WO2017173716A1 - 一种磷石膏分解气联合湿法磷酸生产的方法 - Google Patents

一种磷石膏分解气联合湿法磷酸生产的方法 Download PDF

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WO2017173716A1
WO2017173716A1 PCT/CN2016/083229 CN2016083229W WO2017173716A1 WO 2017173716 A1 WO2017173716 A1 WO 2017173716A1 CN 2016083229 W CN2016083229 W CN 2016083229W WO 2017173716 A1 WO2017173716 A1 WO 2017173716A1
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phosphoric acid
slurry
gas
wet
phosphate
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龚家竹
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成都千砺金科技创新有限公司
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/69—Sulfur trioxide; Sulfuric acid
    • C01B17/74—Preparation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/22—Preparation by reacting phosphate-containing material with an acid, e.g. wet process
    • C01B25/222—Preparation by reacting phosphate-containing material with an acid, e.g. wet process with sulfuric acid, a mixture of acids mainly consisting of sulfuric acid or a mixture of compounds forming it in situ, e.g. a mixture of sulfur dioxide, water and oxygen

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  • the invention relates to the field of resource reuse of phosphogypsum, in particular to a method for producing phosphogypsum decomposition gas combined with wet process phosphoric acid.
  • Phosphogypsum is the main solid waste for the production of high-concentration phosphate fertilizer. China's phosphorus chemical production ranks first in the world. In 2015, China's wet-process phosphoric acid production was about 15 million tons (P 2 O 5 %), and by-product phosphogypsum was 80 million tons. At the same time, it needs to consume 40 million tons of sulfuric acid, ranking first in the world.
  • the current treatment method generally uses the reduction and decomposition of phosphogypsum to produce sulfuric acid for the recycling of wet-process phosphoric acid, which can reduce the solid waste heaping of phosphorus gypsum and the sulfur-saving resources of the wet-process phosphorus chemical industry. It is an advantageous way to solve the solid waste discharge of phosphorus chemical industry; the chemical reaction of decomposition of phosphogypsum is as follows:
  • each mole of sulfur oxide gas contains 1/2 of carbon dioxide, and in order to reach the decomposition temperature, it is burned with a non-sulfur substance (such as carbon) to provide heat, which not only causes gas composition.
  • a non-sulfur substance such as carbon
  • the sulfuric acid used for the raw material of the wet process phosphoric acid is oxidized to produce SO 2 gas by using a sulfur-containing raw material such as pyrite or sulfur and calcination and combustion through oxygen in the air, and the production principle is as follows:
  • the SO 3 gas obtained by catalytic oxidation is absorbed by water to obtain sulfuric acid, and the production principle is as follows:
  • the early sulfuric acid production adopts a one-time conversion and one absorption (ie “one-to-one-suction”) process, and the production process is simple, not only the equipment investment is low, but also the operating cost is low; but according to the reaction formula (4) (5)
  • the conversion rate and absorption rate are low, the total conversion rate of sulfur oxide is only 95%, about 5% of the exhaust gas SO 2 content is excluded, and the acid mist is heavy (including SO 3 high), which is almost completely eliminated.
  • Modern sulfuric acid production is also based on the production principle of reaction formula (4) (5), using two-stage multi-stage conversion and two absorption (ie “primary absorption” and “last absorption”) so-called “two-rotation two-suction” process
  • the purpose of taking sulfuric acid is to increase the conversion efficiency of the reaction (4) after two stages of catalytic conversion of SO 2 produced by combustion, and the purpose of the two absorptions is to increase the converted SO 3 gas with concentrated sulfuric acid.
  • the absorption efficiency, the total conversion rate of sulfur oxides reached 99.2%.
  • the reduction and decomposition of phosphogypsum to produce sulfuric acid sulfur resources recycling production equipment the largest investment is sulfuric acid plant, the cost of the device includes four items: one is the purification device of phosphorus gypsum reduction and decomposition gas, dust removal, pickling or water washing;
  • the two-stage multi-stage conversion unit for the oxidation of sulfur dioxide to sulfur trioxide is increased in size and the amount of catalyst is increased;
  • the third is the increase in the size of the absorption tower unit for two absorptions; and the fourth is that the tail gas also needs to be treated for the desulfurization unit.
  • the investment cost is increased, the production operation cost is increased, especially the power of the sulfuric acid fan brought by the system resistance is increased, and the production cost is reflected in the increase of the electricity cost;
  • the cost is higher than the production cost of other sulfur resources, which is not conducive to the production of sulfur-cycle phosphorus chemical for the decomposition of acid gypsum.
  • the inventor successfully applied the phosphate and calcium phosphate in the phosphate rock to react with sulfuric acid and phosphoric acid in the wet process phosphoric acid in the patent No. ZL94111776.6 (patent name: a method for producing phosphoric acid and a phosphorus-containing solution by a sulfuric acid method).
  • the principle solves the problem of high consumption of sulfuric acid and lime in the production of feed phosphate by wet-process phosphoric acid, greatly reduces the amount of sulfuric acid and lime raw materials, and lays a domestically produced feed phosphate production technology.
  • patent number ZL201310437466.3 patent name: a gypsum production method for joint production of sulfuric acid
  • patent number ZL201410069087.8 patent name: high silicon phosphate production
  • patents such as phosphoric acid by-product of low-silicon phosphogypsum, the calcium and silicon elements in the phosphate rock have been indirectly or directly subjected to cyclic economic processing or resource utilization.
  • phosphogypsum is used as a resource for recycling wet-phosphorus chemical production.
  • the practical problems of sulfur resource recycling and non-phosphorus gypsum discharge have urgently needed to develop sustainable advanced
  • the production technology meets the needs of human survival and production, and achieves the harmonious unity of “Jinshan Yinshan and Green Water Mountain”.
  • a method for producing a phosphogypsum decomposition gas in combination with a wet process phosphoric acid comprising the steps of:
  • the tail gas A obtained in the step (2) is pre-decomposed and chemically absorbed by the phosphate rock slurry obtained in the step (1) to obtain tail gas B and a sulfuric acid-containing phosphorus slurry, and the tail gas B is discharged.
  • the phosphorus slurry containing sulfuric acid is sent to a wet phosphoric acid production unit as a raw material feed.
  • the phosphogypsum decomposition gas is directly absorbed by the phosphate slurry prepared by the wet process phosphoric acid by the conventional one-by-one-extracted tail gas A, and the sulfur dioxide in the tail gas A is converted into the phosphate pulp.
  • the pre-decomposition uses sulfuric acid, so that the absorbed phosphate slurry can be directly used as the raw material of the wet-process phosphoric acid, that is, the one-by-one-suction exhaust gas treatment and the wet-process phosphoric acid extraction process are combined into one, and the "one stone and two birds"
  • the innovative effect, the reaction principle is:
  • the calcium sulfite in the precalcined slurry is oxidized
  • the final stage absorption (if secondary absorption is used, then the "last stage absorption” means “secondary absorption") reaction such as reaction formula (6)-(9)
  • the carbonate in the phosphate rock and the lower SO 3 and SO 2 in the absorbed tail gas form sulfate and sulfite, emit CO 2 gas, to the primary absorption (or “first absorption”) due to carbon in the exhaust gas
  • the acid salt is reduced, and the higher SO 3 and SO 2 in the tail gas react with the phosphate rock to form a mixture of calcium dihydrogen phosphate salt and calcium fluoride precipitate according to the reaction formulas (10) and (11), and calcium dihydrogen phosphate in the solution.
  • Free calcium ions are easily reacted with sulfur oxides to form calcium sulfate, so that SO 3 and SO 2 in the sulfuric acid production tail gas are almost completely absorbed; the absorbed phosphate slurry is generated by the reaction formula (14) under the action of air.
  • Calcium sulphate, along with the unreacted phosphate slurry, is subjected to an extraction process of wet-process phosphoric acid, and wet sulphuric acid production is carried out as it is with sulfuric acid, regrind and return phosphoric acid.
  • the absorber can be used in single-stage, two-stage and multi-stage series and parallel;
  • the liquid-solid ratio of the phosphate slurry is in the range of 1:1-5, preferably 1:2-3, the temperature is normal temperature, and the fineness is It is over 80-200 mesh;
  • the original concentration of SO 2 that enters the absorber from one sulfur to one sulfuric acid is not limited, preferably less than 1%;
  • the gas inlet temperature is 60-100 ° C, preferably ⁇ 80 ° C;
  • the reaction temperature of the phosphorus slurry is 30-85 ° C, preferably 50-70 ° C;
  • the tail gas temperature of the final absorber is 60-80 ° C, preferably ⁇ 60 ° C, and the volume concentration of SO 2 in the excluded gas is ⁇ 100 PPM.
  • the technical solution of the present invention can be used for the treatment of the decomposition gas of phosphogypsum, and can also be used for the tail gas treatment after one-shot and one suction in the conventional sulfuric acid preparation process, or the treatment with sulfur dioxide tail gas from other sources.
  • the liquid to solid mass ratio of the phosphate rock slurry obtained in the step (1) is 1: (1-5), preferably 25-40%; and the granular fineness of the phosphate rock slurry is 80-250 mesh.
  • the liquid:solid mass ratio of the phosphate rock slurry obtained in the step (1) is 1: (2-3); and the granular fineness of the phosphate rock slurry is 120-150 mesh.
  • the concentration of SO 2 in the tail gas A is 3% or less, and the temperature at which the tail gas A enters the phosphate slurry in the step (3) is lower than 100 ° C.
  • the concentration of SO 2 in the exhaust gas A is 1.5% or less, and the temperature at which the tail gas A enters the phosphate slurry in the step (3) is 60-80 ° C.
  • the pre-decomposition and chemical reaction absorption described in the step (3) is one stage, two stages or at least three stages.
  • the absorption mode described in the step (3) is a countercurrent, cocurrent or countercurrent cocurrent mixing absorption.
  • the pre-decomposition and chemical reaction absorber can be made into single-stage, double-pole and multi-stage according to the change of exhaust sulfur oxide, and the single, double and multi-stage absorbers can be connected in series and in parallel to form a whole;
  • the device can be a conventional countercurrent, cocurrent and countercurrent cocurrent mixing absorber, or a dynamic wave absorber produced by the existing two-rotation two-suction process sulfuric acid;
  • the phosphorus slurry may be added all from the last stage, or may be added separately from each stage.
  • the decomposed and absorbed slurry may be discharged from the first stage or from each stage to the absorption slurry collection tank.
  • the original concentration of SO 2 entering the absorber is not limited, preferably 1% or less; the gas inlet temperature is 60-100 ° C, preferably 80 ° C; the circulating phosphorus slurry reaction temperature is 30- 85 ° C, preferably 50 to 70 ° C; the final stage absorber temperature of 60-80 ° C, preferably 60 ° C.
  • the invention has the advantages that: the phosphate gypsum decomposition gas is decomposed and absorbed by using the one-turn-and-absorbed treatment gas, and the phosphogypsum decomposition gas only needs to adopt a simple one-turn-and-sucking process.
  • the process is shortened, the investment of the device is reduced, and the corresponding disadvantages of the conventional two-rotation and two-suction treatment are overcome; the power consumption is saved, the production cost is reduced; the SO 2 emission is reduced, and the SO 2 emission concentration is reduced.
  • sulfur element can be returned to the production of phosphate fertilizer and wet process phosphoric acid, which improves the utilization rate of sulfur resources; obtains good environmental benefits while obtaining significant economic benefits; provides a kind of sulfuric acid for low concentration SO 2 production.
  • the most simple and practical production method and process route, especially suitable for the optimal economic production method of sulfur resource recycling of sulfuric acid and cement for solid waste phosphogypsum, is an effective way to maximize the circular economy and maximize the utilization of resources. . It has achieved the advantages of increasing production, protecting the environment, saving energy, reducing costs, improving efficiency, reducing investment, increasing the economic efficiency of producers, and achieving significant economic and social benefits.
  • Figure 1 is a process flow diagram of the present invention.
  • a method for producing phosphogypsum decomposition gas combined with wet process phosphoric acid as shown in Fig. 1, in this embodiment, the secondary absorber 6 and the secondary circulation pump 7 do not participate in operation, and only single-stage absorption is performed.
  • the composition is shown in Table 1. It is sent to the phosphate rock tank 2 for storage.
  • the slurry pump 3 sends 20.0 tons/hour of phosphate slurry to the primary absorber 4, and the slurry is pumped into the primary absorber 4 by the primary circulation pump 5 for circulation, and the phosphogypsum decomposition gas is rotated one by one.
  • the sulfuric acid tail gas A (the composition thereof is shown in Table 2) is sent to the primary absorber 4 at a flow rate of 3218.6 Kmol/h; the chemical reaction is absorbed in the primary absorber 4, and the absorption reaction is completed.
  • the flow rate of the exhaust gas B1 (see Table 3) is 3703.5Kmol/h, and its concentration is lower than the national emission standard of the two two-stage two-stage conversion, which is below 300PPM; the absorption is absorbed from the absorber 4 every hour.
  • the phosphorus slurry after sulfur dioxide was 14.2 ton / hr (the composition of which is shown in Table 4), and the wet process phosphoric acid production process was sent as a raw material for the phosphate slurry feed.
  • Table 1 Composition table of phosphate rock and phosphate slurry (mass percentage)
  • a method for producing phosphogypsum decomposition gas combined with wet process phosphoric acid as shown in Fig. 1, quantitatively adding phosphate rock to mill 1, adding a certain amount of water, and grinding into a phosphate slurry having a solid content of 35%, the composition of which is shown in Table 5, the particle fineness is 120 mesh, sent to the phosphate slurry tank 2 for storage, the phosphate slurry pump 3 is used to send 30.0 tons / hour of phosphate slurry to the secondary absorber 6, and the slurry is pumped by the secondary circulation pump 7.
  • the secondary absorber 6 Pumped into the secondary absorber 6 for circulation, and with the exhaust gas B1 containing the SO 2 concentration of about 300-320 PPM from the primary absorber 4, the secondary absorber 6 is in countercurrent contact and circulation with the phosphate slurry, resulting in countercurrent contact and circulation.
  • the phosphorus slurry removed from the bottom of the absorber 6 is sent to the feed pipe of the primary circulation pump 5, and pumped into the primary absorber 4 for circulation.
  • One turn and one sulfuric acid tail gas A (the composition thereof is shown in Table 6), and the tail gas A sent from one sulfuric acid sulfuric acid production is sent to the primary absorber 4, and the flow rate of the gas A is 4338.392 Kmol/h.
  • the excluded gas B1 is sent to the secondary absorber 6 for secondary absorption as described above; the flow rate of the phosphorus slurry after the bottom is removed to absorb the sulfur oxide is 20.48 tons/hour.
  • the composition is shown in Table 8, and the wet process phosphoric acid production is sent as a raw material for the phosphate slurry feed.
  • a method for producing phosphogypsum decomposition gas combined with wet process phosphoric acid as shown in Fig. 1, quantitatively adding phosphate rock to the mill 1, adding a certain amount of water, grinding into a phosphate slurry having a solid content of 30%, and the particle fineness is 120 mesh, its composition is shown in Table 9, sent to the phosphate slurry tank 2 for storage, and the phosphate slurry pump 3 is used to quantitatively send 40.0 tons / hour to the secondary absorber 6, after the secondary absorption circulation pump 7 is started,
  • the gas B1 containing the SO 2 concentration of about 150-100 PPM is discharged from the primary absorber 4 in countercurrent contact with the phosphate slurry, and is subjected to chemical reaction absorption in the secondary absorber 6 ; the concentration of sulfur oxide in the absorbed gas B is lower than 100 PPM (the composition of which is shown in Table 11) was excluded from the top of the absorber 6, and the flow rate of the gas B was 6630.1662 Kmol/h.
  • the sulphur-absorbing phosphorus slurry removed from the bottom of the absorber 6 is used as a feed for the primary circulation pump 5 in the primary absorber 4.
  • one turn A sulfuric acid tail gas A (the composition thereof is shown in Table 10) is sent to the primary absorber 4, and the flow rate of the tail gas A is 5252.9619 Kmol/h.
  • the excluded gas B1 is sent to The second-stage absorption is performed in the second-stage absorber 6; the flow rate of the phosphorus slurry after absorbing the sulfur oxide is 23.68 tons/hour at the bottom, and the composition thereof is shown in Table 12, and the wet-process phosphoric acid is sent to be used as the raw material of the phosphate slurry.

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Abstract

提供一种磷石膏分解气联合湿法磷酸生产的方法，包括：将磷矿经过湿法研磨得到磷矿浆；磷石膏分解气经过一转一吸工艺后，得到含SO 2的尾气A；将尾气A用磷矿浆进行预分解和化学反应吸收，得到尾气B和含硫酸的磷料浆，含硫酸的磷料浆作为湿法磷酸生产装置的原料进料。该方法中磷石膏分解气仅需要采用简单的一转一吸工艺，SO 2的排放浓度就可以低至40ppm以下，提高了硫的资源利用率；具有清洁生产、保护环境、节约能源等优点。

Description

一种磷石膏分解气联合湿法磷酸生产的方法 技术领域
本发明涉及磷石膏的资源再利用领域，尤其涉及一种磷石膏分解气联合湿法磷酸生产的方法。
背景技术
磷石膏是高浓度磷肥生产的主要固体废物，我国磷化工产量已居世界第一位，2015年我国湿法磷酸生产约1500万吨(P2O5％)，副产磷石膏8000万吨，同时需要消耗硫酸产量4000万吨，位居世界第一位。
为了解决磷石膏大量堆积的问题，目前的处理方法一般是将磷石膏采用还原分解生产硫酸用于湿法磷酸的循环利用，这样可以减少湿法磷化工的磷石膏固废堆放和节约硫资源，是解决磷化工固废排放的有利途径；磷石膏分解的化学反应如下：
CaSO4+2C＝CaS+2CO2↑    (1)
3CaSO4+CaS＝4CaO+4SO2↑    (2)
按反应式(1)和(2)每1分子氧化硫气体中含有1/2的二氧化碳，且为了达到分解的温度还要以非硫物质(如碳)燃烧以提供热量，不仅造成气体组成的差异，且氧化硫浓度相对较低。
上述的磷石膏还原分解产生的氧化硫气体组成与传统的采用硫 铁矿和硫磺焙烧或燃烧的氧化硫组成存在较大的差异。
具体而言，用于湿法磷酸生产原料的硫酸，是采用含硫原料如硫铁矿、硫磺经过空气中的氧进行焙烧与燃烧而氧化产生出SO2气体，其生产原理为：
S+O2＝SO2    (3)
产生的氧化硫气体再经过接触催化氧化将SO2转化成SO3，其生产原理为：
2SO2+O2＝2SO3    (4)
催化氧化得到的SO3气体用水吸收得到硫酸，其生产原理为：
2SO3+H2O＝H2SO4    (5)
按此生产原理，早期的硫酸生产采用一次转化一次吸收(即“一转一吸”)工艺方法，生产流程简单，不仅装置投资低，而且运行生产费用低；但按反应式(4)(5)进行的转化率与吸收率低，氧化硫的总转化率仅有95％，约有5％排除的尾气SO2含量高，酸雾重(含SO3高)，几乎被全部淘汰。现代的硫酸生产同样按反应式(4)(5)的生产原理，采用两次多段转化与两次吸收(即“初级吸收”和“末级吸收”)的所谓“两转两吸”工艺制取硫酸，其目的是将燃烧生成的SO2经过两次多段催化转化成后，提高反应(4)式的转化效率，而两次吸收的目的同样是用浓硫酸提高转化后的SO3气体的吸收效率，其氧化硫的总转化率达到99.2％。几乎达到国家尾气排放标准的800mg/m3，但因雾霾与环保的严峻形势，2015年国家尾气标准下降到400mg/m3,现有硫酸装置需要配套尾气脱硫装置。
因此，磷石膏还原分解产生的氧化硫气体若采用传统的“两转两吸”工艺生产硫酸，对比硫铁矿与硫磺焙烧与燃烧产生的氧化硫具有较大的差别与不足，存在的主要缺点如下：
一、因反应式(1)生产的二氧化碳气体的存在，氧化硫浓度相对较低且不稳定，在反应式(4)中的转化温度不够，影响反应速度，致使生产能力下降，需要配置电炉对气体进行加热升温，增加投资与生产费用；
二、磷石膏还原分解生产硫酸的硫资源循环生产装置中，投资最大的是硫酸装置，其装置费用包括4项：一是磷石膏还原分解气体的净化装置，除尘、酸洗或水洗；二是二氧化硫氧化成三氧化硫的两次多段转化装置规格增大与催化剂的用量增高；三是两次吸收的吸收塔装置规格增大；四是尾气同样需要进行脱硫装置的治理费用。
三、由于“两转两吸”装置规格的增大，投资费用增高，生产运行费用增加，尤其是系统阻力带来的硫酸风机功率增大，其生产成本体现在电费的增加；造成单位硫酸生产成本高于其它硫资源的生产成本，不利于磷石膏分解制酸的硫循环磷化工生产。
发明人在专利号ZL94111776.6(专利名称：一种硫酸法生产磷酸及含磷溶液的方法)，成功应用了磷矿中碳酸盐和磷酸钙能与湿法磷酸中的硫酸和磷酸发生反应的原理，解决了湿法磷酸生产饲料磷酸盐的硫酸与石灰消耗高的问题，大幅度减低了硫酸与石灰原料的用量，并奠定了今天具有国内独创的饲料磷酸盐生产技术。其后在专利号ZL97107676.6，(专利名称：利用湿法磷酸盐废渣生产磷酸铵肥料 的方法)，经济的解决了饲料磷酸盐脱氟渣作为肥料磷酸铵及复混肥基础磷源肥料的生产难题，使饲料磷酸盐生产企业获得了巨大的经济与社会效益。作为磷矿资源全利用的生产开发，发明人又在专利号ZL201310437466.3(专利名称：一种石膏生产水泥联产硫酸的生产方法)和专利号ZL201410069087.8(专利名称：高硅磷矿生产磷酸副产低硅磷石膏的方法)等发明专利中已间接或直接的将磷矿中钙元素和硅元素进行循环经济加工或资源化利用。
中国专利申请(CN10467728)“一种脱出硫酸尾气中二氧化硫的方法”，采用20-60％磷矿浆将“两转两吸”硫酸生产尾气中二氧化硫由800mg/m3降到100mg/m3以下，吸收二氧化硫的磷矿浆用于磷矿反浮选脱镁工序的原料。该方法正如现有热电厂采用石灰脱出烟气中的二氧化硫一样，仅是将磷矿浆代替石灰浆对低含量二氧化硫气体进行吸收，且吸收二氧化硫的量相对较少，且仅用于磷矿选矿原料；未能的解决湿法磷酸生产硫资源的循环与硫酸装置昂贵的投资与生产费用问题。
作为磷石膏还原分解氧化硫气体用于现有硫酸生产，若采用两次多段转化和两次吸收，因氧化硫组成的差异，需要在转化时增加电炉供热，不仅生产装置投资大，生产运行费用也高，尾气同样需要治理。
随着环保要求的日益提高和磷化工可持续发展生成技术要求，磷石膏作为资源循环利用的湿法磷化工生产，硫资源的循环与无磷石膏排放的现实问题已迫切需要开发可持续的先进生产技术，满足人类生存和生产需要，做到“金山银山与绿水青山”的和谐统一。
发明内容
本发明的目的就在于提供一种磷石膏分解气联合湿法磷酸生产的方法，以解决上述问题。
为了实现上述目的，本发明采用的技术方案是这样的：一种磷石膏分解气联合湿法磷酸生产的方法，包括以下步骤：
(1)、将磷矿经过湿法研磨制备得到磷矿浆；
(2)、磷石膏分解气经过一转一吸工艺后，得到含SO2的尾气A；
(3)、将步骤(2)所得的尾气A用步骤(1)所得的磷矿浆进行预分解和化学反应吸收，得到尾气B和含硫酸的磷料浆，所述尾气B进行排放，所述含硫酸的磷料浆送去湿法磷酸生产装置作为原料进料。
本发明将磷石膏分解气经过传统的一转一吸后的尾气A，直接采用拟用于湿法磷酸制备的磷矿浆进行一次或多次吸收，使尾气A中的二氧化硫转化为磷矿浆预分解用硫酸，从而使得经过吸收后的磷矿浆可以直接作为湿法磷酸的原料，也就是将一转一吸后尾气处理与湿法磷酸萃取工艺合二为一，起到“一石二鸟”的创新效果，其反应原理为：
磷矿浆中的碳酸盐与“一转一吸”二氧化硫尾气的吸收反应
SO2+CaCO3+2H2O＝CaSO3·2H2O↓+CO2↑    (6)
SO2+MgCO3+2H2O＝MgSO3·2H2O+CO2↑    (7)
SO3+CaCO3+2H2O＝CaSO4·2H2O↓+CO2↑    (8)
SO3+MgCO3+2H2O＝MgSO4·2H2O+CO2↑     (9)
磷矿浆中氟磷灰石与“一转一吸”二氧化硫尾气的吸收反应
6SO2+2Ca5F(PO4)3+18H2O＝6CaSO3·2H2O↓+3Ca(H2PO4)2+CaF2↓  (10)
6SO3+2Ca5F(PO4)3+18H2O＝6CaSO4·2H2O↓+3Ca(H2PO4)2+CaF2↓  (11)
SO2+Ca(H2PO4)2+3H2O＝CaSO3·2H2O↓+2H3PO4    (12)
SO3+Ca(H2FPO4)2+3H2O＝CaSO4·2H2O↓+2H3PO4    (13)
预分解料浆中的亚硫酸钙被氧化
2CaSO3·2H2O+O2＝2CaSO4·2H2O↓    (14)
用磷矿浆去逆流吸收一转一吸产生的二氧化硫尾气时，末级吸收(如果采用二级吸收，那么“末级吸收”即“二级吸收”)反应如反应式(6)-(9)，磷矿中的碳酸盐与已吸收尾气中较低的SO3和SO2生成硫酸盐和亚硫酸盐，放出CO2气体，到初级吸收(或“一级吸收”)因尾气中碳酸盐减少，而尾气中较高的SO3和SO2与磷矿反应按反应式(10)和(11)生成磷酸二氢钙盐和氟化钙沉淀的混合物，溶液中的磷酸二氢钙游离的钙离子极易与氧化硫反应生成硫酸钙，这样致使硫酸生产尾气中的SO3和SO2几乎被全部吸收掉；吸收后的磷矿浆在空气的作用下按反应式(14)生成硫酸钙，与未反应的磷矿浆一道进入湿法磷酸的萃取工序，与加入的硫酸、返浆和返磷酸按现有进行湿法磷酸生产。
本发明中吸收器可采用单级、两级和多级串联与并联；磷矿浆的液：固比在1：1-5的范围，最好是1：2-3，温度常温，细度是过80-200目；一转一吸硫酸生产尾气进入吸收器的SO2原始浓度不受限制，最好是1％以下；气体进口温度为60-100℃，最好是～80℃；循环磷料 浆反应温度为30-85℃，最好是50～70℃；末级吸收器的尾气温度60-80℃，最好是～60℃，排除气体中SO2体积浓度﹤100PPM。
当然，本发明的技术方案，除了可以用于磷石膏分解气的处理，也可以用于常规的硫酸制备过程中一转一吸后的尾气处理，或者其他来源的含有二氧化硫尾气的处理。
作为优选的技术方案：步骤(1)所得磷矿浆的液：固质量比为1：(1-5)，最好是25-40％；磷矿浆的颗粒细度为80-250目。
作为进一步优选的技术方案：步骤(1)所得磷矿浆的液：固质量比为1：(2-3)；磷矿浆的颗粒细度为120-150目。
作为优选的技术方案：所述尾气A中SO2体积百分浓度为3％以下，步骤(3)中尾气A进入磷矿浆的温度低于100℃。
作为进一步优选的技术方案：所述尾气A中SO2体积百分浓度为1.5％以下，步骤(3)中尾气A进入磷矿浆的温度为60-80℃。
作为优选的技术方案：步骤(3)所述的预分解与化学反应吸收为一级、两级或至少三级。
作为优选的技术方案：步骤(3)所述的吸收方式为逆流、并流或逆流并流混合吸收。
也就是说，所述预分解与化学反应吸收器可根据尾气氧化硫的变化作成单级、双极和多级，也可将单、双和多级吸收器进行串联和并联成一个整体；吸收器可为常规的逆流、并流和逆流并流混合吸收器，也可采用现有两转两吸工艺硫酸生产的动力波吸收器；
所述磷矿浆加入可全部从末级加入，也可分别从每一级加入，预 分解吸收后的料浆可从第一级出来，也可从每一级出来去到吸收料浆收集槽。
一转一吸硫酸尾气A进入吸收器的SO2原始浓度不受限制，最好是1％以下；气体进口温度为60-100℃，最好是80℃；循环磷料浆反应温度为30-85℃，最好是50～70℃；末级吸收器的尾气温度60-80℃，最好是60℃。
与现有技术相比，本发明的优点在于：由于采用磷矿浆对磷石膏分解气采用一转一吸处理后的尾气进行分解吸收，磷石膏分解气仅仅需要采用简单的一转一吸工艺，缩短了工艺、降低了装置投资，也就克服了采用传统的两转两吸进行处理的相应缺点；节约了电耗，降低了生产成本；减少了SO2的排放量，SO2的排放浓度可以达到40ppm以下，硫元素可回到磷肥与湿法磷酸生产中，提高了硫的资源利用率；获得好的环保效益同时、获得显著的经济效益；对于低浓度SO2生产硫酸提供了一种最为简单而实用的生产方法及工艺路线，特别适用于固体废物磷石膏生产硫酸与水泥的硫资源循环的最优经济生产方法，不失为一个最佳的循环经济方法和资源利用最大化的切实有效途径。达到了清洁生产、保护环境、节约能源、降低成本、提高效率、减少投资等增加生产者的经济效益目的及经济和社会效益十分显著等优点。
附图说明
图1为本发明的处理流程图。
图中：1、磨机；2、磷矿浆槽；3、磷矿浆泵；4、一级吸收器；5、一级循环泵；6、二级吸收器；7、二级循环泵；8、磷料浆槽；9、磷料浆泵。
具体实施方式
下面将结合附图对本发明作进一步说明。
实施例1
一种磷石膏分解气联合湿法磷酸生产的方法，如图1，本实施例中，二级吸收器6与二级循环泵7不参与运行，仅进行单级吸收。将磷矿加入到磨机1，加入水，研磨成含固量为40％的磷矿浆，颗粒细度150目，其组成见表1，送入磷矿浆槽2内贮存，用磷矿浆泵3将20.0吨/小时磷矿浆送到一级吸收器4，用一级循环泵5将浆料泵入一级吸收器4内进行循环，另外，将磷石膏分解气采用一转一吸处理后，将一转一吸硫酸尾气A(其组成见表2)送到一级吸收器4，流量为3218.6Kmol/h；在一级吸收器4内进行化学反应吸收，吸收反应完成后排放尾气B1(其组成见表3)的流量为3703.5Kmol/h，其浓度低于现有两次多段转化两次吸收的国家规定排放标准，在300PPM以下；每小时从吸收器4移走吸收二氧化硫后的磷料浆14.2吨/小时(其组成见表4)，送去湿法磷酸生产工序作为磷矿浆进料原料。
表1 磷矿及磷矿浆的组成表(质量百分比)
Figure PCTCN2016083229-appb-000001
Figure PCTCN2016083229-appb-000002
表2 一转一吸硫酸尾气A组成表
成分 SO2 SO3 O2 CO2 H2O N2 合计
体积％ 0.32 0.04 8.99 5.59 0 85.02 100
Kmol/h 11.2 1.3 289.6 180 0.5 2736 3218.6
表3 排放尾气B1组成表
Figure PCTCN2016083229-appb-000003
表4 吸收氧化硫的磷料浆组成(质量百分比)
Figure PCTCN2016083229-appb-000004
实施例2
一种磷石膏分解气联合湿法磷酸生产的方法，如图1，将磷矿定量加入到磨机1，加入定量的水，研磨成含固量为35％的磷矿浆，其组成见表5，颗粒细度为120目，送入磷矿浆槽2内贮存，用磷矿浆泵3将30.0吨/小时磷矿浆送到二级吸收器6，用二级循环泵7将料浆泵入二级吸收器6内进行循环，并与从一级吸收器4排除送来含SO2浓度约300-320PPM的尾气B1在二级吸收器6与磷矿浆进行逆流接触与循环，产生化学反应吸收；被吸收后的尾气B中的氧化硫浓度低于100PPM，其组成见表7，流量为5178.42Kmol/h，从吸收器6顶部排除。从吸收器6底部排除的磷料浆送入一级循环泵5的进料管中，并泵入一级吸收器4中进行循环，另外，将磷石膏分解气采 用一转一吸处理后，将一转一吸硫酸尾气A(其组成见表6)，并将一转一吸硫酸生产送来的尾气A送入一级吸收器4中，气体A的流量为4338.392Kmol/h，在一级吸收器4内逆流循环接触进行化学反应吸收后，排除的气体B1送到二级吸收器6中按前述进行二级吸收；底部排除吸收氧化硫后的磷料浆流量为20.48吨/小时，其组成见表8，送去湿法磷酸生产作为磷矿浆进料原料。
表5 磷矿浆组成表
Figure PCTCN2016083229-appb-000005
表6 一转一吸硫酸生产尾气A组成表
成分 SO2 SO3 O2 H2O N2 合计
体积％ 0.3872 0.0464 5.3758 0.0141 94.1765 100
Kmol/h 16.8 2.016 233.2235 0.6149 4085.7376 4338.392
表7 排放尾气B组成表
Figure PCTCN2016083229-appb-000006
表8 吸收氧化硫的磷料浆组成
Figure PCTCN2016083229-appb-000007
实施例3
一种磷石膏分解气联合湿法磷酸生产的方法，如图1，将磷矿定量加入到磨机1，加入定量的水，研磨成含固量为30％的磷矿浆，颗粒细度为120目，其组成见表9，送入磷矿浆槽2内贮存，用磷矿浆泵3定量将40.0吨/小时送到二级吸收器6，在二级吸收循环泵7启动后，将从一级吸收器4排出含SO2浓度约150-100PPM气体B1与磷矿浆进行逆流接触，在二级吸收器6内进行化学反应吸收；被吸收后的气体B中的氧化硫浓度低于100PPM(其组成见表11)，从吸收器6顶部排除，气体B的流量为6630.1662Kmol/h。从吸收器6底部排除的吸收硫后的磷料浆作为一级吸收器4中配套的一级循环泵5的进料，另外，将磷石膏分解气采用一转一吸处理后，将一转一吸硫酸尾气A(其组成见表10)送入一级吸收器4中，尾气A的流量为5252.9619Kmol/h，在一级吸收器4内进行化学反应吸收后，排除的气体B1送到前述二级吸收器6中进行二级吸收；底部排除吸收氧化硫后的磷料浆流量为23.68吨/小时，其组成见表12，送去湿法磷酸生产作为磷矿浆进料原料。
表9 磷矿浆组成表
Figure PCTCN2016083229-appb-000008
表10 一转一吸硫酸尾气A组成表
成分 SO2 SO3 O2 H2O N2 合计
体积％ 0.43 0.05 5.89 ---- 93.63 100
Kmol/h 22.4 2.8402 309.3659 0.7575 4917.5983 5252.9619
表11 吸收后排放尾气B组成表
Figure PCTCN2016083229-appb-000009
表12 吸收氧化硫的磷料浆组成
Figure PCTCN2016083229-appb-000010
以上所述仅为本发明的较佳实施例而已，并不用以限制本本发明，凡在本本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本本发明的保护范围之内。

Claims (7)

  1. 一种磷石膏分解气联合湿法磷酸生产的方法，其特征在于，包括以下步骤：
    (1)、将磷矿经过湿法研磨制备得到磷矿浆；
    (2)、磷石膏分解气经过一转一吸工艺后，得到含SO2的尾气A；
    (3)、将步骤(2)所得的尾气A用步骤(1)所得的磷矿浆进行预分解和化学反应吸收，得到尾气B和含硫酸的磷料浆，所述尾气B进行排放，所述含硫酸的磷料浆送去湿法磷酸生产装置作为原料进料。
  2. 根据权利要求1所述的磷石膏分解气联合湿法磷酸生产的方法，其特征在于：步骤(1)所得磷矿浆的液：固质量比为1：(1-5)；磷矿浆的颗粒细度为80-250目。
  3. 根据权利要求2所述的磷石膏分解气联合湿法磷酸生产的方法，其特征在于：步骤(1)所得磷矿浆的液：固质量比为1：(2-3)；磷矿浆的颗粒细度为120-150目。
  4. 根据权利要求1所述的磷石膏分解气联合湿法磷酸生产的方法，其特征在于：所述尾气A中SO2体积百分浓度为3％以下，步骤(3)中尾气A进入磷矿浆的温度低于100℃。
  5. 根据权利要求4所述的磷石膏分解气联合湿法磷酸生产的方法，其特征在于：所述尾气A中SO2体积百分浓度为1.5％以下，步骤(3)中尾气A进入磷矿浆的温度为60-80℃。
  6. 根据权利要求1所述的磷石膏分解气联合湿法磷酸生产的方 法，其特征在于：步骤(3)所述的预分解与化学反应吸收为一级、两级或至少三级。
  7. 根据权利要求1所述的磷石膏分解气联合湿法磷酸生产的方法，其特征在于：步骤(3)所述的吸收方式为逆流、并流或逆流并流混合吸收。
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