO SiO₂ Al₂O₃ Fe₂O₃ MgO P₂O₅ Na₂O SO₃ LOSS total Phosphogypsum 32.56 4.76 0.97 0.39 0.31 1.05 0.30 43.63 15.98 99.95 fly ash 1.48 43.50 35.38 1.92 0.70 0.00 0.33 0.68 14.77 99.73 Raw material 27.72 10.91 6.42 0.63 0.37 0.89 0.31 36.93 15.83 100.00

的摩尔比为0.31:1，出还原炉物料中硫化钙与未反应的

的摩尔比为在0.22:1。硫磺气体与生料中的

迅速发生气固还原反应，生成固体CaS和SO₂气体，还原炉出口排出的气固混合物经旋风分离器C_6ab进行气固分离，气体继续向上经并联的两路C_5a→C_4a→C_3a→C_2a→C_1a、C_5b→C_4b→C_3b→C_2b→C_1b与串联的固体生料在C_1a→C_1b→C_2a→C_2b→C_3a→C_3b→C_4a→C_4b→C_5a→C_5b进行传质传热交换，在C_6ab出风口燃烧室补充由冷却机来的900℃空气，使气相中反应残余的硫磺气体燃烧完全生成SO₂，C_1ab出口废气中氧气的体积浓度1.0％、SO₂体积浓度在17％，废气温度280℃，经进一步余热回收、除尘送入后续制硫酸系统。The above-mentioned phosphogypsum dihydrate and high-alumina fly ash raw materials are composed in parts by weight: 84.2 parts of phosphogypsum dihydrate and 15.8 parts of high-alumina fly ash are mixed uniformly, and the raw materials are mixed and homogenized after drying and grinding, After the raw meal is metered, it is sent to the gas inlet of the C _1a cyclone preheater to conduct gas _- solid countercurrent contact heat exchange with the hot gas containing SO2 from the rotary kiln and conveying bed reduction furnace. The solid raw meal passes through 5 stages from top to bottom. After heat exchange, the temperature of the material is raised to 870 ° C, and it enters the external circulating conveying bed reduction furnace with an external separator. The superheated sulfur gas from the sulfur gas gasifier, with a temperature of 700°C, is sent into the combustion chamber at the bottom of the reduction furnace by the Venturi ejector; at the same time, the 960°C high-temperature flue gas from the rotary kiln also enters the combustion chamber of the reduction furnace. , the oxygen content of flue gas is 0.5%. The central temperature of the conveying bed reduction furnace is 880°C, and the minimum residence time of the material in the furnace is 20 seconds.

The molar ratio is 0.31:1, calcium sulfide and unreacted calcium sulfide in the reduction furnace material

The molar ratio is at 0.22:1. Sulfur gas and raw meal

The gas-solid reduction reaction occurs rapidly to generate solid CaS and SO ₂ gas. The gas-solid mixture discharged from the outlet of the reduction furnace is separated from the gas and solid by the cyclone C _6ab , and the gas continues upward through the parallel two-way C _5a →C _4a →C _3a →C _2a → C _1a , C _5b → C _4b → C _3b → C _2b → C _1b with solid raw meal in series at C _1a → C _1b → C _2a → C _2b → C _3a → C _3b → C _4a → C _4b → C _5a → C _5b for mass transfer and heat transfer, supplement the 900 ℃ air from the cooler in the combustion chamber of the C _6ab outlet, so that the residual sulfur gas in the gas phase is completely burned to form SO ₂ , and the exhaust gas at the C _1ab outlet is The volume concentration of oxygen is 1.0%, the volume concentration of SO ₂ is 17%, and the exhaust gas temperature is 280°C. After further waste heat recovery and dust removal, it is sent to the subsequent sulfuric acid production system.

的分解反应，窑内深度还原段温度1050～1180℃，随着物料温度升高停留时间延长，还原物料进入烧结段经高温烧结形成高贝利特硫铝酸盐水泥熟料矿物，窑内温度1170～1280℃，熟料由窑头排出进入熟料冷却机。The solid material separated by C _6ab is sent to the rotary kiln through the discharge pipe, and the CaS and the

The temperature of the deep reduction section in the kiln is 1050-1180 °C. As the temperature of the material increases, the residence time is prolonged, and the reduced material enters the sintering section and is sintered at high temperature to form high Belite sulfoaluminate cement clinker minerals. The temperature in the kiln increases. At 1170～1280℃, the clinker is discharged from the kiln head and enters the clinker cooler.

The chemical composition of the clinker and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 5 and Table 6, respectively.

Table 5 Chemical composition of clinker

Table 6 Clinker Mineral Phase Composition

The cooling clinker from the cooler is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain high Belitt sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 360m ² /kg .

Example 3

The process flow is shown in Figure 4. Dihydrate phosphogypsum and coal gangue are used as raw materials. The raw materials are dried and pulverized to >95%-80μm. Most of the fly ash produced by the combustion of the fuel coal in the rotary kiln enters the clinker. Its chemical composition is shown in Table 7.

Table 5 Chemical composition of raw materials and raw meal

project CaO SiO₂ Al₂O₃ Fe₂O₃ MgO P₂O₅ Na₂O SO₃ LOSS total Phosphogypsum 32.56 4.76 0.97 0.39 0.31 1.05 0.30 43.63 15.98 99.95 gangue 1.34 42.74 36.23 4.69 1.26 0.00 0.24 1.35 11.27 99.12 Raw material 27.61 10.86 6.63 1.08 0.46 0.88 0.29 36.92 15.25 100.00

的摩尔比为0.33:1，出还原炉物料中硫化钙与未反应的

的摩尔比为在0.19:1。硫磺气体与生料中的

迅速发生气固还原反应，生成固体CaS和SO₂气体，还原炉出口排出的气固混合物经旋风分离器C₆进行气固分离，气体继续向上经C₅→C₄→C₃→C₂→C₁与固体生料在C₁→C₂→C₃→C₄→C₅进行传质传热交换，在C₆出风口燃烧室补充由冷却机来的940℃空气，使气相中反应残余的硫磺气体燃烧完全生成SO₂，C₁出口废气中氧气的体积浓度1.5％、SO₂体积浓度在14.5％，废气温度350℃，经进一步余热回收、除尘送入后续净化制硫酸系统。The above-mentioned phosphogypsum dihydrate and coal gangue raw materials by weight percentage are: 84.0 parts of phosphogypsum dihydrate and 16.0 parts of coal gangue are mixed evenly. The gas inlet of the C ₁ cyclone preheater conducts gas-solid countercurrent contact heat exchange with the hot gas containing SO ₂ from the rotary kiln and the conveying bed reduction furnace. To 830 ℃, enter the single-pass conveying bed reduction furnace. The superheated sulfur gas from the sulfur gas gasifier, with a temperature of 750℃, is sent into the combustion chamber at the bottom of the reduction furnace by the Venturi ejector; at the same time, the high temperature flue gas from the rotary kiln of 940℃ also enters the combustion chamber of the reduction furnace. , the oxygen content of flue gas is 1.0%. The central temperature of the conveying bed reduction furnace is 900°C, and the minimum residence time of the material in the furnace is 33 seconds.

The molar ratio of calcium sulfide and unreacted calcium sulfide in the reduction furnace material is 0.33:1.

The molar ratio is at 0.19:1. Sulfur gas and raw meal

The gas-solid reduction reaction occurs rapidly to generate solid CaS and SO ₂ gas. The gas-solid mixture discharged from the outlet of the reduction furnace is separated from the gas and solid by the cyclone C ₆ , and the gas continues to pass upward through C ₅ →C ₄ →C ₃ →C ₂ → C ₁ and solid raw meal conduct mass transfer and heat transfer exchange at C ₁ →C ₂ →C ₃ →C ₄ →C ₅ , and supplement the 940 ℃ air from the cooler at the C ₆ air outlet combustion chamber to make the reaction residual in the gas phase The sulfur gas is burnt to completely generate SO ₂ , the volume concentration of oxygen in the C ₁ outlet exhaust gas is 1.5%, the volume concentration of SO ₂ is 14.5%, and the exhaust gas temperature is 350 ℃. After further waste heat recovery and dust removal, it is sent to the subsequent purification sulfuric acid system.

的分解反应，窑内还原温度1000～1160℃，还原物料进入烧结还原窑经高温烧结形成高贝利特硫铝酸盐水泥熟料矿物，窑内烧结段温度1140～1260℃，熟料由窑头排出进入熟料冷却机。The solid material separated by C ₆ is sent to the reduction rotary kiln through the discharge pipe, and CaS and

The reduction temperature in the kiln is 1000～1160℃, the reducing material enters the sintering reduction kiln and is sintered at high temperature to form high-belite sulfoaluminate cement clinker minerals. The head is discharged into the clinker cooler.

The chemical composition of the clinker and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 8 and Table 9, respectively.

Table 8 Chemical composition of clinker

Table 9 Clinker Mineral Phase Composition

The cooling clinker from the cooler is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain high Belitt sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 390m ² /kg .

Example 4

The process flow is shown in Figure 5. Desulfurized gypsum and coal gangue are used as raw materials. The raw materials are dried and pulverized to >95%-80μm. See Table 10.

Table 10 Chemical composition of raw materials and raw meal

project CaO SiO₂ Al₂O₃ Fe₂O₃ MgO Na₂O SO₃ LOSS total Desulfurized gypsum 34.40 1.56 1.78 1.15 2.24 0.15 41.56 17.06 99.85 gangue 1.34 42.74 36.23 4.69 1.26 0.24 1.35 11.27 99.12 Raw material 27.80 9.87 8.73 1.87 2.05 0.17 33.58 15.94 100.00

的摩尔比为0.29:1，出还原炉物料中硫化钙与未反应的

的摩尔比为在0.19:1。硫磺气体与生料中的

迅速发生气固还原反应，生成固体CaS和SO₂气体，还原炉出口排出的气固混合物经旋风分离器C₆进行气固分离，气体继续向上经C₅→C₄→C₃→C₂→C₁与固体生料在C₁→C₂→C₃→C₄→C₅进行传质传热交换，在C₆出风口燃烧室补充由冷却机来的940℃空气，使气相中反应残余的硫磺气体燃烧完全生成SO₂，C₁出口废气中氧气的体积浓度2.0％、SO₂体积浓度在15.7％，废气温度310℃，经进一步余热回收、除尘送入后续净化制硫酸系统。The above-mentioned titanium gypsum dihydrate and bauxite raw materials are composed in parts by weight as follows: 79.9 parts of titanium gypsum dihydrate and 20.1 parts of coal gangue are mixed uniformly, and the raw materials are mixed and homogenized after drying and grinding. The gas inlet of the C ₁ cyclone preheater conducts gas-solid countercurrent contact heat exchange with the hot gas containing SO ₂ from the rotary kiln and conveying bed reduction furnace, and the solid raw meal passes through 5-stage heat exchange from top to bottom. The temperature is raised to 850 ℃, and it enters the external circulating conveying bed reduction furnace with an external separator. The superheated sulfur gas from the sulfur gas gasifier, with a temperature of 670°C, is sent into the combustion chamber at the bottom of the reduction furnace by the Venturi ejector; at the same time, the high temperature flue gas from the rotary kiln at 960°C also enters the combustion chamber of the reduction furnace. , the oxygen content of flue gas is 1.1%. The central temperature of the conveying bed reduction furnace is 910°C, and the minimum residence time of the material in the furnace is 26 seconds.

The molar ratio is 0.29:1, the calcium sulfide and unreacted calcium sulfide in the reduction furnace material

The molar ratio is at 0.19:1. Sulfur gas and raw meal

The gas-solid reduction reaction occurs rapidly to generate solid CaS and SO ₂ gas. The gas-solid mixture discharged from the outlet of the reduction furnace is separated from the gas and solid by the cyclone C ₆ , and the gas continues to pass upward through C ₅ →C ₄ →C ₃ →C ₂ → C ₁ and solid raw meal conduct mass transfer and heat transfer exchange at C ₁ →C ₂ →C ₃ →C ₄ →C ₅ , and supplement the 940 ℃ air from the cooler at the C ₆ air outlet combustion chamber to make the reaction residual in the gas phase The sulfur gas is burnt to completely generate SO ₂ , the volume concentration of oxygen in the C ₁ outlet exhaust gas is 2.0%, the volume concentration of SO ₂ is 15.7%, and the temperature of the exhaust gas is 310 ℃. After further waste heat recovery and dust removal, it is sent to the subsequent purification sulfuric acid system.

的分解反应，窑内深度还原段温度1020～1150℃，随着温度升高停留时间延长，还原物料进入烧结段经高温烧结形成贝利特硫铝酸盐水泥熟料矿物，窑内烧结段温度1150～1270℃，熟料由窑头排出进入熟料冷却机。The solid material separated by _C6 is sent to the rotary kiln through the discharge pipe, where CaS and CaS are generated.

The temperature of the deep reduction section in the kiln is 1020-1150 °C. As the temperature rises, the residence time is prolonged, and the reducing material enters the sintering section and is sintered at high temperature to form Belite sulfoaluminate cement clinker minerals. The temperature in the sintering section of the kiln is 1150～1270℃, the clinker is discharged from the kiln head into the clinker cooler.

The chemical composition of the clinker and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 11 and Table 12, respectively.

Table 11 Chemical composition of clinker

Table 12 Clinker Mineral Phase Composition

The cooled clinker from the cooler is added with gypsum and composite materials, and then processed by subsequent grinding to obtain Belite sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 350m ² /kg.

Example 5

The process flow is shown in Figure 6. Titanium gypsum and coal gangue are used as raw materials. The raw materials are dried and pulverized to >95%-80μm. The ingredients are shown in Table 13.

Table 13 Chemical composition of raw materials and raw meal

project CaO SiO₂ Al₂O₃ Fe₂O₃ MgO TiO₂ Na₂O SO₃ LOSS total Titanium gypsum 29.50 2.50 2.03 2.64 0.83 1.60 0.15 37.54 22.90 99.69 gangue 1.34 42.74 36.23 4.69 1.26 0.85 0.24 1.35 11.27 99.97 Raw material 25.60 8.19 6.86 2.94 0.89 1.50 0.16 32.53 21.32 100.00

的摩尔比为0.26:1，出还原炉物料中硫化钙与未反应的

的摩尔比为在0.22:1。硫磺气体与生料中的

迅速发生气固还原反应，生成固体CaS和SO₂气体，还原炉出口排出的气固混合物经旋风分离器C₇进行气固分离，气体继续向上经C₆→C₅→C₄→C₃→C₂→C₁与固体生料在C₁→C₂→C₃→C₄→C₅→C₆进行传质传热交换，在C₇出风口燃烧室补充由冷却机来的935℃空气，使气相中反应残余的硫磺气体燃烧完全生成SO₂，C₁出口废气中氧气的体积浓度0.8％、SO₂体积浓度在14.4％，废气温度270℃，经进一步余热回收、除尘送入后续净化制硫酸系统。The above-mentioned titanium gypsum and coal gangue raw materials are composed in parts by weight as follows: 85.9 parts of titanium gypsum and _14.1 parts of coal gangue are mixed uniformly, the raw materials are dried and pulverized, and the mixture is homogenized. The gas inlet of the preheater conducts gas-solid countercurrent contact heat exchange with the hot gas containing SO ₂ from the rotary kiln and the conveying bed reduction furnace. , into the single-pass conveyor bed reduction furnace. The superheated sulfur gas from the sulfur gas gasifier, with a temperature of 650°C, is sent into the combustion chamber at the bottom of the reduction furnace by the Venturi ejector; at the same time, the high temperature flue gas from the rotary kiln at 990°C also enters the combustion chamber of the reduction furnace. , the oxygen content of flue gas is 0.3%. The central temperature of the conveying bed reduction furnace is 830℃, and the maximum residence time of the material in the skull is 18 seconds.

The molar ratio is 0.26:1, calcium sulfide and unreacted calcium sulfide in the reduction furnace material

The molar ratio is at 0.22:1. Sulfur gas and raw meal

The gas-solid reduction reaction occurs rapidly to generate solid CaS and SO ₂ gases. The gas-solid mixture discharged from the outlet of the reduction furnace is separated from the gas and solid by the cyclone C ₇ , and the gas continues to pass upward through C ₆ →C ₅ →C ₄ →C ₃ → C ₂ →C ₁ and solid raw meal at C ₁ → C ₂ → C ₃ → C ₄ → C ₅ → C ₆ for mass transfer and heat transfer, and at C ₇ the air outlet combustion chamber is supplemented with 935°C air from the cooler , so that the residual sulfur gas in the gas phase is burnt to completely generate SO ₂ , the volume concentration of oxygen in the exhaust gas at the C ₁ outlet is 0.8%, the volume concentration of SO ₂ is 14.4%, and the temperature of the exhaust gas is 270 ° C. After further waste heat recovery and dust removal, it is sent to subsequent purification. Sulfuric acid system.

的分解反应，窑内温度1000～1150℃；出窑物料进入烧结回转窑高温烧结形成高铁型贝利特硫铝酸盐水泥熟料矿物，窑内温度1100～1260℃，熟料由窑头排出进入熟料冷却机。The solid material separated by C ₇ is sent to the reduction rotary kiln through the discharge pipe, and CaS and

The temperature in the kiln is 1000～1150℃; the material out of the kiln enters the sintering rotary kiln to be sintered at high temperature to form high-speed Belite sulfoaluminate cement clinker minerals. The temperature in the kiln is 1100～1260℃, and the clinker is discharged from the kiln head. Enter the clinker cooler.

The chemical composition of the clinker and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 14 and Table 15, respectively.

Table 14 Chemical composition of clinker

Table 15 Clinker Mineral Phase Composition

The cooling clinker from the cooler is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain high-speed iron-type Belite sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 380m ² / kg.

Example 6

The process flow is shown in Figure 7. Dihydrate phosphogypsum and red mud are used as raw materials. The raw materials are dried and pulverized to >95%-80μm. Most of the fly ash produced by the combustion of fuel coal in the rotary kiln enters the clinker. Its chemical composition is shown in Table 16.

Table 16 Chemical composition of raw materials and raw meal

project CaO SiO₂ Al₂O₃ Fe₂O₃ P₂O₅ TiO₂ Na₂O SO₃ LOSS total Phosphogypsum 32.56 4.76 0.97 0.39 1.05 0.00 0.30 43.63 15.98 99.64 red mud 11.47 20.35 23.37 15.84 0.00 5.16 4.11 1.26 15.52 97.08 Raw material 27.70 8.64 6.48 4.19 0.80 1.27 1.24 33.66 16.03 100.00

的摩尔比为0.26:1，出还原炉物料中硫化钙与未反应的

的摩尔比为在0.22:1。硫磺气体与生料中的

迅速发生气固还原反应，生成固体CaS和SO₂气体，还原炉出口排出的气固混合物经旋风分离器C₅进行气固分离，气体继续向上经C₄→C₃→C₂→C₁与固体生料在C₁→C₂→C₃→C₄进行传质传热交换，在C₅出风口燃烧室补充由冷却机来的935℃空气，使气相中反应残余的硫磺气体燃烧完全生成SO₂，C₁出口废气中氧气的体积浓度0.8％、SO₂体积浓度在16.4％，废气温度260℃，经进一步余热回收、除尘送入后续净化制硫酸系统。The above-mentioned phosphogypsum dihydrate and red mud raw materials are composed in parts by weight as follows: 75.7 parts of phosphogypsum dihydrate and 24.3 parts of red mud are mixed uniformly, the raw materials are mixed and homogenized after drying and grinding, and the raw materials are measured and sent to Enter the gas inlet of the C ₁ cyclone preheater, and conduct gas-solid countercurrent contact heat exchange with the hot gas containing SO ₂ from the rotary kiln and the conveying bed reduction furnace. Raised to 875 ℃, entering the external circulation type conveying bed reduction furnace with external separator. The superheated sulfur gas from the sulfur gas gasifier, with a temperature of 650°C, is sent into the combustion chamber at the bottom of the reduction furnace by the Venturi ejector; at the same time, the high temperature flue gas from the rotary kiln at 990°C also enters the combustion chamber of the reduction furnace. , the oxygen content of flue gas is 0.3%. The central temperature of the conveying bed reduction furnace is 830℃, and the maximum residence time of the material in the skull is 18 seconds.

The molar ratio is 0.26:1, calcium sulfide and unreacted calcium sulfide in the reduction furnace material

The molar ratio is at 0.22:1. Sulfur gas and raw meal

The gas-solid reduction reaction occurs rapidly to generate solid CaS and SO ₂ gas. The gas-solid mixture discharged from the outlet of the reduction furnace is separated from the gas and solid by the cyclone C ₅ , and the gas continues upward through C ₄ →C ₃ →C ₂ →C ₁ and The solid raw meal undergoes mass transfer and heat transfer at C ₁ →C ₂ →C ₃ →C ₄ , and the 935°C air from the cooler is supplemented in the combustion chamber of the C ₅ air outlet, so that the residual sulfur gas in the gas phase is completely burned and generated. SO ₂ , the volume concentration of oxygen in the exhaust gas at the C ₁ outlet is 0.8%, the volume concentration of SO ₂ is 16.4%, and the exhaust gas temperature is 260 ° C. After further waste heat recovery and dust removal, it is sent to the subsequent purification system for sulfuric acid production.

的分解反应，窑内深度还原段温度1000～1150℃，随着温度升高停留时间延长，还原物料进入烧结段经高温烧结形成高铁型贝利特硫铝酸盐水泥熟料矿物，窑内温度1100～1260℃，熟料由窑头排出进入熟料冷却机。The solid material separated by _C5 is sent to the rotary kiln through the discharge pipe, and CaS and

The temperature of the deep reduction section in the kiln is 1000-1150 °C. As the temperature rises, the residence time is prolonged, and the reduced material enters the sintering section and is sintered at high temperature to form high-iron Belite sulfoaluminate cement clinker minerals. The temperature in the kiln increases. 1100～1260℃, the clinker is discharged from the kiln head into the clinker cooler.

The chemical composition of the clinker and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 17 and Table 18, respectively.

Table 17 Chemical composition of clinker

Table 18 Clinker Mineral Phase Composition

The cooling clinker from the cooler is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain high-speed iron Belite sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 350m ² / kg.

Example 7

Referring to Fig. 8, the process flow shows a method for co-producing sulfuric acid by reducing gypsum-containing raw meal to produce Belite sulfoaluminate cement by sulfur gas, comprising the following steps:

A. Preparation of gaseous sulfur

The solid sulfur is introduced into the sulfur melting tank and heated to 120 ℃ by steam to melt into a crude sulfur liquid, which is filtered through a sulfur filter to obtain a refined sulfur liquid, which is then sent to a gasifier after being measured by a transfer pump and heated to 470 ℃. The high-temperature gas sulfur is obtained, and the Venturi ejector sends the gas sulfur into the reduction furnace.

B. Drying, grinding and ingredients

The industrial by-product gypsum is dried and dehydrated at 120 ℃ in the conveying bed drying furnace. The bauxite, siliceous correction material and iron correction material are dried, ground and initially mixed in the mill. The drying heat source is a cooler ( The high-temperature surplus air discharged from the optional grate cooler) and the heat source recovered from the low-temperature waste heat in the co-production of sulfuric acid; dehydrated gypsum, bauxite, siliceous correction material and iron correction material are mixed and homogenized in a mixer, and Further homogenization is carried out in the homogenization silo to obtain a raw meal with uniform composition. Dehydrated gypsum and bauxite, siliceous correction material and iron correction material are based on the three rate values usually required by Belitt sulfoaluminate cement clinker process: alkalinity coefficient (C), aluminum-sulfur ratio (P), aluminum The silicon ratio (N) is used to calculate the batching ratio, and these ratios are used to adjust the raw material ratio of Belite sulphoaluminate and control the components of cement clinker to produce different varieties of Belite sulphoaluminate cement clinker.

In this embodiment, phosphogypsum, coal gangue, bauxite, red mud, clay, iron slag, and fly ash are used as raw materials. Most of the fly ash entered into the clinker, and its chemical composition is shown in Table 19.

Table 19 Chemical composition of raw materials and raw meal

project CaO SiO₂ Al₂O₃ Fe₂O₃ MgO P₂O₅ Na₂O SO₃ LOSS total Phosphogypsum 32.56 4.76 0.97 0.39 0.31 1.05 0.30 43.63 15.98 99.95 gangue 21.82 30.15 16.56 3.45 0.71 0.09 0.00 11.95 15.27 100.00 Bauxite 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 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 28.24 10.69 6.57 1.77 0.36 0.83 0.31 35.49 15.73 100.00

In this embodiment, the ratio of the raw meal is the alkalinity coefficient C: 0.97, the ratio of aluminum to sulfur is P: 1.55, and the ratio of aluminum to silicon is N: 0.53; the main raw material ingredients that meet the above ratio values are 78.3 parts of gypsum, 78.3 parts of bauxite 2.1 parts of ore, 7.2 parts of fly ash, 9.5 parts of coal gangue, 1.0 part of red mud, 0.8 part of clay, and 1.0 part of iron slag. The gypsum is dihydrate gypsum; the mass fraction of the bauxite Al ₂ O ₃ is 44.18%.

The industrial by-product gypsum is phosphogypsum dihydrate.

C. Preheating and pre-reduction

中硫的摩尔比为0.5:1，炉内温度700℃，出还原炉的生料中硫化钙(CaS)与未分解的

的摩尔比为0.18:1；生料随烟气离开还原炉后，进入旋风分离器完成气固分离，烟气进入多级悬浮预热系统，温度为700℃的预还原生料进入回转窑。最顶层旋风预热器出口温度为200℃。The raw meal from step B is metered and sent to the top cyclone preheater of the 4-stage double-row suspension preheating system, and the gas-solid heat exchange and separation are quickly completed with the hot air flow from the reduction furnace in the cyclone preheater. Then pass through the lower cyclone preheaters at all levels to complete the step preheating within 20 seconds; the preheated raw meal enters the external circulating conveying bed reduction furnace with the external separator, and the high temperature flue gas from the reduction kiln Carrying down reacts with gaseous sulfur within 10 seconds, sulfur and raw meal

The molar ratio of sulfur in the furnace is 0.5:1, and the temperature in the furnace is 700 °C.

After the raw meal leaves the reduction furnace with the flue gas, it enters the cyclone separator to complete the gas-solid separation, the flue gas enters the multi-stage suspension preheating system, and the pre-reduced raw meal with a temperature of 700 ℃ enters the rotary kiln. The outlet temperature of the top cyclone preheater is 200°C.

D. Deep reduction and clinker sintering

在窑内950℃下发生氧化还原反应，物料在还原窑内还原时间为15min，～88％S元素以SO₂的形式进入窑内烟气中，其它元素发生初步的固相反应；深度还原之后的物料进入烧结回转窑在1100～1250℃烧结并形成高贝利特硫铝酸盐水泥熟料，物料在回转窑内的烧结时间为55min。The pre-reduced raw meal enters the reduction kiln through the feeding pipe, and the oxygen content in the flue gas at the outlet of the rotary kiln is controlled to be less than 2%.

Oxidation-reduction reaction occurs in the kiln at 950 °C, the reduction time of the material in the reduction kiln is 15min, ~88% S element enters the flue gas in the kiln in the form of SO ₂ , and other elements undergo a preliminary solid-phase reaction; after deep reduction The sintered material enters the sintering rotary kiln and is sintered at 1100-1250 ℃ to form high belite sulfoaluminate cement clinker. The sintering time of the material in the rotary kiln is 55min.

The sintered fuel is sulfur-containing coal.

E. Clinker cooling, heat reuse and purification to produce sulfuric acid

The high-temperature clinker exiting the rotary kiln enters the grate cooler and exchanges heat with the air to cool to (room temperature + 65) ℃, part of the high-temperature air exiting the grate cooler enters the rotary kiln as the combustion-supporting air for fuel, and part enters the reduction furnace combustion chamber and The combustion chamber at the outlet of the cyclone separator is used as combustion-supporting air for part of the sulfur combustion, and the remaining part is used as the drying heat source for gypsum drying and other raw materials; the sulfur-containing flue gas exiting the first-stage cyclone preheater is recovered by waste heat and dedusted, and then enters the subsequent routine In the sulfuric acid production process, washing and purification, drying, conversion, absorption, medium and low temperature waste heat recovery, and final tail gas treatment are carried out to produce industrial sulfuric acid products.

The chemical composition of the clinker in this example and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 20 and Table 21, respectively.

Table 20 Chemical composition of clinker

Table 21 Clinker Mineral Phase Composition

F. Preparation of cement

The cooled clinker from the grate cooler in step E is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain high Belite sulfoaluminate cement products with different performance requirements. The product fineness is ground to a specific surface area of 350m. ² /kg.

Example 8

Referring to Figure 9, the process flow shows a method for co-producing sulfuric acid by reducing gypsum-containing raw meal to produce Belite sulfoaluminate cement by sulfur gas, comprising the following steps:

A. Preparation of gaseous sulfur

The solid or liquid sulfur is introduced into the sulfur melting tank and heated to 160 ℃ indirectly by steam or heat transfer oil or electricity to melt into a crude sulfur liquid, which is filtered by a sulfur filter to obtain a refined sulfur liquid, which is then sent to the gasifier after being metered by a transfer pump. It is heated and gasified to 900 ℃ to obtain high-temperature gas sulfur, and the Venturi ejector sends the gas sulfur into the reduction furnace.

B. Drying, grinding and ingredients

The industrial by-product gypsum is dried and dehydrated at 300 ℃ in the conveying bed drying furnace. The bauxite, siliceous correction material and iron correction material are dried, ground, and initially mixed in the mill. The drying heat source is a cooler ( The high-temperature excess air discharged from the optional drum cooler) and the heat source recovered from the low-temperature waste heat in the co-production of sulfuric acid; dehydrated gypsum, bauxite, siliceous correction material and iron correction material are mixed and homogenized in a mixer, and Further homogenization is carried out in the homogenization silo to obtain a raw meal with uniform composition. Dehydrated gypsum and bauxite, siliceous correction material and iron correction material are based on the three rate values usually required by Belitt sulfoaluminate cement clinker process: alkalinity coefficient (C), aluminum-sulfur ratio (P), aluminum The silicon ratio (N) is used to calculate the batching ratio, and these ratios are used to adjust the raw material ratio of Belite sulphoaluminate and control the components of cement clinker to produce different varieties of Belite sulphoaluminate cement clinker.

In this embodiment, phosphogypsum, coal gangue, low-grade bauxite, red mud, clay, iron slag, and fly ash are used as raw materials. Most of the fly ash produced by combustion enters into the clinker, and its chemical composition is shown in Table 22.

Table 22 Chemical composition of raw materials and raw meal

The ratio of the raw meal is the alkalinity coefficient C: 0.97, the ratio of aluminum to sulfur is P: 1.82, and the ratio of aluminum to silicon is N: 0.87; the main raw material ingredients that meet the above ratio values are 71.1 parts of phosphogypsum, 8.2 parts of coal gangue, and 8.2 parts of aluminum. 13.0 parts of soil, 1.0 parts of red mud, 1.5 parts of iron slag, 1.0 parts of clay, and 4.1 parts of fly ash; the mass fraction of Al ₂ O ₃ of the bauxite is 44.18%, and the industrial by-product gypsum is phosphorus hemihydrate plaster.

C. Preheating and pre-reduction

中硫的摩尔比为0.7:1，炉内温度980℃，出还原炉的生料中硫化钙(CaS)与未分解的

的摩尔比为0.35:1；生料随烟气离开还原炉后，进入旋风分离器完成气固分离，烟气进入多级悬浮预热系统，温度为950℃的预还原生料进入回转窑。最顶层旋风预热器出口温度为400℃，通过检测最顶层旋风预热器出口烟气中的氧含量0.3～1.5％(v/v)。The raw meal from step B is metered and sent to the top cyclone preheater of the 6-stage double-row suspension preheating system, and the gas-solid heat exchange and separation are quickly completed with the hot air flow from the reduction furnace in the cyclone preheater. Then pass through the lower cyclone preheaters at all levels to complete the step preheating within 60 seconds; the preheated raw meal enters the external circulating conveying bed reduction furnace with the external separator, and the high temperature flue gas from the rotary kiln is discharged. Carrying down reacts with gaseous sulfur within 45 seconds, sulfur and raw meal

The molar ratio of sulfur in the furnace is 0.7:1, and the temperature in the furnace is 980 °C.

After the raw meal leaves the reduction furnace with the flue gas, it enters the cyclone separator to complete the gas-solid separation, the flue gas enters the multi-stage suspension preheating system, and the pre-reduced raw meal with a temperature of 950 ℃ enters the rotary kiln. The outlet temperature of the top cyclone preheater is 400°C, and the oxygen content in the flue gas at the outlet of the top cyclone preheater is 0.3-1.5% (v/v).

D. Deep reduction and clinker sintering

在窑内1150℃下发生氧化还原反应，物料在窑内还原时间为10～30min，～65％S元素以SO₂的形式进入窑内烟气中，其它元素发生初步的固相反应；深度还原之后的物料在1300℃烧结并形成高硅型贝利特硫铝酸盐水泥熟料，物料的烧结时间为20min。The pre-reduced raw meal enters the rotary kiln through the feeding pipe, and the oxygen content in the flue gas at the outlet of the rotary kiln is controlled to be less than 2%.

Oxidation-reduction reaction occurs in the kiln at 1150 ℃, the reduction time of the material in the kiln is 10-30min, ~65% S element enters the flue gas in the kiln in the form of SO ₂ , and other elements undergo a preliminary solid-phase reaction; deep reduction The material after that is sintered at 1300° C. to form high-silica Belite sulfoaluminate cement clinker, and the sintering time of the material is 20 minutes.

E. Clinker cooling, heat reuse and purification to produce sulfuric acid

The high-temperature clinker exiting the rotary kiln enters the cooler and exchanges heat with the air to cool to (room temperature +65) °C. Part of the high-temperature air exiting the cooler enters the rotary kiln as the combustion-supporting air for fuel, and part enters the combustion chamber of the reduction furnace and is separated by a cyclone. The combustion chamber at the outlet of the cyclone is used as the combustion-supporting air for part of the sulfur combustion, and the remaining part is used as the drying heat source for gypsum drying and other raw materials; the sulfur-containing flue gas from the first-stage cyclone preheater is recovered by waste heat and dedusted, and then enters the subsequent conventional sulfuric acid. The production process carries out washing and purification, drying, conversion, absorption, medium and low temperature waste heat recovery, and final exhaust gas treatment to prepare industrial sulfuric acid products.

The chemical composition of the clinker in this example and the mineral composition of the clinker determined by the quantitative analysis method of XRD diffraction are shown in Table 20 and Table 21, respectively.

Table 20 Chemical composition of clinker

Table 21 Clinker Mineral Phase Composition

F. Preparation of cement

The cooling clinker from the cooling machine in step E is added with gypsum and composite materials, and then subjected to subsequent grinding to obtain high-silicon Belite sulfoaluminate cement products with different performance requirements. The product fineness is ground to the specific surface area. 330m ² /kg.

The content and scope of the present invention are not limited to the above-mentioned embodiments, and those skilled in the art can deduce other embodiments within the technical guidance 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 co-producing sulfuric acid and cement clinker by using sulfur gas as a reducing agent to reductively decompose gypsum to produce Belite sulfoaluminate cement without using other reducing agents such as solid coke, activated carbon and anthracite. Or gas CO, H ₂ , etc., without using other calcareous raw materials, to maximize the utilization of industrial waste gypsum, low-grade bauxite, coal gangue, red mud, fly ash and other resources, and to obtain a wide source of raw materials, reduce carbon emissions Emission, increase the concentration of SO ₂ in the furnace gas, improve production efficiency, reduce energy consumption and production costs and other social and economic benefits.

Claims (8)

1. A method for preparing belite sulphoaluminate cement and co-producing sulfuric acid by reducing gypsum by sulfur gas is characterized in that industrial by-product gypsum is used as a main raw material, one or more of low-grade bauxite, fly ash, coal gangue, red mud, clay and iron slag are selected as auxiliary materials by controlling alkalinity coefficient (C), aluminum-sulfur ratio (P) and aluminum-silicon ratio (N) according to the application requirements of belite sulphoaluminate cement clinker, and gas sulfur is used as a reducing agent to promote gypsum decomposition to prepare belite sulphoaluminate cement, and high-concentration gas-phase SO is obtained simultaneously₂The flue gas is used for preparing sulfuric acid from the subsequent flue gas;

the method specifically comprises the following steps:

A. preparation of gaseous sulfur

Heating and melting solid or liquid sulfur into crude sulfur liquid, filtering to obtain refined sulfur liquid, gasifying to obtain high-temperature gas sulfur, and feeding the gas sulfur into a reduction furnace through a Venturi ejector;

B. ingredients

Mixing and homogenizing dehydrated gypsum obtained after industrial byproduct gypsum is dehydrated and ingredients in a mixer, and further homogenizing in a homogenizing warehouse to obtain raw materials with uniform components; the raw materials are proportioned by taking the ratio of the raw materials as alkalinity coefficient C of 0.92-0.98, aluminum-sulfur ratio P of 0.95-3.82 and aluminum-silicon ratio N of 0.42-3.20, and the raw materials meet the above ratio, wherein the raw materials comprise, by weight, 65-95 parts of gypsum, 0-25 parts of bauxite, 0-15 parts of fly ash, 0-30 parts of coal gangue, 0-30 parts of red mud, 0-30 parts of clay and 0-8 parts of iron slag, and the gypsum is dihydrate gypsum or hemihydrate gypsum; the bauxite is one of low-grade bauxite or high-grade bauxite, and Al of the bauxite is₂O₃The mass fraction is 30-75%;

C. pre-heating pre-reduction

Raw meal is sent into a multistage suspension preheating system for step preheating, wherein 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 first-stage cyclone preheater together with hot air flow, and then cascade mass transfer, preheating and separation are completed within 20-60 seconds through the lower-layer cyclone preheaters in sequence; and (B) the preheated raw material enters a reducing furnace to perform a reduction reaction with the sulfur gas entering the reducing furnace in the step A, wherein the reduction reaction in the reducing 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 the sulfur gas entering the reduction furnace to the sulfur in the calcium sulfate in the raw material is (0.1-0.7): 1, (2) the molar ratio of the calcium sulfide in the raw material discharged from the reduction furnace to the CaSO in the raw material₄The 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; the reacted 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 enter a rotary kiln;

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 material at high temperature after deep reduction to form belite 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 material temperature after deep reduction is 950-1150 ℃, 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 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 the combined material into the cement clinker from the cooler in the step E, and then carrying out subsequent grinding processing to obtain the belite sulphoaluminate cement products with different performance requirements.

2. The method for preparing belite sulphoaluminate cement and co-producing sulfuric acid by sulfur gas reduction gypsum according to claim 1, wherein the solid or liquid sulfur in the step A is introduced into a sulfur melting tank and is indirectly heated to 120-160 ℃ by steam or heat transfer oil or electricity to be melted into crude sulfur liquid, and the fine sulfur liquid is sent into a gasification furnace to be heated and gasified to 450-900 ℃ to prepare high-temperature gas sulfur.

3. The method for preparing belite sulphoaluminate cement and co-producing sulfuric acid from sulfur gas reduction gypsum according to claim 1, wherein the industrial byproduct gypsum dehydration in the step B is drying dehydration 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 high-temperature surplus air discharged by a cooler, a heat source obtained by recovering the waste heat of flue gas at the outlet of a first-stage cyclone preheater and a heat source obtained by recovering the low-temperature waste heat in the co-production sulfuric acid; the bauxite adopts low-grade bauxite and Al thereof₂O₃The mass fraction is 30-55%;

the industrial by-product gypsum is a calcium and sulfur material containing calcium sulfate, and comprises at least one or more of phosphogypsum, desulfurized gypsum, salt gypsum, titanium white by-product gypsum, fluorgypsum, nickel gypsum and manganese gypsum.

4. The method for preparing belite sulphoaluminate cement and co-producing sulfuric acid by sulfur gas reduction gypsum according to claim 1, wherein the multistage suspension preheating system of step C comprises 4-6 stages of cyclone preheaters, each cyclone preheater is single-row or double-row, and the material flow is single-row series or two-row cross series;

and the flue gas separated by the cyclone separator enters a multistage suspension preheater, and the separated solid material is pre-reduced raw material with the temperature of 700-950 ℃.

5. The method for preparing belite sulphoaluminate cement and co-producing sulfuric acid by sulfur gas reduction gypsum according to claim 4, wherein the reduction furnace is a gas-solid co-flow type transport bed reduction reaction furnace, and is a single-pass type transport bed reactor or an external circulation type transport bed reactor with an external separator;

the bottom of the reducing furnace is provided with a combustion chamber, fuel of the reducing furnace adopts one or the combination of two of liquid sulfur and gas sulfur from the step A, the combustion chamber supplies heat required by the pre-reduction of calcium sulfate, a high-temperature flue gas part out of the rotary kiln enters the reducing furnace through the combustion chamber, and the rest part directly enters the reducing furnace through a bypass; part of the oxygen required by the combustion chamber comes from oxygen brought by the flue gas of the rotary kiln, and the other part of the oxygen is discharged by a supplementary cooler;

the outlet flue of the cyclone separator is set to be an oxygen supplementing combustion chamber, supplementing air is used for consuming residual gas sulfur in flue gas, the oxygen content in the flue gas at the outlet of the topmost cyclone preheater is detected and controlled to be 0-1.5% v/v to adjust and control the amount of air supplemented into the combustion chamber, it is ensured that the tail gas at the outlet of the topmost cyclone preheater does not contain elemental sulfur, the air supplemented by the combustion chamber adopts hot air exhausted by a cooler, and the temperature of the flue gas at the outlet of the topmost cyclone preheater is controlled to be 200-400 ℃.

6. The method for preparing belite sulphoaluminate cement and co-producing sulfuric acid by sulfur gas reduction gypsum according to 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, wherein the two rotary kilns connected in series are a reduction rotary kiln and a sintering rotary kiln.

7. The method for preparing belite sulphoaluminate cement and co-producing sulfuric acid from sulfur gas reduction gypsum according to claim 1, wherein the high temperature cement clinker from the rotary kiln of step E is cooled to room temperature-65 ℃ by heat exchange with air in a cooler;

the cooler is one of a grate cooler, a roller cooler and a vertical 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;

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.

8. The belite-sulphoaluminate prepared from sulfur gas reduction gypsum according to claim 1The method for the co-production of sulfuric acid by salt cement is characterized in that the mineral composition of the cement clinker from the cooler in the step F is C₄A₃

C₂S:30～70％，C₃S:0～50％，C₄AF:3～35％，

And others: 0 to 5 percent;

according to the content of high-temperature sintered gypsum in the cement clinker, determining that no or little gypsum and combined materials are doped by combining tests and calculation, and then performing subsequent grinding processing to meet the performance requirements of the belite sulphoaluminate cement product, wherein the fineness of the product is obtained by grinding the product until the specific surface area is 320-420 m²/kg；

The belite sulphoaluminate cement products comprise ordinary belite sulphoaluminate cement, high-iron belite sulphoaluminate cement, high-sulphur belite sulphoaluminate cement, high-silicon belite sulphoaluminate cement and high belite sulphoaluminate cement.

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