WO2019100499A1 - 利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法 - Google Patents

利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法 Download PDF

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WO2019100499A1
WO2019100499A1 PCT/CN2017/117517 CN2017117517W WO2019100499A1 WO 2019100499 A1 WO2019100499 A1 WO 2019100499A1 CN 2017117517 W CN2017117517 W CN 2017117517W WO 2019100499 A1 WO2019100499 A1 WO 2019100499A1
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calcium
hydrochloric acid
phosphate
filtrate
salt
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English (en)
French (fr)
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李进
王佳才
邹建
吴生平
侯隽
黄恒
张希阳
张萍
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川恒生态科技有限公司
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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
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/32—Phosphates of magnesium, calcium, strontium, or barium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/46—Sulfates

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  • the invention belongs to the technical field of feed and fertilizer, and particularly relates to a method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphate rock.
  • Calcium phosphate salt can be used as fertilizer grade calcium phosphate salt, widely used in agricultural production, mainly used as raw material for compound fertilizer, and can also be directly applied to farmland; calcium phosphate salt can be used as feed grade calcium phosphate salt, suitable for Animals such as livestock and poultry, aquatic products, etc. are feed additives used to supplement calcium and phosphorus nutrition of livestock and poultry and aquatic animals.
  • China's phosphate rock must meet the demand of phosphoric acid and high-concentration phosphorus compound fertilizer production after mineral processing and rich ore; it is difficult to select more ore and easy to select minerals.
  • China's phosphate reserves There are many sedimentary phosphorus blocks (glylite mines), accounting for 85% of the country's total reserves, most of which are medium and low grade ore.
  • 90% of China's phosphate rock is high-magnesium phosphate, and its useful minerals in the ore are fine-grained. It is closely combined with gangue and is not easy to separate. It is one of the most difficult phosphate ore in China.
  • Patent CN105921259A discloses a method for producing feed grade calcium dihydrogen phosphate by using medium and low grade mixed phosphate rock, which seems to use medium and low grade phosphate rock as raw material, but actually the medium and low grade calcium magnesium phosphate rock ore is actually used.
  • the inhibitor and the collector are sequentially added to the slurry, and the flotation is reversed to obtain a phosphate concentrate which is further reacted with sulfuric acid.
  • most of the existing processes for producing calcium phosphate salt first convert calcium in phosphate rock into phosphogypsum (calcium sulfate with high impurity) as industrial waste, and the storage and digestion of phosphogypsum is a difficult point in the industry.
  • phosphogypsum calcium sulfate with high impurity
  • the technical problem to be solved by the present invention is to provide a method for producing calcium phosphate salt and high-purity gypsum using hydrochloric acid and phosphate rock.
  • the method includes the following steps:
  • the phosphate rock is not completely decomposed by hydrochloric acid having a mass concentration of 15% or less, and solid-liquid separation is carried out to obtain solid 1 and liquid 1; wherein, the mass ratio of solid 1 is P 2 O 5 /MgO>6;
  • liquid 1 is added with alkaline calcium salt to adjust the pH to 1.2 ⁇ 2.2, filtered to obtain filter cake 4 and filtrate 4;
  • the filtrate 4 is added with a basic calcium salt to adjust the pH to 4.8 to 6.2, and the filter cake 5 and the filtrate 5 are separated by filtration, and the filter cake 5 is calcium hydrogen phosphate;
  • filtrate 5 is added with basic calcium salt to adjust the pH to 9 ⁇ 11, filtered to obtain filter cake 6 and filtrate 6;
  • the filtrate 6 is reacted with sulfuric acid to obtain high purity gypsum and hydrogen chloride or hydrochloric acid.
  • the amount of sulfuric acid added is controlled to completely convert excess calcium into calcium sulfate; the excess calcium means phosphoric acid in filtrate 2. Calcium remaining after conversion of calcium to calcium dihydrogen phosphate.
  • step A of the method for producing a calcium phosphate salt and a high-purity gypsum using hydrochloric acid and phosphate rock sulfuric acid is added to carry out the reaction while maintaining the temperature at a temperature of 60 to 100 ° C.
  • the hydrochloric acid has a mass concentration of 5% or more. Further, the hydrochloric acid has a mass concentration of 20 to 30%.
  • the reaction temperature of the solid 1 and hydrochloric acid is from room temperature to 80 ° C.
  • the heating dechlorination, defluorination and dehydration are carried out by vacuum concentration, oven drying, atomization, disc or cylinder.
  • the basic calcium salt is at least one of lime or calcium carbonate.
  • the alkaline calcium salt is at least one of lime or calcium carbonate.
  • the alkaline calcium salt is at least one of quicklime or slaked lime.
  • the method of the invention comprises the calcium dihydrogen phosphate produced in the process step A, and the calcium hydrogen phosphate product is obtained in the process step B, and the two products are compounded and processed to obtain the monocalcium phosphate product, so the implementation of the process Three calcium phosphate salt products are available in one shot.
  • the calcium of the phosphate rock is completely converted into the ionic calcium, and the phosphoric acid in the step A can fully react with the ionic calcium, and no package is generated.
  • the calcium dihydrogen phosphate product has high purity and low free acid content, and subsequent The product is not easy to agglomerate and has excellent quality, meeting the requirements of GBT22548-2008 for feed grade calcium dihydrogen phosphate.
  • the method of the present invention can obtain two kinds of chemical gypsum, wherein the step B produces a high-purity gypsum containing phosphorus and fluorine, which can be further processed into a high-strength ⁇ -gypsum or whisker gypsum product, and is obtained by step A.
  • the gypsum can produce and process ⁇ -building gypsum, and the gypsum plaster can be prepared by mixing ⁇ and ⁇ gypsum to meet the needs of different customer markets.
  • Some (or all) of the phosphorus in the calcium phosphate salt prepared by the method of the present invention is derived from phosphorus in the phosphate rock, and this portion of P 2 O 5 is not obtained by preparing phosphoric acid by sulfuric acid, so that no difficult to treat phosphogypsum is produced. The emission of industrial waste is reduced, and the implementation of this process has extremely high social and economic benefits.
  • Step A of the method of the present invention accomplishes the four purposes of dechlorination, defluorination, dehydration and promotion of product production by heating one process, thereby improving production efficiency and achieving efficient production of calcium phosphate salt; and step A does not require defluorination.
  • the agent is chemically defluorinated to optimize the process and save costs.
  • the hydrochloric acid produced by the method of the invention can be closed and recycled, reduce tail gas emissions, does not cause environmental pollution, and reduces consumption of other production factors, and has extremely high economic and environmental benefits.
  • Figure 1 is a schematic diagram of the process flow of the method of the present invention
  • a method for producing calcium phosphate salt and high purity gypsum using hydrochloric acid and phosphate rock comprising the following steps:
  • the phosphate rock is not completely decomposed by hydrochloric acid having a mass concentration of 15% or less, and solid-liquid separation is carried out to obtain solid 1 and liquid 1; wherein, in mass ratio, P 2 O 5 /MgO>6 in solid 1; the purpose of this step is to remove phosphate rock Most of the magnesium and magnesium enter the liquid 1, which is equivalent to further purification of the phosphate rock, so that the obtained solid 1 contains less impurities, which is beneficial to the reaction of the filter cake to the step A to obtain high quality calcium dihydrogen phosphate; 1 contains Ca 2+ , H 2 PO 4 - , Cl - , F - , magnesium iron aluminum oxide;
  • the liquid calcium salt is added to the liquid 1 to provide a calcium source, and the pH of the system is adjusted to 1.2 to 2.2 to react the fluorine and calcium in the system to form CaF 2 to achieve the purpose of defluorination, and the filter cake 4 defluorination residue and filtrate are separated by filtration. 4;
  • the alkaline calcium salt is added to the filtrate 4 to provide a calcium source, and the pH of the system is adjusted to 4.8-6.2 to react the phosphate in the system with calcium to obtain calcium hydrogen phosphate precipitation, and the filter cake 5 and the filtrate 5 are separated by filtration, and the filter cake 5 is Calcium hydrogen phosphate, dry, collect the filter cake 5;
  • the filtrate 5 is added with alkaline calcium salt to adjust the pH to 9-11, so that the impurity magnesium ions in the system are precipitated as magnesium hydroxide, and at the same time, the purpose of removing a small amount of iron and aluminum ions in the system is obtained, and the filter cake is separated by filtration.
  • the raw material phosphate rock used is high impurity phosphate rock, phosphorus concentrate, high medium and low grade phosphate rock, and the active component is Ca 5 F(PO 4 ) 3 . It is generally accepted in the industry that P 2 O 5 is in the middle grade phosphate rock in 24-28%, low-grade phosphate rock in 18-24%, and high-grade phosphate rock in 28%.
  • the incomplete decomposition described in the incomplete decomposition of phosphate rock by hydrochloric acid means that when the phosphate is decomposed by hydrochloric acid, the phosphorus in the phosphate rock is not completely converted into acid-soluble phosphorus.
  • the factors affecting the degree of decomposition of phosphate rock by hydrochloric acid include the activity of phosphate rock, the particle size of phosphate rock, the reaction temperature, the reaction time, the ratio of hydrochloric acid to phosphate rock, etc.
  • the control of incomplete decomposition can be adjusted from several factors mentioned above.
  • the personnel can flexibly adjust, select and control the parameters such as particle size, reaction temperature time and raw material ratio of phosphate rock decomposition from any one or more of the above factors.
  • the parameters such as particle size, reaction temperature time and raw material ratio of phosphate rock decomposition from any one or more of the above factors.
  • it is also necessary to satisfy the mass ratio of P 2 O 5 /MgO in solid 1 to >6.
  • the significance of this design step is to remove the magnesium from the phosphate rock and improve the purity of the phosphate rock, which is conducive to improving the final product quality.
  • Controlling the mass concentration of hydrochloric acid to be 15% or less is to control the distribution ratio of phosphorus in the solid phase and the liquid phase in the incomplete acid hydrolysis reaction; controlling the mass ratio of P 2 O 5 /MgO to >6 is to ensure the dihydrogen phosphate obtained in the step A The quality of calcium products is qualified.
  • the solid-liquid separation is: separation of the system after incomplete decomposition of the phosphate rock by hydrochloric acid, separating the solid and the liquid, and adopting a conventional separation method in the art, such as filtration, thickening, and standing. , centrifugation, etc.
  • a conventional separation method in the art such as filtration, thickening, and standing. , centrifugation, etc.
  • the filter cake is the solid 1 of the invention
  • the filtrate is the liquid 1 of the invention; when it is thick, it can be thickened by a thickener, and thickened by a thickener.
  • the thick slurry is the solid 1 of the present invention
  • the clear liquid is the liquid 1 of the present invention
  • the lower layer slurry is the solid 1 of the present invention
  • the solid-liquid separation of the present invention can also be carried out by a combination of filtration, thickening, standing, centrifugation, etc., such as filtration after standing, thickening and filtration, etc., as long as the liquid and solid or slurry can be separated.
  • the decomposition of the phosphate rock in the solid 1 by hydrochloric acid is easy, and the normal concentration of hydrochloric acid is 20 to 30%, and the phosphate rock can be completely decomposed in a few minutes. Therefore, the concentration of the hydrochloric acid in the step A hydrochloric acid decomposition, the reaction temperature, and the reaction time are not particularly limited.
  • Low hydrochloric acid concentration can also decompose phosphate rock, but it is necessary to prolong the reaction time and / or increase the reaction temperature, and the amount of hydrochloric acid is increased, which is not conducive to the later dechlorination, defluorination, dehydration, increase equipment load and increase energy consumption;
  • the lower the reaction temperature the higher the concentration of hydrochloric acid is used and/or the reaction time is prolonged; however, the hydrochloric acid concentration, the reaction temperature, and the reaction time only affect the reaction efficiency, and have no effect on the quality of the obtained product itself. From the viewpoints of efficiency, economy, and the like, it is preferred that the mass concentration of hydrochloric acid is 5% or more. Further, the mass concentration of hydrochloric acid is 20 to 30%.
  • the reaction temperature is normal temperature, and the reaction temperature may be adjusted according to actual production requirements, such as controlling the reaction temperature to room temperature to 80 °C.
  • the purpose of adding sulfuric acid is to precipitate excess calcium in the filtrate 2, which is the calcium remaining after the conversion of phosphoric acid and calcium into calcium dihydrogen phosphate in the filtrate 2.
  • excess calcium in the filtrate 2 is the calcium remaining after the conversion of phosphoric acid and calcium into calcium dihydrogen phosphate in the filtrate 2.
  • the phosphoric acid and calcium in the filtrate 2 itself do not form calcium dihydrogen phosphate.
  • only part of the calcium is removed by theoretical calculation, and the remaining calcium is required to be added with sulfuric acid.
  • the reaction produces calcium sulfate.
  • the filtrate 2 obtained in the step A contains 3 mol of phosphoric acid and 5 mol of calcium chloride, and the product obtained by heating defluorination, dechlorination, and dehydration is calcium dihydrogen phosphate, and 3 mol of phosphoric acid is required to consume 1.5 mol.
  • Calcium there is still 3.5 mol of calcium remaining, and 3.5 mol of calcium here is an excess of calcium, and it is necessary to add 3.5 mol of sulfuric acid to react with an excess of 3.5 mol of calcium, so that the obtained product is calcium dihydrogen phosphate.
  • the above data are theoretical calculations. In the actual operation and reaction process, there may be some deviation. In fact, as long as the quality of the prepared product calcium phosphate salt is qualified.
  • the amount of calcium sulfate produced can be controlled according to the actual plant demand for calcium sulfate, that is, the amount of sulfuric acid added is controlled.
  • the amount of sulfuric acid added may not completely convert excess calcium into calcium sulfate, and then the phosphoric acid is added to react with the excess calcium to form calcium dihydrogen phosphate to avoid excessive calcium in the product.
  • a quality qualified calcium dihydrogen phosphate product is provided.
  • reaction of calcium chloride and phosphoric acid to form calcium dihydrogen phosphate and hydrochloric acid is a strong acid to form a strong acid, it is a reversible reaction, and if the ratio of phosphoric acid to calcium ion is completely completely reacted according to theoretical calculation, the reaction may be incomplete. , causing the calcium dihydrogen phosphate product to fail.
  • step A if adding phosphoric acid, it is necessary to add excess phosphoric acid to completely convert the remaining excess calcium into calcium dihydrogen phosphate, after dechlorination, defluorination and dehydration by heating,
  • the phosphoric acid neutralizing agent converts the remaining phosphoric acid to calcium dihydrogen phosphate. Or the amount of sulfuric acid added is higher than the theoretical calculation, so that the remaining calcium in the filtrate is relatively less and the phosphoric acid is relatively more.
  • the phosphoric acid neutralizing agent is at least one of lime, calcium carbonate, and calcium phosphate.
  • the heat preservation separation can prevent product precipitation, increase the yield of calcium dihydrogen phosphate and the purity of calcium sulfate, and reduce the energy consumption of the subsequent steps.
  • step A of the above method when sulfuric acid is added to react with calcium ions to form calcium sulfate, a small amount of intermediate may be generated. If the temperature is slightly lower, the intermediate will be resolved, which may result in a decrease in the yield of calcium dihydrogen phosphate. Therefore, this step can also be carried out at a temperature of 60 to 100 ° C. If the step is not kept warm, only the yield of calcium dihydrogen phosphate is lowered, and there is no effect on the quality of calcium dihydrogen phosphate.
  • the heating dechlorination, defluorination, and dehydration methods are not particularly limited as long as the water, hydrogen chloride, and hydrogen fluoride in the system can be removed, and the reaction can be carried out to the right, and vacuum concentration and fogging are employed.
  • Conventional methods such as crystallization, disc, and cylinder can be used, and the heating temperature and time are determined according to different heating methods and without decomposing the calcium phosphate salt.
  • step A of the method of the invention in the dechlorination, defluorination and dehydration, the above reaction is promoted to the right due to the reduction of hydrogen chloride, which is equivalent to one step of heating, simultaneously achieving dechlorination, defluorination, dehydration and promoting product formation.
  • the purpose is different from the conventional chemical method of adding fluorine to remove defluorination agent, which not only has simple operation and saves steps, but also saves the use of a large number of defluorination agents, saves raw materials, and obtains calcium dihydrogen phosphate product with excellent performance.
  • the liquid 1 in the step B of the method of the present invention contains ions such as Ca 2+ , H 2 PO 4 - , Cl - , F - , and magnesium iron aluminum.
  • ions such as Ca 2+ , H 2 PO 4 - , Cl - , F - , and magnesium iron aluminum.
  • Such as F - magnesium iron aluminum plasma, first add alkaline calcium salt to control the pH to 1.2 ⁇ 2.2 to obtain a composite precipitation of calcium fluoride and iron aluminum, thereby filtering to remove fluorine and some iron and aluminum impurities; then add alkaline calcium salt Control the pH to 4.8 ⁇ 6.2 to precipitate the phosphate to obtain the product calcium hydrogen phosphate; then add the alkaline calcium salt to control the magnesium in the pH of 9 ⁇ 11 precipitation system; finally in order to recover the calcium chloride in the system, concentrate and then add
  • the sulfuric acid reaction obtains gypsum with high purity, so that the purpose of removing impurities and recovering useful ionized calcium and phosphate is achieved in this step, and the obtained product calcium hydrogen phosphate and gypsum have high purity and excellent quality.
  • the hydrogen chloride produced in the steps A and B of the method of the invention can be recovered for decomposing the phosphate rock, thereby realizing the recycling of hydrogen chloride and saving the cost.
  • step A of the process of the invention The main reaction equations involved in step A of the process of the invention are as follows:
  • step B of the process of the invention The main reaction equations involved in step B of the process of the invention are as follows:
  • Step A adding hydrochloric acid to decompose the filter cake 1, calculating the amount of hydrochloric acid added according to CaO in the filter cake 1, and reacting for 30 minutes, then thickly separating, the slurry is returned to the acid leaching portion and reacted with the thick slurry, and the filtrate 2 contains calcium ions.
  • Phosphate ion according to P 2 O 5 /CaO which forms calcium dihydrogen phosphate, additionally added with sulfuric acid to obtain calcium sulfate, which is washed to obtain high quality gypsum.
  • the remaining liquid is defluorinated, dechlorinated and dehydrated by atomization to obtain qualified calcium dihydrogen phosphate. product.
  • Step B the filtrate 1 is added with an alkaline calcium salt to control the pH to 1.2 to 2.2 for defluorination and impurity removal, and then the alkaline calcium salt is added to adjust the pH value to 4.8 to 6.2 to obtain a calcium phosphate product, but the alkaline calcium is obtained.
  • the salt is adjusted to pH 9-11 to remove MgO.
  • 98% sulfuric acid is added to form calcium sulfate crystals, which are filtered and washed to obtain high-purity gypsum. Synchronously formed dilute hydrochloric acid is recycled to the dilute acid hydrolysis step to decompose the phosphate rock.
  • Table 2-7 The results obtained are shown in Table 2-7 below.

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Abstract

一种利用盐酸与磷矿生产磷酸钙盐及高纯石膏的方法，包括以下步骤：用盐酸不完全分解磷矿，固液分离得固体1和液体1；A、处理固体1：固体1与盐酸反应，过滤分离得到滤渣和滤液2；滤液2中加入硫酸，过滤后的滤液3经加热脱氯、脱氟、脱水，即得磷酸二氢钙；B、处理液体1：①除去液体1中的氟；②加钙制得磷酸氢钙；③除镁；④加硫酸制得高纯石膏。该方法步骤简便，成本低廉，制备得到的磷酸钙盐满足标准，且所得石膏质量好。

Description

利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法 技术领域
本发明属于饲料及肥料技术领域，具体涉及一种利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法。
背景技术
磷酸钙盐可用作肥料级磷酸钙盐，广泛适用于农业生产中，主要用作配置复混肥的原料，也可直接施用于农田；磷酸钙盐可用作饲料级磷酸钙盐，适用于畜禽、水产等动物，是一种用于补充畜禽、水产动物钙磷营养的饲料添加剂。
行业内普遍认为P 2O 5在24％-28％为中品位磷矿，18％-24％为低品位磷矿。中国磷矿资源比较丰富，已探明资源总量仅次于摩洛哥，位居世界第二位。中国磷矿资源总体上具有以下几个主要特征：储量较大，分布集中；中低品位矿多，富矿少，中国磷矿品位较差，P 2O 5平均含量在17％左右，富矿仅占磷矿石总量的约85％，因此中国大部分的磷矿必须经过选矿富矿后才能满足磷酸和高浓度磷复合肥生产的需求；难选矿多，易选矿少，在中国磷矿储量中，沉积型磷块盐(胶磷矿)多，占全国总储量的85％，其中大部分为中低品位矿石，同时中国磷矿90％是高镁磷矿，其矿石中有用矿物的粒度细，和脉石结合紧密，不易分离，中国磷矿石世界上难选的磷矿石之一。
目前生产饲料级或肥料磷酸钙盐的方法多为先使用硫酸与磷精矿反应生成湿法磷酸，湿法磷酸经过预处理、脱氟净化，再与碳酸钙等钙源反应生成磷酸钙盐料浆，经高温雾化烘干得到合格产品。该工艺流程复杂，成本高，对磷矿原料的适应性差。专利CN105921259A公开了一种利用中低品位混合磷矿石生成饲料级磷酸二氢钙的方法，看似采用中低品位磷矿作为原料，然而实际上还是将该中低品位钙镁质磷矿石矿浆中依次加入抑制剂和捕收剂，反浮选，制得磷精矿再进一步与硫酸反应。同时现有生产磷酸钙盐的工艺大多先将磷矿中的钙转化成磷石膏(杂质很高的硫酸钙)作为工业废弃物而排除掉，磷石膏的堆存和消化是本行业的难点，已经影响到本行业的可持续发展，而在后续生产磷酸钙盐的过程中又需要加入大量的碳酸钙等作为钙源，从而造成了资源的极大浪费。
发明内容
本发明所要解决的技术问题是提供一种利用盐酸和磷矿生产磷酸钙盐及高纯石膏 的方法。该方法包括以下步骤：
用质量浓度15％以下的盐酸不完全分解磷矿，固液分离得到固体1和液体1；其中，固体1中质量比P 2O 5/MgO＞6；
A、处理固体1：固体1与盐酸反应，过滤分离得到滤渣和滤液2；滤液2中加入硫酸进行反应，过滤得到滤饼3和滤液3；滤饼3干燥后即为石膏；滤液3加热脱氯、脱氟、脱水，即得磷酸二氢钙；
B、处理液体1：
①液体1中加入碱性钙盐调节pH至1.2～2.2，过滤分离得到滤饼4和滤液4；
②滤液4中加入碱性钙盐调节pH至4.8～6.2，过滤分离得到滤饼5和滤液5，滤饼5即为磷酸氢钙；
③滤液5中加入碱性钙盐调节pH至9～11，过滤分离得到滤饼6和滤液6；
④滤液6与硫酸反应，得到高纯石膏和氯化氢或盐酸。
具体的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤A中，控制硫酸的加入量为使过量的钙完全转化为硫酸钙；所述过量的钙是指滤液2中磷酸与钙转化为磷酸二氢钙后剩余的钙。
优选的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤A中，加入硫酸进行反应同时保温，保温温度为60～100℃。
优选的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤A中，所述固体1与盐酸按摩尔比计CaO︰HCl＝1︰0.8～3。进一步的，所述固体1与盐酸按摩尔比计CaO︰HCl＝1︰1.6～2.4。
优选的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤A中，所述盐酸的质量浓度在5％以上。进一步的，所述盐酸的质量浓度为20～30％。
具体的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤A中，所述固体1与盐酸反应温度为常温～80℃。
优选的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤A中，所述加热脱氯、脱氟、脱水采用负压浓缩、烘箱干燥、雾化、圆盘或圆筒中任意一种实现。
具体的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤B中①，所述碱性钙盐为石灰或碳酸钙中的至少一种。
具体的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤B中②，所述碱性钙盐为石灰或碳酸钙中的至少一种。
具体的，上述利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法步骤B中③，所述碱性钙盐为生石灰或熟石灰中的至少一种。
本发明方法具有以下有益效果：
1、由于稀盐酸不完全分解磷矿具有脱除镁杂质的作用，在工艺步骤B中还有脱除铁、铝、镁等杂质的单元，所以本发明方法不但适用于高品位磷矿和磷精矿，特别适用于高杂质的中低品位磷矿，省去了对原料磷矿精选处理的工序投资；由于中低品位磷矿储量大价格低，因此本工艺具有显著的成本优势。
2、本发明方法由工艺步骤A中制得磷酸二氢钙，工艺步骤B中制得磷酸氢钙产品，将两种产品复配加工即可以得到磷酸一二钙产品，所以，本工艺的实施可以一次性得到三种磷酸钙盐产品。
3、本发明方法中磷矿的钙全部转化为离子态的钙，步骤A中的磷酸与离子态的钙能充分反应，不产生包裹，磷酸二氢钙产品纯度高，游离酸含量低，后续产品不易结块，质量优异，满足GBT22548-2008对饲料级磷酸二氢钙要求。
4、本发明方法的实施可以得到两种化学石膏，其中步骤B制得含磷、氟特别低的高纯石膏，可以进一步加工成高强度的α石膏或晶须石膏产品，步聚A制得的石膏可以生产加工β建筑石膏，并可以由α、β两种石膏混合配制出陶模石膏，满足不同客户市场的需求。
5、本发明方法制备得到的磷酸钙盐中的部分(或全部)磷来源于磷矿中的磷，此部分P 2O 5没有通过硫酸制取磷酸获得，从而不产生难以处理的磷石膏，减少了工业废弃物的排放，实施本工艺具有极高的社会效益和经济效益。
6、本发明方法步骤A通过加热一个工序过程完成了脱氯、脱氟、脱水以及促进产品生产四个目的，提升了生产效率，实现了磷酸钙盐的高效生产；同时步骤A无需外加脱氟剂进行化学脱氟，优化了流程，节约了成本。
7、本发明方法产生的盐酸能够封闭循环回收利用，减少尾气排放，不会造成环境污染，同时减少了对其它生产要素的消耗，具有极高的经济效益和环保效益。
附图说明
图1本发明方法的工艺流程示意图
具体实施方式
一种利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，包括以下步骤：
用质量浓度15％以下的盐酸不完全分解磷矿，固液分离得到固体1和液体1；其中， 按质量比计，固体1中P 2O 5/MgO＞6；本步骤目的是除去磷矿中绝大部分镁，镁进入液体1，相当于对磷矿进一步提纯，从而得到的固体1所含杂质较少，有利于滤饼进行步骤A的反应而得到质量优异的磷酸二氢钙；液体1中含有Ca 2+、H 2PO 4 -、Cl -、F -、镁铁铝等离子；
A、处理固体1：固体1与盐酸反应，过滤分离得到滤渣和滤液2；滤液2中加入硫酸进行反应，过滤得到滤饼3和滤液3；滤饼3干燥后即为石膏；滤液3加热脱除体系中的氯化氢、氟化氢和水，并同时产生了磷酸二氢钙，从而一步制得合格的磷酸二氢钙；
B、处理液体1：
①液体1中加入碱性钙盐提供钙源，调节体系pH至1.2～2.2使体系中的氟与钙反应生成CaF 2，以达到脱氟的目的，过滤分离得滤饼4脱氟渣和滤液4；
②滤液4中加入碱性钙盐提供钙源，调节体系pH至4.8～6.2使体系中的磷酸根与钙反应得到磷酸氢钙沉淀，过滤分离得到滤饼5和滤液5，滤饼5即为磷酸氢钙，干燥、收集滤饼5即可；
③滤液5中加入碱性钙盐调节pH至9～11，使体系中的杂质镁离子沉淀为氢氧化镁，同时也达到除去体系中的少量铁、铝离子的目的，过滤分离得滤饼6脱镁渣和滤液6氯化钙溶液；
④滤液6氯化钙溶液浓缩为氯化钙浆料，然后与硫酸反应，得到高纯石膏和氯化氢或盐酸。
本发明方法中，所采用的原料磷矿为高杂质磷矿、磷精矿、高中低品位磷矿均可，有效成分均为Ca 5F(PO 4) 3。行业内普遍认为P 2O 5在24～28％为中品位磷矿，18～24％为低品位磷矿，高于28％为高品位磷矿。
本发明方法中，盐酸不完全分解磷矿中所述的不完全分解是指：盐酸分解磷矿时，磷矿中的磷没有完全转化为酸溶性的磷。影响盐酸分解磷矿程度的因素包括磷矿的活性、磷矿的粒度、反应温度、反应时间、盐酸与磷矿的配比等，控制不完全分解可从上述几个因素进行调节，本领域技术人员可根据磷矿类型、生产实际需求和生产所具有的条件等，灵活地从上述任何一个或几个因素调节、选择、控制磷矿分解的原料粒度、反应温度时间、原料配比等参数，以控制磷矿不完全分解，且还需同时满足固体1中P 2O 5/MgO质量比＞6即可。设计本步骤的意义在于脱除磷矿中的镁，提高磷矿纯度，有利于提高最终的产品质量。控制盐酸的质量浓度为15％以下是为了控制不完全酸解反应中固相和液相中磷的分配比例；控制P 2O 5/MgO质量比＞6是为了保证步骤A所得的 磷酸二氢钙产品质量合格。
本发明方法中，所述的固液分离即为：对盐酸不完全分解磷矿后的体系进行分离，将固体和液体分开，可采用本领域常规的分离方式，如过滤、稠厚、静置、离心等方式。当采用过滤的方式时，滤饼即为本发明的固体1，滤液即为本发明的液体1；当采用稠厚的方式时，可采用稠厚器进行稠厚，经稠厚器分离得到稠浆和清液，稠浆即为本发明的固体1，清液即为本发明的液体1；当采用静置的方式时，下层的浆料即为本发明的固体1，上层的上清液即为本发明的液体1。本发明固液分离也可采用过滤、稠厚、静置、离心等结合的方式，如静置后过滤、稠厚后过滤等等方式，只要能够达到分离液体和固体或浆料即可。
本发明方法步骤A中，对盐酸用量无特别限定，但是如盐酸用量过高，会增大设备负荷，也不利于后期盐酸回收，同时浪费原料；如盐酸用量过低，会造成分解磷矿不完全，分解率低，造成磷矿浪费。所以，优选的，按摩尔比计，固体1中的钙按CaO计，控制固体1与盐酸CaO︰HCl＝1︰0.8～3。进一步优选的，CaO︰HCl＝1︰1.6～2.4。
本发明方法步骤A中，盐酸分解固体1中的磷矿很容易进行，在常温下，盐酸质量浓度为20～30％，一般几分钟就能够完全分解磷矿。所以，步骤A盐酸分解磷矿对盐酸的浓度、反应温度、反应时间都没有特别限定。低盐酸浓度也能分解磷矿，但需延长反应时间和/或升高反应温度，且盐酸用量增大，不利于后期加热脱氯、脱氟、脱水，增大设备负荷，增加能耗；同样，反应温度越低，则需使用高浓度盐酸和/或延长反应时间；但盐酸浓度、反应温度、反应时间仅影响反应效率，对所得产品本身的品质没有影响。从效率、经济等方面考虑，优选盐酸的质量浓度在5％以上。进一步的，盐酸的质量浓度为20～30％。优选反应温度常温即可，也可根据实际生产需要对反应温度进行一定调整，如控制反应温度为室温～80℃。
本发明方法步骤A中，加入硫酸的目的是沉淀滤液2中过量的钙，所述过量的钙是指滤液2中磷酸与钙转化为磷酸二氢钙后剩余的钙。实际上，步骤A中额外加入硫酸时，本身存在滤液2中的磷酸与钙并未生成磷酸二氢钙，此处只是通过理论计算将该部分钙刨除，剩余的钙即为需要外加硫酸与其进行反应生成硫酸钙。
例如，从理论计算量来看，假设经测定，步骤A所得滤液2中含有3mol磷酸和5mol氯化钙，加热脱氟、脱氯、脱水所得产品为磷酸二氢钙，3mol磷酸需要消耗1.5mol钙，则还剩余3.5mol钙，此处的3.5mol钙则为过量的钙，则需要加入3.5mol硫酸与过量的3.5mol钙反应，从而所得产物为磷酸二氢钙。需要说明的是：上述数据均是理论计算量， 在实际的操作和反应过程中，可能会存在一定偏差，实际上只要保证制备得到的产品磷酸钙盐质量合格即可。
此外，可根据实际工厂对硫酸钙的需要来控制生产的硫酸钙的量，即控制硫酸的加入量。当对硫酸钙需要较低时，加入的硫酸量也可不完全使过量的钙转化为硫酸钙，然后加入磷酸与剩余的过量的钙反应生成磷酸二氢钙，避免产品中钙过高，从而制得质量合格的磷酸二氢钙产品。
进一步的，由于氯化钙与磷酸反应生成磷酸二氢钙和盐酸的反应为中强酸制强酸的反应，为可逆反应，若磷酸与钙离子比例仅仅根据理论计算刚好完全反应，可能导致反应不彻底，造成磷酸二氢钙产品不合格。所以，实际生产中为了保证产品合格，步骤A中，如加入磷酸，则需加入过量的磷酸使剩余的过量的钙完全转化为磷酸二氢钙，经加热脱氯、脱氟、脱水后，加入磷酸中和剂使剩余的磷酸转化为磷酸二氢钙。或者加入硫酸的量比理论计算量高一些，则使滤液中剩余的钙相对少一些、磷酸相对多一些。所述磷酸中和剂为石灰、碳酸钙、磷酸钙中的至少一种。
上述方法步骤A中，保温分离可防止产品析出，提高磷酸二氢钙的收率和硫酸钙的纯度，同时减少后续步骤能耗。
上述方法步骤A中，加入硫酸与钙离子反应生成硫酸钙时，可能会有少量的中间体产生，如温度稍低，中间体会解析出，从而会导致磷酸二氢钙的产率有所降低。所以，该步骤还可以进行保温，温度为60～100℃。如该步骤不保温，只是降低了磷酸二氢钙的产率，而对磷酸二氢钙的质量没有影响。
上述方法步骤A中，所述的加热脱氯、脱氟、脱水方式无特别限定，只要能够使体系中的水、氯化氢、氟化氢除去，从而使反应向右进行即可，采用负压浓缩、雾化、圆盘、圆筒等常规方式均可，至于加热温度和时间根据不同的加热方式和不使磷酸钙盐分解而定。本发明方法步骤A在脱氯、脱氟、脱水时，由于氯化氢的减少，促进了上述反应向右进行，相当于一个加热步骤一步同时达到了脱氯、脱氟、脱水以及促进产品生成四个目的，有别于常规加入脱氟剂除去氟的化学方式，不仅操作简单、节约步骤，而且省去了大量脱氟剂的使用，节约原料，且获得了性能优异的磷酸二氢钙产品。
本发明方法步骤B的液体1中，含有Ca 2+、H 2PO 4 -、Cl -、F -、镁铁铝等离子，为了能够得到质量优异的磷酸氢钙产品，需要除去滤液中的杂质离子如F -、镁铁铝等离子，首先外加碱性钙盐控制pH至1.2～2.2得到氟化钙和铁铝的复合沉淀，从而过滤脱除氟和部分铁铝杂质；接着再外加碱性钙盐控制pH为4.8～6.2将磷酸根沉淀出来，得到产 品磷酸氢钙；然后再外加碱性钙盐控制pH为9～11沉淀体系中的镁；最终为了回收体系中的氯化钙，浓缩后加入硫酸反应即得纯度较高的石膏，从而本步骤达到了除去杂质，回收有用离子钙、磷酸根的目的，且所得产品磷酸氢钙和石膏纯度高，品质优异。
本发明方法步骤A、B产生的氯化氢能够回收用于分解磷矿，从而实现了氯化氢的循环使用，节约了成本。
本发明方法步骤A中涉及的主要的反应方程式如下：
磷矿分解：Ca 5F(PO 4) 3+10HCl→3H 3PO 4(酸解)+5CaCl 2+HF↑
加热脱氯、脱氟、脱水产品为磷酸二氢钙时的化学方程式：
5CaCl 2+3H 3PO 4(酸解)+3.5H 2SO 4(外加)→1.5Ca(H 2PO 4) 2+3.5CaSO 4(过滤)↓+10HCl
本发明方法步骤B中涉及的主要的反应方程式如下：
脱氟：Ca 2++F -→CaF 2↓
DCP生成：Ca 2++PO 4 3-→CaHPO 4
除镁：Mg 2++OH -→Mg(OH) 2↓
实施例1-4
按下表1选择磷矿，下表2控制各步骤原料比例关系。用盐酸分解磷矿30min，过滤分离得滤饼1(即固体1)和滤液1(即液体1)；
步骤A：加入盐酸分解滤饼1，根据滤饼1中的CaO计算加入盐酸的量，反应30min后稠厚分离，浆料返回酸浸部分与稠浆一起再反应，滤液2中含有钙离子、磷酸根离子，根据生成磷酸二氢钙的P 2O 5/CaO额外加入硫酸沉淀得到硫酸钙，洗涤得到优质石膏，剩余液体经雾化脱氟、脱氯、脱水，得到合格的磷酸二氢钙产品。
步骤B、滤液1加入碱性钙盐控制pH为1.2～2.2进行脱氟除杂，然后再加入碱性钙盐调节pH值为4.8～6.2中和制得磷酸钙盐产品，然而经碱性钙盐调节pH至9～11脱除MgO，经浓缩后加入98％硫酸生成硫酸钙结晶，过滤洗涤得到高纯石膏，同步生成的稀盐酸回用至稀酸酸解工序分解磷矿。所得结果见下表2-7。
表1磷矿指标
P 2O 5％ CaO％ MgO％ Fe 2O 3％ Al 2O 3％ SiO 2％ F％ SO 4 2-％ H 2O％
28.32 40.98 1.58 1.63 1.43 13.84 2.66 0.54 1.00
表2
Figure PCTCN2017117517-appb-000001
Figure PCTCN2017117517-appb-000002
表3
Figure PCTCN2017117517-appb-000003
表4
Figure PCTCN2017117517-appb-000004
表5
Figure PCTCN2017117517-appb-000005
表6
Figure PCTCN2017117517-appb-000006
表7
Figure PCTCN2017117517-appb-000007
Figure PCTCN2017117517-appb-000008
综上可以看出，本发明方法所生产的磷酸氢钙、磷酸二氢钙、石膏均优于国家标准。

Claims (9)

  1. 利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：包括以下步骤：
    用质量浓度15％以下的盐酸不完全分解磷矿，固液分离得到固体1和液体1；其中，固体1中质量比P 2O 5/MgO＞6；
    A、处理固体1：固体1与盐酸反应，过滤分离得到滤渣和滤液2；滤液2中加入硫酸进行反应，过滤得到滤饼3和滤液3；滤饼3干燥后即为石膏；滤液3加热脱氯、脱氟、脱水，即得磷酸二氢钙；
    B、处理液体1：
    ①液体1中加入碱性钙盐调节pH至1.2～2.2，过滤分离得到滤饼4和滤液4；
    ②滤液4中加入碱性钙盐调节pH至4.8～6.2，过滤分离得到滤饼5和滤液5，滤饼5即为磷酸氢钙；
    ③滤液5中加入碱性钙盐调节pH至9～11，过滤分离得到滤饼6和滤液6；
    ④滤液6与硫酸反应，得到高纯石膏和氯化氢或盐酸。
  2. 根据权利要求1所述的利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：步骤A中，控制硫酸的加入量为使过量的钙完全转化为硫酸钙；所述过量的钙是指滤液2中磷酸与钙转化为磷酸二氢钙后剩余的钙。
  3. 根据权利要求1所述的利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：步骤A中，加入硫酸进行反应同时保温，保温温度为60～100℃。
  4. 根据权利要求1所述的利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：步骤A中，所述固体1与盐酸按摩尔比计CaO︰HCl＝1︰0.8～3；进一步的，所述固体1与盐酸按摩尔比计CaO︰HCl＝1︰1.6～2.4。
  5. 根据权利要求1或4所述的利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：步骤A中，所述盐酸的质量浓度在5％以上；进一步的，所述盐酸的质量浓度为20～30％。
  6. 根据权利要求1～5任一项所述的利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：步骤A中，所述加热脱氯、脱氟、脱水采用负压浓缩、烘箱干燥、雾化、圆盘或圆筒中任意一种实现。
  7. 根据权利要求1～6任一项所述的利用盐酸和磷矿生产磷酸钙盐及高纯石 膏的方法，其特征在于：步骤B中①，所述碱性钙盐为石灰或碳酸钙中的至少一种。
  8. 根据权利要求1～6任一项所述的利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：步骤B中②，所述碱性钙盐为石灰或碳酸钙中的至少一种。
  9. 根据权利要求1～6任一项所述的利用盐酸和磷矿生产磷酸钙盐及高纯石膏的方法，其特征在于：步骤B中③，所述碱性钙盐为生石灰或熟石灰中的至少一种。
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