CN109836177B - Method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphorite - Google Patents
Method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphorite Download PDFInfo
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- 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
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- 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
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- 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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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/26—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke
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- C05—FERTILISERS; MANUFACTURE THEREOF
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- C05B3/00—Fertilisers based essentially on di-calcium phosphate
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- C05B7/00—Fertilisers based essentially on alkali or ammonium orthophosphates
Abstract
The invention belongs to the technical field of feed, and particularly relates to a method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite. The invention aims to solve the technical problem of providing a method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite, which comprises the following steps: incompletely decomposing phosphorite with hydrochloric acid, and performing solid-liquid separation to obtain solid 1 and liquid 1; A. treatment of solid 1: reacting the solid 1 with hydrochloric acid, and filtering and separating to obtain filter residue and filtrate 2; mixing the filtrate 2 with phosphoric acid to obtain fine slurry, heating the fine slurry for dechlorination, defluorination and dehydration to obtain calcium phosphate salt; B. treatment liquid 1: removing fluorine in the liquid 1; ② calcium is added to prepare calcium hydrophosphate; removing magnesium; fourthly, sulfuric acid is added to prepare the high-purity gypsum. The method has simple steps and low cost, the prepared calcium phosphate completely meets the national standard, and the obtained gypsum has excellent quality.
Description
Technical Field
The invention belongs to the technical field of feed and fertilizer, and particularly relates to a method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite.
Background
The calcium phosphate can be used as fertilizer-grade calcium phosphate, is widely applicable to agricultural production, is mainly used as a raw material for preparing compound fertilizers, and can also be directly applied to farmlands; the calcium phosphate salt can be used as feed-grade calcium phosphate salt, is suitable for animals such as livestock, poultry and aquatic products, and is a feed additive for supplementing calcium and phosphorus nutrition for livestock, poultry and aquatic animals.
General opinion P in the industry2O524 to 28 percent of the phosphate ore is medium-grade phosphate ore, and 18 to 24 percent of the phosphate ore is low-grade phosphate ore. China phosphorite resources are rich, and the total amount of the resources is proved to be second to that of Morocco and is the second place in the world. The Chinese phosphorite resource has the following main characteristics on the whole: the reserves are large and the distribution is centralized; more middle and low grade ore, less rich ore, poorer quality of Chinese phosphorite, P2O5The average content is about 17 percent, and the rich ore only accounts for about 85 percent of the total amount of the phosphate ore, so most of the phosphate ore in China can meet the production requirements of phosphoric acid and high-concentration phosphorus compound fertilizer after ore dressing and enrichment; the mineral separation is difficult, the mineral separation is easy, in the reserves of the Chinese phosphorite, the deposited phosphorite (collophanite) is more and accounts for 85 percent of the total reserves in China, most of the deposited phosphorite (collophanite) is middle-low grade ore, and 90 percent of the Chinese phosphorite is high-magnesium phosphorite, the useful minerals in the ore have fine granularity, are tightly combined with gangue and are not easy to separate, and the Chinese phosphorite is one of the difficult-to-separate phosphorites in the world.
At present, most of the methods for producing feed-grade or fertilizer calcium phosphate salt are to use sulfuric acid to react with phosphate concentrate to generate wet-process phosphoric acid, the wet-process phosphoric acid is pretreated, defluorinated and purified, then reacts with calcium sources such as calcium carbonate and the like to generate calcium phosphate slurry, and the calcium phosphate slurry is atomized and dried at high temperature to obtain qualified products. The process flow is complex, the cost is high, and the adaptability to the phosphorite raw material is poor. Patent CN105921259A discloses a method for producing feed grade monocalcium phosphate from middle-low grade mixed phosphate ore, which seems to adopt middle-low grade phosphate ore as raw material, however, actually, inhibitor and collector are added into the ore pulp of middle-low grade calcium magnesium phosphate ore in sequence, and reverse flotation is carried out to prepare phosphate concentrate, which is further reacted with sulfuric acid. Meanwhile, most of the existing processes for producing calcium phosphate salt convert calcium in phosphate rock into phosphogypsum (calcium sulfate with high impurity) to be removed as industrial waste, the stacking and digestion of the phosphogypsum are difficult points of the industry, the sustainable development of the industry is influenced, and a large amount of calcium carbonate and the like are required to be added as a calcium source in the subsequent process for producing the calcium phosphate salt, so that the resource is greatly wasted.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite. The method comprises the following steps:
incompletely decomposing phosphorite with hydrochloric acid with mass concentration of below 15%, and performing solid-liquid separation to obtain solid 1 and liquid 1; wherein the mass ratio P in the solid 12O5/MgO＞6；
A. Treatment of solid 1: reacting the solid 1 with hydrochloric acid, and filtering and separating to obtain filter residue and filtrate 2; mixing the filtrate 2 with phosphoric acid to obtain fine slurry, heating the fine slurry for dechlorination, defluorination and dehydration to obtain calcium phosphate salt;
B. treatment liquid 1:
adding alkaline calcium salt into the liquid 1 to adjust the pH value to 1.2-2.2, and filtering and separating to obtain a filter cake 3 and a filtrate 3;
secondly, adding alkaline calcium salt into the filtrate 3 to adjust the pH value to 4.8-6.2, and filtering and separating to obtain a filter cake 4 and a filtrate 4, wherein the filter cake 4 is calcium hydrophosphate;
thirdly, adding alkaline calcium salt into the filtrate 4 to adjust the pH value to 9-11, and filtering and separating to obtain a filter cake 5 and a filtrate 5;
fourthly, the filtrate 5 reacts with sulfuric acid to obtain high-purity gypsum and hydrogen chloride or hydrochloric acid.
In the step A of the method for producing the calcium phosphate salt and the high-purity gypsum by using the hydrochloric acid and the phosphorite, the filtrate 2 is mixed with the phosphoric acid after being concentrated.
In the step A of the method for producing the calcium phosphate salt and the high-purity gypsum by using the hydrochloric acid and the phosphorite, the excessive calcium is completely converted into the calcium phosphate salt by the adding amount of the phosphoric acid; the excess calcium refers to the calcium remaining after the phosphoric acid and calcium in the filtrate 2 are converted into calcium phosphate salts.
Further, in the step a of the method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphate rock, when the calcium phosphate salt is monocalcium phosphate, excessive phosphoric acid is added to completely convert the excessive calcium into monocalcium phosphate, and after fine slurry heating dechlorination, defluorination and dehydration, a phosphoric acid neutralizing agent is added to convert the residual phosphoric acid into monocalcium phosphate. The phosphoric acid neutralizer is at least one of lime and calcium carbonate.
Preferably, in the step a of the method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphorite, the solid 1 and hydrochloric acid are CaO: HCl: 1: 0.8-3 in a molar ratio. Further, the solid 1 and hydrochloric acid are in a molar ratio of CaO: HCl to 1: 1.6-2.4.
Preferably, in the step a of the method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite, the mass concentration of the hydrochloric acid is more than 5%. Further, the mass concentration of the hydrochloric acid is 20-30%.
Specifically, in the step A of the method for producing the calcium phosphate salt and the high-purity gypsum by using the hydrochloric acid and the phosphorite, the reaction temperature of the solid 1 and the hydrochloric acid is between normal temperature and 80 ℃.
Specifically, in the step A of the method for producing the calcium phosphate salt and the high-purity gypsum by using the hydrochloric acid and the phosphorite, the mixing temperature of the filtrate 2 and the phosphoric acid is between normal temperature and 80 ℃.
Preferably, in the step a of the method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite, the heating dechlorination, defluorination and dehydration are realized by any one of negative pressure concentration, oven drying, atomization and disc or cylinder.
Specifically, in the step B of the method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite, the basic calcium salt is at least one of lime or calcium carbonate.
Specifically, in the step B of the method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphorite, the alkaline calcium salt is at least one of lime or calcium carbonate.
In step B, the alkaline calcium salt is at least one of lime or hydrated lime (or called lime milk and the like).
The method of the invention has the following beneficial effects:
1. as the dilute hydrochloric acid incompletely decomposes the phosphorite and has the function of removing magnesium impurities, and a unit for removing iron, aluminum, magnesium and other impurities is arranged in the process step B, the method is not only suitable for high-grade phosphorite and phosphate concentrate, but also particularly suitable for medium and low-grade phosphorite with high impurities, and saves the process investment of fine selection treatment of the raw material phosphorite; the process has obvious cost advantage due to large storage capacity and low price of the medium and low grade phosphorite.
2. In the method, calcium dihydrogen phosphate can be prepared in the process step A, calcium hydrogen phosphate can be prepared in the process step B, and the monocalcium phosphate product can be obtained by compounding and processing the two products, so that three calcium phosphate products can be obtained at one time by implementing the process.
3. In the method, the calcium of the phosphorite is completely converted into the ionic calcium, the phosphoric acid in the step A and the ionic calcium can fully react without generating package, the calcium phosphate salt product has high purity and low free acid content, the subsequent product is not easy to agglomerate, the quality is excellent, and the requirement of GBT22548-2008 on feed-grade monocalcium phosphate is met.
4. Part of phosphorus in the calcium phosphate salt prepared by the method is derived from phosphorus in phosphorite, and the part P2O5The method is not obtained by preparing phosphoric acid by using sulfuric acid, so that ardealite which is difficult to treat is not generated, the emission of industrial waste is reduced, and the method has extremely high social benefit and economic benefit.
5. The method has the advantages that step A of the method finishes four purposes of dechlorination, defluorination, dehydration and product production promotion through a heating process, improves the production efficiency and realizes the high-efficiency production of calcium phosphate; meanwhile, in the step A, no defluorinating agent is added for chemical defluorination, so that the process is optimized, and the cost is saved.
6. The hydrochloric acid generated by the method can be recycled in a closed cycle manner, the tail gas emission is reduced, the environmental pollution is avoided, the consumption of other production factors is reduced, and the method has extremely high economic benefit and environmental protection benefit.
7. The high-purity gypsum with particularly low phosphorus and fluorine content prepared by the step B of the method can be further processed into high-strength alpha gypsum or whisker gypsum products.
Drawings
FIG. 1 is a schematic process flow diagram of the process of the present invention
Detailed Description
A method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite comprises the following steps:
incompletely decomposing phosphorite with hydrochloric acid with mass concentration below 15%, and separating solid to obtain solid 1 and liquid 1; wherein, the solid 1 contains P in mass ratio2O5MgO > 6; the purpose of the step is to remove most of magnesium in the phosphorite, the magnesium enters the liquid 1, which is equivalent to the purification of the phosphorite, so that the obtained solid 1 contains less impurities, and the solid 1 is favorable for the reaction of the step A to obtain calcium phosphate with excellent quality; liquid 1 contains Ca2+、H2PO4 -、Cl-、F-Magnesium iron aluminum plasma;
A. treatment of solid 1: reacting the solid 1 with hydrochloric acid, and filtering and separating to obtain filter residue and filtrate 2; mixing the filtrate 2 with phosphoric acid to obtain fine slurry, wherein the fine slurry mainly contains Ca2+、Cl-、H+The fine slurry is heated to remove hydrogen chloride, hydrogen fluoride and water in the system, and simultaneously calcium phosphate salt is generated, so that qualified calcium phosphate salt is prepared in one step;
B. treatment liquid 1:
adding alkaline calcium salt into the liquid 1 to provide a calcium source, adjusting the pH of the system to 1.2-2.2 to enable fluorine in the system to react with calcium to generate CaF2To achieve the aim of defluorination, filtering and separating to obtain defluorination residues of the filter cake 3 and filtrate 3;
adding alkaline calcium salt into the filtrate 3 to provide a calcium source, adjusting the pH of the system to 4.8-6.2 to enable phosphate radicals in the system to react with calcium to obtain calcium hydrophosphate precipitate, filtering and separating to obtain a filter cake 4 and a filtrate 4, wherein the filter cake 4 is calcium hydrophosphate, drying and collecting the filter cake 4;
thirdly, adding alkaline calcium salt into the filtrate 4 to adjust the pH value to 9-11, precipitating impurity magnesium ions in the system into magnesium hydroxide, removing a small amount of iron and aluminum ions in the system, and filtering and separating to obtain filter cake 5 magnesium removal slag and filtrate 5 calcium chloride solution;
fourthly, concentrating the filtrate 5 calcium chloride solution into calcium chloride slurry, and then adding sulfuric acid for reaction to obtain high-purity gypsum and hydrogen chloride or hydrochloric acid.
In the method, the adopted raw material phosphate ore can be high-impurity phosphate ore, phosphate concentrate and high, medium and low-grade phosphate ore, and the effective components are Ca5F(PO4)3. General opinion P in the industry2O5The medium-grade phosphate ore accounts for 24-28%, the low-grade phosphate ore accounts for 18-24%, and the high-grade phosphate ore accounts for more than 28%.
In the method, the incomplete decomposition of the phosphorite by the hydrochloric acid is as follows: when the hydrochloric acid decomposes the phosphorus ore, the phosphorus in the phosphorus ore is not completely converted into acid-soluble phosphorus. Factors influencing the degree of phosphorite decomposition by hydrochloric acid include the activity of phosphorite, the granularity of phosphorite, the reaction temperature, the reaction time, the proportion of hydrochloric acid and phosphorite and the like, the incomplete decomposition control can be adjusted by the factors, and a person skilled in the art can flexibly adjust, select and control the parameters of the granularity of raw materials decomposed by phosphorite, the reaction temperature time, the raw material proportion and the like from any one or more factors according to the type of phosphorite, the actual production requirement, the production conditions and the like so as to control the incomplete decomposition of phosphorite and simultaneously meet the requirement of P in the solid 12O5The mass ratio of MgO/MgO is more than 6. The significance of the design of the step lies in removing magnesium in the phosphorite, improving the purity of the phosphorite and being beneficial to improving the final product quality. The mass concentration of the hydrochloric acid is controlled to be below 15 percent so as to control the distribution ratio of phosphorus in a solid phase and a liquid phase in the incomplete acidolysis reaction; control P2O5The mass ratio of MgO to MgO is more than 6 so as to ensure that the calcium phosphate product obtained in the step A is qualified in quality.
In the method of the invention, the solid-liquid separation is as follows: separating the system after hydrochloric acid incompletely decomposes phosphorite to separate solid and liquid, and adopting conventional separation modes in the field, such as filtration, thickening, standing, centrifugation and the like. When a filtering mode is adopted, a filter cake is the solid 1 of the invention, and a filtrate is the liquid 1 of the invention; when the thickening mode is adopted, a thickener can be adopted for thickening, thick slurry and clear liquid are obtained through separation by the thickener, the thick slurry is the solid 1, and the clear liquid is the liquid 1; when a standing mode is adopted, the slurry of the lower layer is the solid 1 of the invention, and the supernatant of the upper layer is the liquid 1 of the invention. The solid-liquid separation of the invention can also adopt the combined modes of filtration, thickening, standing, centrifugation and the like, such as filtration after standing, filtration after thickening and the like, as long as the separation of liquid and solid or slurry can be achieved.
In step A of the method, the calcium phosphate salt is calcium hydrogen phosphate, calcium dihydrogen phosphate or monocalcium phosphate.
In the step A of the method, the filtrate 2 is preferably concentrated and then mixed with phosphoric acid, and most of water in the filtrate 2 is removed, so that dechlorination, defluorination and dehydration are not required to remove a large amount of water, the overall energy consumption is greatly saved, and the recovered hydrochloric acid has higher concentration and is more favorable for recycling.
In the step A of the method, the consumption of hydrochloric acid is not particularly limited, but if the consumption of hydrochloric acid is too high, the load of equipment is increased, the recovery of hydrochloric acid in the later period is not facilitated, and raw materials are wasted; if the dosage of hydrochloric acid is too low, the phosphorite can be decomposed incompletely, the decomposition rate is low, and the phosphorite is wasted. Therefore, preferably, the molar ratio of calcium in the solid 1 is calculated according to CaO, and the ratio of CaO to HCl in the solid 1 is controlled to be 1: 0.8-3. Further preferably, CaO: HCl is 1: 1.6-2.4.
In the step A of the method, the hydrochloric acid is easy to decompose the phosphorite in the solid 1, the mass concentration of the hydrochloric acid is 20-30% at normal temperature, and the phosphorite can be completely decomposed within minutes. Therefore, the hydrochloric acid concentration, reaction temperature and reaction time for the hydrochloric acid decomposition of phosphate ore in step A are not particularly limited. The low concentration of hydrochloric acid can decompose phosphorite, but the reaction time needs to be prolonged and/or the reaction temperature needs to be raised, and the consumption of hydrochloric acid is increased, so that the later-stage heating dechlorination, defluorination and dehydration are not facilitated, the equipment load is increased, and the energy consumption is increased; similarly, the lower the reaction temperature, the higher the concentration of hydrochloric acid and/or the longer the reaction time; however, the concentration of hydrochloric acid, the reaction temperature and the reaction time only affect the reaction efficiency, and do not affect the quality of the obtained product. The mass concentration of hydrochloric acid is preferably 5% or more in terms of efficiency, economy, and the like. Furthermore, the mass concentration of the hydrochloric acid is 20-30%. The reaction temperature is preferably normal temperature, or can be adjusted to a certain extent according to actual production needs, for example, the reaction temperature is controlled to be room temperature-80 ℃.
In step A of the method of the present invention, the source and concentration of the added phosphoric acid are not particularly limited, and the concentration may be a conventional concentration. The phosphoric acid produced by the processes of wet-process phosphoric acid, hot-process phosphoric acid and the like can be used.
In step A of the present invention, the amount of phosphoric acid used depends on the particular type of calcium phosphate salt to be produced. Specifically, from the theoretical calculation amount, assuming that the filtrate 2 contains 3mol of phosphoric acid and 5mol of calcium chloride, when the product is calcium hydrogen phosphate, 3mol of phosphoric acid needs to consume 3mol of calcium, and 2mol of calcium still remains, 2mol of phosphoric acid needs to be additionally added to react with the remaining 2mol of calcium, so that the obtained product is completely calcium hydrogen phosphate. When the product is monocalcium phosphate, 1.5mol of calcium needs to be consumed by 3mol of phosphoric acid, 3.5mol of calcium still remains, and 7mol of phosphoric acid needs to be additionally added to react with the remaining 3.5mol of calcium, so that the obtained product is completely monocalcium phosphate. If a mixture of the two is desired, an additional quantity of phosphoric acid of between 2 and 7mol is added. If the added phosphoric acid is less than 2mol, namely the phosphoric acid is insufficient, the calcium in the product is higher, the phosphorus is insufficient, and the national standard cannot be met; if the added phosphoric acid is higher than 7mol, namely the phosphoric acid is excessive, the free acid in the product is too high, the product quality is influenced, and a phosphoric acid neutralizing agent needs to be added for carrying out reverse adjustment. In summary, the phosphoric acid is added in step A in such an amount that the excess calcium is completely converted to calcium phosphate salts; excess calcium refers to the calcium remaining after conversion of the phosphoric acid and calcium in filtrate 2 to calcium phosphate salts.
Furthermore, the reaction of calcium chloride and phosphoric acid to generate calcium phosphate salt and hydrochloric acid is a reaction of preparing strong acid from medium-strength acid, and is a reversible reaction, so when the product is monocalcium phosphate, if the ratio of phosphoric acid to calcium ions is just completely reacted according to theoretical calculation, the reaction may not be complete, and the product of monocalcium phosphate is unqualified. Therefore, in order to ensure the product to be qualified in the actual production, excessive phosphoric acid is added in the step A to ensure that excessive calcium is completely converted into monocalcium phosphate, and after the fine-adjustment slurry is heated for dechlorination, defluorination and dehydration, a corresponding amount of phosphoric acid neutralizer is added to ensure that the residual phosphoric acid is converted into monocalcium phosphate; the phosphoric acid neutralizer is at least one of lime, calcium carbonate and calcium phosphate.
In fact, when phosphoric acid is additionally added in the step A, the phosphoric acid and calcium in the filtrate 2 exist per se and do not generate calcium phosphate salt, and the part of calcium ions is removed by theoretical calculation, and the residual calcium needs to be additionally added with phosphoric acid to react with the phosphoric acid to generate the corresponding calcium phosphate salt.
The data are theoretical calculated quantities, certain deviation may exist in the actual operation and reaction process, and the quality of the prepared calcium phosphate product is qualified.
In this step a, the mixing temperature and the mixing time are not particularly limited. Simply mixing at normal temperature, or adjusting the mixing temperature and mixing time according to the requirement, for example, adjusting the mixing temperature to be between room temperature and 80 ℃.
In step A, the heating dechlorination, defluorination and dehydration methods are not particularly limited as long as the reaction can be performed rightward by removing water, hydrogen chloride and hydrogen fluoride in the system, and any conventional method such as negative pressure concentration, atomization, disk and cylinder can be used, and the heating temperature and time can be determined according to different heating methods and the calcium phosphate salt is not decomposed. In the method, the reaction is promoted to be carried out rightwards due to the reduction of hydrogen chloride during dechlorination, defluorination and dehydration, which is equivalent to a heating step for simultaneously achieving four purposes of dechlorination, defluorination, dehydration and product production promotion in one step.
In the liquid 1 of step B of the process of the present invention, Ca is contained2+、H2PO4 -、Cl-、F-Magnesium, iron, aluminum, etc., and impurities in the filtrate need to be removed to obtain a high quality calcium hydrogen phosphate productIons such as F-Firstly, adding alkaline calcium salt to control the pH value to be 1.2-2.2 to obtain composite precipitate of calcium fluoride and iron and aluminum, and filtering to remove fluorine and part of iron and aluminum impurities; then adding alkaline calcium salt to control the pH value to be 4.8-6.2, and precipitating phosphate radicals to obtain a product calcium hydrophosphate; then adding alkaline calcium salt to control the pH value to be 9-11, and controlling magnesium in a precipitation system; finally, in order to recover calcium chloride in the system, sulfuric acid is added after concentration to react to obtain gypsum with higher purity, so that the purposes of removing impurities and recovering useful ionic calcium and phosphate radicals are achieved in the step, and the obtained products of calcium hydrophosphate and gypsum are high in purity and excellent in quality.
The hydrogen chloride generated in step A, B of the method can be recycled for decomposing the phosphorite, thereby realizing the recycling of the hydrogen chloride and saving the cost.
The main reaction equation involved in step A of the process of the invention is as follows:
decomposing phosphate ore: ca5F(PO4)3+10HCl→3H3PO4(acid hydrolysis) +5CaCl2+HF↑
The chemical equation when the product of heating dechlorination, defluorination and dehydration is calcium monohydrogen phosphate:
5CaCl2+3H3PO4(acid hydrolysis) +2H3PO4(external application) → 5CaHPO4+10HCl
The chemical equation when the product of heating dechlorination, defluorination and dehydration is calcium dihydrogen phosphate:
5CaCl2+3H3PO4(acid hydrolysis) +7H3PO4(external application) → 5Ca (H)2PO4)2+HCl
The chemical equation when the heating dechlorination, defluorination and dehydration products are monocalcium phosphate:
CaCl2+H3PO4(acid hydrolysis) + H3PO4(external application) → CaHPO4+Ca(H2PO4)2+HCl
The main reaction equations involved in step B of the process of the invention are as follows:
defluorination: ca2++F-→CaF2↓
DCP generation: ca2++PO4 3-→CaHPO4
Magnesium removal: mg (magnesium)2++OH-→Mg(OH)2↓
Examples 1 to 4
Phosphate ore was selected according to the following table 1, and the raw material ratio relationship in each step was controlled in the following table 2. Decomposing phosphorite with hydrochloric acid for 30min, and filtering to obtain filter cake 1 and filtrate 1;
step A: adding hydrochloric acid to decompose filter cake 1, calculating the amount of hydrochloric acid according to CaO in filter cake 1, reacting for 30min, performing thick separation, returning the slurry to acid leaching part, reacting with the thick slurry, and filtering to obtain filtrate 2 containing calcium ion and phosphate ion according to the P content of calcium dihydrogen phosphate2O5Adding phosphoric acid into CaO, stirring uniformly, atomizing, defluorinating, dechlorinating, and dehydrating to obtain qualified calcium dihydrogen phosphate product.
And step B, adding alkaline calcium salt into the filtrate 1 to control the pH value to be 1.2-2.2, carrying out defluorination and impurity removal, then adding alkaline calcium salt to adjust the pH value to be 4.8-6.2, neutralizing to obtain a calcium phosphate product, adjusting the pH value to be 9-11 by the alkaline calcium salt to remove MgO, then adding 98% sulfuric acid to generate calcium sulfate crystals, filtering and washing to obtain high-purity gypsum, and recycling the synchronously generated dilute hydrochloric acid to the dilute acid hydrolysis process to decompose the phosphorite. The results obtained are shown in tables 2 to 6 below.
TABLE 1 index of phosphorus ore
| P2O5 | CaO | MgO | Fe2O3 | Al2O3 | SiO2 | F | SO4 2- | H2O |
| 28.32％ | 40.98％ | 1.58％ | 1.63％ | 1.43％ | 13.84％ | 2.66％ | 0.54％ | 1.00％ |
TABLE 2
TABLE 3
TABLE 4
TABLE 5
TABLE 6
In conclusion, the calcium hydrogen phosphate, the calcium dihydrogen phosphate and the gypsum produced by the method are superior to the national standard.
Claims (9)
1. The method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphorite is characterized by comprising the following steps: the method comprises the following steps:
incompletely decomposing phosphorite with hydrochloric acid with mass concentration of below 15%, and performing solid-liquid separation to obtain solid 1 and liquid 1; wherein the mass ratio P in the solid 12O5/MgO＞6；
A. Treatment of solid 1: reacting the solid 1 with hydrochloric acid, and filtering and separating to obtain filter residue and filtrate 2; mixing the filtrate 2 with phosphoric acid to obtain fine slurry, heating the fine slurry for dechlorination, defluorination and dehydration to obtain calcium phosphate salt; the mass concentration of the hydrochloric acid is more than 5%; the phosphoric acid is added in an amount such that excess calcium is completely converted to calcium phosphate salts; the calcium phosphate salt is calcium hydrogen phosphate, calcium dihydrogen phosphate or monocalcium phosphate; the excessive calcium refers to the residual calcium after the phosphoric acid and the calcium in the filtrate 2 are converted into calcium phosphate salts, when the calcium phosphate salts are monocalcium phosphate, the excessive phosphoric acid is added to completely convert the excessive calcium into monocalcium phosphate, and after the fine slurry is heated for dechlorination, defluorination and dehydration, the residual phosphoric acid is converted into monocalcium phosphate by adding a phosphoric acid neutralizing agent;
B. treatment liquid 1:
adding alkaline calcium salt into the liquid 1 to adjust the pH value to 1.2-2.2, and filtering and separating to obtain a filter cake 3 and a filtrate 3;
secondly, adding alkaline calcium salt into the filtrate 3 to adjust the pH value to 4.8-6.2, and filtering and separating to obtain a filter cake 4 and a filtrate 4, wherein the filter cake 4 is calcium hydrophosphate;
thirdly, adding alkaline calcium salt into the filtrate 4 to adjust the pH value to 9-11, and filtering and separating to obtain a filter cake 5 and a filtrate 5;
fourthly, the filtrate 5 reacts with sulfuric acid to obtain high-purity gypsum and hydrogen chloride or hydrochloric acid.
2. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to claim 1, is characterized in that: in step a, the filtrate 2 is concentrated and then mixed with phosphoric acid.
3. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to claim 1, is characterized in that: in the step A, the solid 1 and hydrochloric acid are in a molar ratio of CaO: HCl to 1: 0.8-3.
4. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to claim 3, characterized in that: and the solid 1 and hydrochloric acid are in a molar ratio of CaO: HCl to 1: 1.6-2.4.
5. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to claim 1 or 3, characterized in that: the mass concentration of the hydrochloric acid is 20-30%.
6. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to any one of claims 1 to 4, characterized in that: in the step A, the heating dechlorination, defluorination and dehydration are realized by any one of negative pressure concentration, drying by an oven, atomization and a disc or a cylinder.
7. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to any one of claims 1 to 4, characterized in that: in the step B, the alkaline calcium salt is at least one of lime or calcium carbonate.
8. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to any one of claims 1 to 4, characterized in that: and step B, the alkaline calcium salt is at least one of lime or calcium carbonate.
9. The method for producing calcium phosphate and high-purity gypsum by using hydrochloric acid and phosphorite according to any one of claims 1 to 4, characterized in that: and step B, the alkaline calcium salt is at least one of quicklime or hydrated lime.
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| CN201711208962.6A CN109836177B (en) | 2017-11-27 | 2017-11-27 | Method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphorite |
| PCT/CN2017/117515 WO2019100498A1 (en) | 2017-11-27 | 2017-12-20 | Method for producing calcium phosphate salt and high purity gypsum with hydrochloric acid and phosphate rock |
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| CN201711208962.6A CN109836177B (en) | 2017-11-27 | 2017-11-27 | Method for producing calcium phosphate salt and high-purity gypsum by using hydrochloric acid and phosphorite |
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| CN111302375A (en) * | 2020-02-27 | 2020-06-19 | 武汉工程大学 | Method for preparing gypsum whisker and composite flame retardant by taking phosphorus tailings as raw materials |
| CN111484020A (en) * | 2020-04-20 | 2020-08-04 | 武汉工程大学 | Tail-free utilization method of high-magnesium phosphate tailings |
| CN111498891A (en) * | 2020-04-20 | 2020-08-07 | 武汉工程大学 | Method for efficiently utilizing calcium, magnesium and phosphorus in high-magnesium phosphorus tailings |
| CN112279227B (en) * | 2020-11-09 | 2023-04-14 | 湖北鄂中生态工程股份有限公司 | Chemical magnesium removal method for collophanite and tailings-free production |
| CN112794346A (en) * | 2021-01-04 | 2021-05-14 | 贵州芭田生态工程有限公司 | Method for simultaneously preparing calcium sulfate, potassium nitrate, potassium magnesium nitrate and magnesium carbonate from calcium magnesium ammonium nitrate liquid |
| CN112758971A (en) * | 2021-01-04 | 2021-05-07 | 贵州芭田生态工程有限公司 | Method for recycling calcium-magnesium-containing leaching solution |
| CN113979414B (en) * | 2021-12-08 | 2023-08-08 | 昆明云盘山农牧科技有限公司 | Production process for preparing feed-grade calcium hydrophosphate by using low-grade phosphorite |
| CN113955731B (en) * | 2021-12-08 | 2024-03-01 | 昆明云盘山农牧科技有限公司 | Preparation method of granular feed-grade monocalcium phosphate |
| CN114956624B (en) * | 2022-06-06 | 2022-11-22 | 瓮福（集团）有限责任公司 | Method for preparing ultrahigh-strength alpha hemihydrate gypsum from industrial byproduct phosphogypsum |
| CN115676788B (en) * | 2022-10-18 | 2024-02-02 | 新希望化工投资有限公司 | High-purity potassium dihydrogen phosphate and preparation method thereof |
| CN116477654A (en) * | 2023-03-31 | 2023-07-25 | 湖北鄂中生态工程股份有限公司 | Harmless treatment method of phosphogypsum |
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| CN1340457A (en) * | 2000-09-01 | 2002-03-20 | 山东鲁北企业集团总公司 | Process for preparing phosphoric acid |
| US6921520B2 (en) * | 2002-10-07 | 2005-07-26 | James C. Barber And Associates Inc. | Process for upgrading raw phosphate ore |
| CN100402418C (en) * | 2004-11-12 | 2008-07-16 | 自贡鸿鹤化工股份有限公司 | Hydrochloric acid process of producing feed level calcium diphosphate and gypsum coproduct |
| CN100396599C (en) * | 2004-12-14 | 2008-06-25 | 自贡鸿鹤化工股份有限公司 | Method for producing phosphorous acid and gypsum using hydrochloric acid method |
| CN1803589A (en) * | 2006-01-25 | 2006-07-19 | 四川省犍为明丰化工有限公司 | Method for producing feed grade dicalcium phosphate and industrial grade phosphoric acid by phosphate ore hydrochloric acid reclamation process |
| CN102583290A (en) * | 2012-02-18 | 2012-07-18 | 张黔生 | Low-grade phosphorite mineral dressing technology and method for producing by-product high-purity gypsum powder |
| CN103496685B (en) * | 2013-10-14 | 2015-09-09 | 四川省化工设计院 | The method of continuous seepage calcium hydrophosphate fodder |
| US20150175424A1 (en) * | 2013-12-23 | 2015-06-25 | Italo Innamorati | Process for the production of phosphoric acid |
| CN104692442B (en) * | 2015-03-17 | 2016-08-31 | 武汉理工大学 | A kind of method utilizing mid low grade phosphate rock association calcium resource to prepare high-purity high-strength Gypsum Fibrosum |
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