CN113683070B - Method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues - Google Patents
Method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues 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
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Abstract
The invention discloses a method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues, which comprises the following steps: (1) mixing materials: uniformly mixing phosphoric acid residues and flotation tailings in a mixer to obtain a solid matter I; (2) calcining: calcining the solid I to obtain a solid II; washing the gas generated by calcining with water and recovering to obtain a fluosilicic acid solution; (3) crushing: and (4) crushing the solid II to obtain the composite multi-element polyphosphate. The beneficial effects of the invention are: the invention realizes the purpose of utilizing the wet-process phosphoric acid residues with high value, obtains the composite multi-element polyphosphate and the fluosilicic acid products with high economic value, has no solid waste and wastewater discharge in the whole production process, discharges a small amount of waste gas after reaching the standard after being washed by water, and has good environmental benefit, economic benefit and social benefit.
Description
Technical Field
The invention relates to the technical field of chemical production, in particular to a method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues.
Background
Phosphoric acid is an important production intermediate product in the industry of phosphorization industry, and can be used as a raw material to produce a series of national production and living necessities, such as fertilizers, industrial phosphates, feed additives, food additives and the like. Phosphoric acid is further divided into hot phosphoric acid and wet phosphoric acid, and compared with the hot phosphoric acid, the wet phosphoric acid has a larger cost advantage, so more and more enterprises choose to use the wet phosphoric acid to produce subsequent products.
At present, the wet-process phosphoric acid production process mainly adopts the reaction of phosphorite and sulfuric acid, the process can be divided into dihydrate, semi-hydrate-dihydrate and the like according to the quantity of by-product gypsum crystal water, the predominant method is dihydrate method, and the obtained phosphoric acid w (P) is 2 O 5 ) The concentration is generally 20% -30%. In order to meet the production requirements of feed-grade calcium phosphate salt and high-concentration phosphorus compound fertilizer, the above-mentioned dilute phosphoric acid is concentrated to w (P) 2 O 5 ) The concentration is 45-50%. As the water evaporates during the concentration process, a large amount of impurities in the phosphoric acid are precipitated, and sludge is formed. The concentrated phosphoric acid can be used as raw material acid for producing feed-grade calcium phosphate salt and high-concentration phosphorus compound fertilizer after further purification treatment such as defluorination, and a certain amount of defluorination precipitate can be separated out in the process.
The concentrated precipitate and defluorinated precipitate are collectively called wet-process phosphoric acid slag, and the main components of the slag are phosphoric acid, calcium sulfate, sodium (potassium) fluosilicate and compound salt formed by combining iron, aluminum, magnesium and phosphorus. How to properly treat wet-process phosphoric acid slag is always a difficult problem for phosphorus chemical enterprises, and some enterprises produce calcium superphosphate by using the wet-process phosphoric acid slag as a raw material, for example, chinese patent document 'a production method for producing calcium superphosphate by using phosphoric acid slag' (application number: 201210457927.9) mixes phosphoric acid slag with phosphorite and sulfuric acid according to a certain proportion to react to obtain calcium superphosphate, for example, chinese patent document 'a comprehensive utilization method for wet-process phosphoric acid slag' (application number: 21410263949.0) washes the phosphoric acid slag by using process water, separates solid and liquid, uses the liquid phase for ammonium phosphate and phosphoric acid extraction sections, and uses sulfuric acid aqueous solution and phosphorite to treat the solid phase to obtain a powdery calcium superphosphate product or to be used as a compound fertilizer raw material.
Although the two methods can treat the phosphoric acid residues, the fluorine resource in the phosphoric acid residues cannot be effectively recovered, and the main product is the superphosphate with serious surplus and low value in the prior art. Compared with the two methods, the second method adds a procedure of recovering phosphoric acid by water washing, and the washed solid phase is used as a raw material for producing ordinary calcium, which is similar to the method for treating the phosphoric acid residue in the 'method for producing the phosphorus-magnesium fertilizer by utilizing wet-process phosphoric acid residue' (application number: 201530452.5), in the Chinese patent document, except that the latter method uses the washed phosphoric acid residue as the raw material to produce the phosphorus-magnesium fertilizer, but the two methods introduce soluble impurities in the phosphoric acid residue into the liquid phase in the process of washing and recovering the phosphoric acid, so that the quality of the fertilizer product or the phosphoric acid is influenced.
There are also methods for preparing compound fertilizers using phosphoric acid residues as raw materials, such as the chinese patent document "a method for preparing nitro compound fertilizers using acid residues in phosphoric acid production" (application No. 201410338769.4), in which phosphoric acid residues and water are first premixed, then nitric acid and ammonia gas are respectively added, and finally, the nitro compound fertilizers are prepared through the procedures of granulation, drying, screening, etc., although the compound fertilizers are prepared using phosphoric acid residues, sodium (potassium) fluosilicate in the phosphoric acid residues is also brought into the compound fertilizers to reduce nutrients, meanwhile, the effective phosphorus of the raw material acid residues is required to be above 40%, and the concentration of the phosphoric acid residues w (P2O 5) of phosphorus chemical enterprises is generally 20% -35%, so the method has a limited popularization range.
In Chinese patent document ' method and device for preparing ammonium phosphate fertilizer by using phosphoric acid sediment ' (application number: 201310321076. X) ' w (P) is added into phosphoric acid sediment 2 O 5 ) After 18% -20% of dilute phosphoric acid, carrying out neutralization reaction with gas ammonia and sulfuric acid, and then carrying out concentration, granulation and other processes to obtain the ammonium phosphate fertilizer.
In addition, in the method for preparing the compound fertilizer by taking the phosphate residues as the raw materials, although the fluorine overflows in a calcining mode to recover the fluorine, because the calcining condition is influenced by the cracking of phosphate molecular chains, if the temperature is too high, the polyphosphate is easy to crack, and if the temperature is too low, some heavy metal elements in tailings cannot be effectively removed, so that the obtained polyphosphate fertilizer is used for the growth of crops, the root growth of the crops is often influenced, and the emergence rate and the acre yield of the crops are influenced.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by using wet-process phosphoric acid residues.
The purpose of the invention is realized by the following technical scheme: a method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues comprises the following steps:
(1) Mixing materials: uniformly mixing phosphoric acid residues and flotation tailings in a mixer to obtain a solid matter I;
(2) And (3) calcining: calcining the solid I to obtain a solid II; washing the gas generated by calcining with water and recovering to obtain a fluosilicic acid solution;
(3) Crushing: crushing the solid II to obtain composite multi-element polyphosphate;
further, the phosphoric acid residue in the step (1) is generated in a wet-process phosphoric acid process, and the composition of the phosphoric acid residue comprises 10-40wt% of P 2 O 5 And 2 to 28wt% F; the composition of the flotation tailings in the step (1) comprises 2-12wt% of P 2 O 5 And 10-21wt% MgO;
further, the composition of the phosphoric acid residue in the step (1) comprises 20 to 35 weight percent of P 2 O 5 And 6 to 21wt% F; the composition of the flotation tailings in the step (1) comprises 3-10wt% of P 2 O 5 And 12-20wt% MgO;
further, in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.5-2.3;
further, in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.7-1.8;
further, the content of fluosilicic acid in the fluosilicic acid solution in the step (2) is 3-19%; the fluosilicic acid solution is further processed into hydrofluoric acid, sodium fluosilicate, sodium fluoride, potassium fluoride or ammonium fluoride;
further, the calcining temperature in the step (2) is 340-550 ℃; the calcination time is 1-4h;
further, mixing and granulating the composite multi-element polyphosphate obtained in the step (3) with potassium sulfate, urea and the like to obtain a special fertilizer for sugarcane or a special fertilizer for potato;
according to a further technical scheme, in the step (2), when the calcining temperature reaches 380-400 ℃, microwave radiation is carried out in the calcining furnace, and when the temperature rises to 400-500 ℃, the microwave radiation is closed, and the temperature is continuously increased.
The invention has the following advantages: the wet-process phosphoric acid residues used in the invention comprise sediments in the concentration process and the defluorination process of the wet-process phosphoric acid, and how to properly treat the two wet-process phosphoric acid residues is a common problem faced by many phosphorus chemical enterprises. The wet-process phosphoric acid residue and phosphoric acid are separated by adopting conventional solid-liquid separation modes such as thickening, plate-and-frame filter pressing, centrifuging and the like, so that newly-added equipment and procedures are avoided. Meanwhile, the separated wet-process phosphoric acid residues can be directly used as a raw material for producing composite multi-element polyphosphate, and the polyphosphate prepared from the wet-process phosphoric acid residues contains various elements required in the growth process of crops such as calcium, magnesium, sulfur, iron, manganese, zinc, silicon and the like in the wet-process phosphoric acid residues, so the polyphosphate is called as the composite multi-element polyphosphate. Compared with other treatment modes, such as water washing for extracting phosphoric acid or adding phosphoric acid for producing calcium superphosphate or compound fertilizer, the method has the advantages of simple process flow and no complex process control unit.
The invention can effectively recover fluorine resources in the wet-process phosphoric acid residues, the fluorine resources mainly come from cryolite, fluorite and phosphate rock at present, and the fluorite is restricted to be exploited as a strategic national resource. In recent years, phosphorus chemical enterprises pay attention to how to improve the recovery rate of fluorine resources in phosphorus chemical industry, and conventional measures include improving the concentration vacuum degree of wet-process phosphoric acid, adding active silicon to promote fluorine in the wet-process phosphoric acid to overflow as much as possible or replacing a fluorine washing nozzle, strengthening the washing effect and increasing the washing rate. However, about 30% of fluorine resources in the phosphate ore still exist in the form of sodium (potassium) fluosilicate in the concentration and precipitationThe slag and the defluorination slag finally enter low-end products, such as calcium superphosphate, agricultural MAP and agricultural DAP, and influence the quality of the products. In the calcining process, the calcining temperature is controlled to be 340-550 ℃ in order to decompose sodium (potassium) fluosilicate in the wet-process phosphoric acid slag as much as possible. In the above calcining temperature range, the sodium (potassium) fluosilicate is SiF 4 And HF overflow, recovery is carried out by adopting a water washing mode, and meanwhile, in the temperature interval, the cracking of polyphosphate is favorably avoided by changing the calcining condition. The method can recover more than 85% of fluorine resources in the wet-process phosphoric acid residues, solves the bottleneck problem of improving the fluorine yield of phosphorus chemical enterprises, and has strong popularization and high economic value.
The invention has the characteristic of treating wastes with wastes, adopts the raw materials which are common waste residues of phosphorus chemical enterprises, does not need to add other raw materials, and embodies the environmental protection and the economical efficiency of the process flow of the invention. The elements such as phosphorus, calcium, magnesium and the like in the composite multi-element polyphosphate produced by the method have good slow release property.
The method comprehensively analyzes the classification and the composition of the wet-process phosphoric acid residues universally existing in phosphorus chemical enterprises, and finds out the common points of different wet-process phosphoric acid residues. The method avoids the existing wet-process phosphoric acid residues as low-end product raw materials or adopts a complex process for treatment, polyphosphate generated by calcining the wet-process phosphoric acid residues and tailings contains various crop nutrient elements such as calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like from the wet-process phosphoric acid residues, and meanwhile, by utilizing the characteristic that the calcining temperature of the polyphosphate accords with the decomposition condition of fluorine-containing compounds in the wet-process phosphoric acid residues, increasingly scarce fluorine resources are recovered, and the maximization of resource utilization is successfully realized.
The method can obtain the powdery composite multi-element polyphosphate product and the fluorosilicic acid water only by three steps of mixing, calcining, washing, absorbing and crushing, and has short process flow and low investment and operation cost.
The raw materials adopted by the invention are wet-process phosphoric acid residues and flotation tailings, the characteristics of 'treating wastes with wastes' are realized, the produced composite multi-element polyphosphate covers various elements required in the growth process of crops such as calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like in the wet-process phosphoric acid residues, the elements such as phosphorus, calcium, magnesium and the like have good slow release property and good economical efficiency, and the low-end products produced by adopting the wet-process phosphoric acid residues are avoided.
The method can effectively recover more than 85% of fluorine resources in the wet-process phosphoric acid residues, and obviously improves the fluorine yield of phosphorus chemical enterprises.
The invention realizes the purpose of utilizing the wet-process phosphoric acid residues with high value, obtains the composite multi-element polyphosphate and fluosilicic acid products with high economic value, has no solid waste and wastewater discharge in the whole production process, discharges a small amount of waste gas after reaching the standard after being washed by water, and has good environmental benefit, economic benefit and social benefit.
Drawings
FIG. 1 is a schematic process flow diagram of the present invention.
FIG. 2 shows a sugarcane special fertilizer prepared from the composite multi-element polyphosphate prepared by the invention.
FIG. 3 shows a potato special fertilizer prepared from the composite multi-element polyphosphate prepared by the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, or orientations or positional relationships that the products of the present invention conventionally lay out when in use, or orientations or positional relationships that are conventionally understood by those skilled in the art, which are merely for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used solely to distinguish one from another, and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1: a method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues comprises the following steps:
(1) Mixing materials: uniformly mixing phosphoric acid residues and flotation tailings in a mixer to obtain a solid matter I;
(2) And (3) calcining: calcining the solid I to obtain a solid II; washing and recovering gas generated by calcination to obtain a fluosilicic acid solution;
(3) Crushing: crushing the solid II to obtain composite multi-element polyphosphate;
the phosphoric acid residue in the step (1) is generated in a wet-process phosphoric acid process, and the composition of the phosphoric acid residue comprises 10-40wt% of P 2 O 5 And 2 to 28wt% F; the composition of the flotation tailings in the step (1) comprises 2-12wt% of P 2 O 5 And 10-21wt% MgO;
the composition of the phosphoric acid residue in the step (1) comprises 20 to 35 weight percent of P 2 O 5 And 6 to 21wt% F; the composition of the flotation tailings in the step (1) comprises 3-10wt% of P 2 O 5 And 12-20wt% MgO;
in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.5-2.3;
in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.7-1.8;
the content of fluosilicic acid in the fluosilicic acid solution in the step (2) is 3-19%; the fluosilicic acid solution is further processed into hydrofluoric acid, sodium fluosilicate, sodium fluoride, potassium fluoride or ammonium fluoride;
the calcination temperature in the step (2) is 340-550 ℃; the calcination time is 1-4h;
mixing and granulating the composite multi-element polyphosphate obtained in the step (3) with potassium sulfate, urea and the like to obtain a special fertilizer for sugarcane or a special fertilizer for potato;
in the step (2), when the calcining temperature reaches 380-400 ℃, microwave radiation is carried out in the calcining furnace, and when the temperature rises to 400-500 ℃, the microwave radiation is closed, and the temperature is continuously raised.
In the calcining process, the calcining temperature is controlled to be 340-550 ℃ in order to decompose sodium (potassium) fluosilicate in the wet-process phosphoric acid slag as much as possible. In the above calcining temperature range, the sodium (potassium) fluosilicate is SiF 4 And HF overflow, recovery is carried out by adopting a water washing mode, and meanwhile, in the temperature interval, the cracking of polyphosphate is favorably avoided by changing the calcining condition. The method can recover more than 85 percent of fluorine resources in the wet-process phosphoric acid residues, solves the bottleneck problem of improving the fluorine yield of phosphorus chemical enterprises, and has strong popularization and economic valueHigh.
The invention has the characteristic of 'treating waste with waste', the adopted raw materials are common waste residues of phosphorus chemical enterprises, other raw materials are not required to be added, and the environmental protection and the economy of the process flow are embodied. The elements such as phosphorus, calcium, magnesium and the like in the composite multi-element polyphosphate produced by the method have good slow release property.
The invention comprehensively analyzes the classification and the composition of the wet-process phosphoric acid residues universally existing in phosphorus chemical enterprises, and finds the common points of different wet-process phosphoric acid residues. The method avoids the existing wet-process phosphoric acid residues as low-end product raw materials or adopts a complex process for treatment, polyphosphate generated by calcining the wet-process phosphoric acid residues and tailings contains various crop nutrient elements such as calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like from the wet-process phosphoric acid residues, and meanwhile, by utilizing the characteristic that the calcining temperature of the polyphosphate accords with the decomposition condition of fluorine-containing compounds in the wet-process phosphoric acid residues, increasingly scarce fluorine resources are recovered, and the maximization of resource utilization is successfully realized.
The method can obtain the powdery composite multi-element polyphosphate product and the fluorosilicic acid water only by three steps of material mixing, calcining, water washing, absorbing and crushing, and has the advantages of short process flow and low investment and operation cost.
The raw materials adopted by the invention are wet-process phosphoric acid residues and flotation tailings, the method has the characteristic of treating waste by waste, the produced composite multi-element polyphosphate covers various elements required by crops in the growth process of calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like in the wet-process phosphoric acid residues, the elements of phosphorus, calcium, magnesium and the like have good slow release property and good economy, and the low-end product produced by using the wet-process phosphoric acid residues is avoided.
The method can effectively recover more than 85% of fluorine resources in the wet-process phosphoric acid residues, and obviously improves the fluorine yield of phosphorus chemical enterprises.
Example 2: (small) a method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues, which comprises the following steps:
(1) Mixing materials: uniformly mixing phosphoric acid residues and flotation tailings in a mixer to obtain a solid I;
(2) And (3) calcining: calcining the solid I to obtain a solid II; washing and recovering gas generated by calcination to obtain a fluosilicic acid solution;
(3) Crushing: crushing the solid II to obtain composite multi-element polyphosphate;
the phosphoric acid residue in the step (1) is generated in a wet-process phosphoric acid process, and the composition of the phosphoric acid residue comprises 10wt% of P 2 O 5 And 2wt% F; the composition of the flotation tailings in the step (1) comprises 2wt% of P 2 O 5 And 10wt% MgO;
the composition of the phosphoric acid residue in the step (1) comprises 20wt% of P 2 O 5 And 6 to 21wt% F; the composition of the flotation tailings in the step (1) comprises 3wt% of P 2 O 5 And 12wt% MgO;
in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.5;
in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.7;
the content of fluosilicic acid in the fluosilicic acid solution in the step (2) is 3-19%; the fluosilicic acid solution is further processed into hydrofluoric acid, sodium fluosilicate, sodium fluoride, potassium fluoride or ammonium fluoride;
the calcination temperature in the step (2) is 340 ℃; the calcination time is 1h;
mixing and granulating the composite multi-element polyphosphate obtained in the step (3) with potassium sulfate, urea and the like to obtain a special fertilizer for sugarcane or a special fertilizer for potato;
in the step (2), when the calcining temperature reaches 380 ℃, microwave radiation is carried out in the calcining furnace, and when the temperature rises to 400 ℃, the microwave radiation is closed, and the temperature is continuously raised.
In the calcining process, the calcining temperature is controlled to be 340-550 ℃ in order to decompose sodium (potassium) fluosilicate in the wet-process phosphoric acid slag as much as possible. In the above calcining temperature range, the sodium (potassium) fluosilicate is SiF 4 And HF overflow, recovery is carried out by adopting a water washing mode, and meanwhile, in the temperature interval, the cracking of polyphosphate is favorably avoided by changing the calcining condition. The inventionMore than 85% of fluorine resources in the wet-process phosphoric acid residues can be recovered, the bottleneck problem of improving the fluorine yield of phosphorus chemical enterprises is solved, and the method is strong in popularization and high in economic value.
The invention has the characteristic of treating wastes with wastes, adopts the raw materials which are common waste residues of phosphorus chemical enterprises, does not need to add other raw materials, and embodies the environmental protection and the economical efficiency of the process flow of the invention. The elements such as phosphorus, calcium, magnesium and the like in the composite multi-element polyphosphate produced by the method have good slow release property.
The invention comprehensively analyzes the classification and the composition of the wet-process phosphoric acid residues universally existing in phosphorus chemical enterprises, and finds the common points of different wet-process phosphoric acid residues. The method avoids the existing wet-process phosphoric acid residues as low-end product raw materials or adopts a complex process for treatment, polyphosphate generated by calcining the wet-process phosphoric acid residues and tailings contains various crop nutrient elements such as calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like from the wet-process phosphoric acid residues, and meanwhile, by utilizing the characteristic that the calcining temperature of the polyphosphate accords with the decomposition condition of fluorine-containing compounds in the wet-process phosphoric acid residues, increasingly scarce fluorine resources are recovered, and the maximization of resource utilization is successfully realized.
The method can obtain the powdery composite multi-element polyphosphate product and the fluorosilicic acid water only by three steps of mixing, calcining, washing, absorbing and crushing, and has short process flow and low investment and operation cost.
The raw materials adopted by the invention are wet-process phosphoric acid residues and flotation tailings, the characteristics of 'treating wastes with wastes' are realized, the produced composite multi-element polyphosphate covers various elements required in the growth process of crops such as calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like in the wet-process phosphoric acid residues, the elements such as phosphorus, calcium, magnesium and the like have good slow release property and good economical efficiency, and the low-end products produced by adopting the wet-process phosphoric acid residues are avoided.
The method can effectively recover more than 85% of fluorine resources in the wet-process phosphoric acid residues, and obviously improves the fluorine yield of phosphorus chemical enterprises.
Example 3: a method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by using wet-process phosphoric acid residues comprises the following steps:
(1) Mixing materials: uniformly mixing phosphoric acid residues and flotation tailings in a mixer to obtain a solid I;
(2) And (3) calcining: calcining the solid I to obtain a solid II; washing the gas generated by calcining with water and recovering to obtain a fluosilicic acid solution;
(3) Crushing: crushing the solid II to obtain composite multi-element polyphosphate;
the phosphoric acid residue in the step (1) is generated in a wet-process phosphoric acid process, and the composition of the phosphoric acid residue comprises 40wt% of P 2 O 5 And 28wt% F; the composition of the flotation tailings in the step (1) comprises 12wt% of P 2 O 5 And 21wt% MgO;
the composition of the phosphoric acid residues in the step (1) comprises 35wt% of P 2 O 5 And 21wt% F; the composition of the flotation tailings in the step (1) comprises 10wt% of P 2 O 5 And 20wt% MgO;
in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =2.3;
in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =1.8;
the content of fluosilicic acid in the fluosilicic acid solution in the step (2) is 3-19%; the fluosilicic acid solution is further processed into hydrofluoric acid, sodium fluosilicate, sodium fluoride, potassium fluoride or ammonium fluoride;
the calcination temperature in the step (2) is 550 ℃; the calcination time is 4h;
mixing and granulating the composite multi-element polyphosphate obtained in the step (3) with potassium sulfate, urea and the like to obtain a special fertilizer for sugarcane or a special fertilizer for potato;
in the step (2), when the calcining temperature reaches 400 ℃, microwave radiation is carried out in the calcining furnace, and when the temperature rises to 500 ℃, the microwave radiation is turned off, and the temperature is continuously raised.
In the calcining process, the calcining temperature is controlled to be 340-550 ℃ in order to decompose sodium (potassium) fluosilicate in the wet-process phosphoric acid slag as much as possible. In the above calcining temperature range, the sodium (potassium) fluosilicate is SiF 4 And HF form overflowAnd the polyphosphate is recovered by adopting a water washing mode, and the cracking of the polyphosphate is favorably avoided by changing the calcining condition in the temperature range. The method can recover more than 85% of fluorine resources in the wet-process phosphoric acid residues, solves the bottleneck problem of improving the fluorine yield of phosphorus chemical enterprises, and has strong popularization and high economic value.
The invention has the characteristic of treating wastes with wastes, adopts the raw materials which are common waste residues of phosphorus chemical enterprises, does not need to add other raw materials, and embodies the environmental protection and the economical efficiency of the process flow of the invention. The elements such as phosphorus, calcium, magnesium and the like in the composite multi-element polyphosphate produced by the method have good slow release property.
The invention comprehensively analyzes the classification and the composition of the wet-process phosphoric acid residues universally existing in phosphorus chemical enterprises, and finds the common points of different wet-process phosphoric acid residues. The method avoids the existing wet-process phosphoric acid residues as low-end product raw materials or adopts a complex process for treatment, polyphosphate generated by calcining the wet-process phosphoric acid residues and tailings contains various crop nutrient elements such as calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like from the wet-process phosphoric acid residues, and simultaneously utilizes the characteristic that the calcining temperature of the polyphosphate accords with the decomposition condition of fluorine-containing compounds in the wet-process phosphoric acid residues to recover increasingly scarce fluorine resources, thereby successfully realizing the maximization of resource utilization.
The method can obtain the powdery composite multi-element polyphosphate product and the fluorosilicic acid water only by three steps of material mixing, calcining, water washing, absorbing and crushing, and has the advantages of short process flow and low investment and operation cost.
The raw materials adopted by the invention are wet-process phosphoric acid residues and flotation tailings, the characteristics of 'treating wastes with wastes' are realized, the produced composite multi-element polyphosphate covers various elements required in the growth process of crops such as calcium, magnesium, sulfur, silicon, iron, manganese, zinc and the like in the wet-process phosphoric acid residues, the elements such as phosphorus, calcium, magnesium and the like have good slow release property and good economical efficiency, and the low-end products produced by adopting the wet-process phosphoric acid residues are avoided.
The method can effectively recover more than 85% of fluorine resources in the wet-process phosphoric acid residues, and obviously improves the fluorine yield of phosphorus chemical enterprises.
Example 4:
the detection indexes of the wet-process phosphoric acid residues (concentrated residues) and the flotation tailings are shown in the following table 1.
TABLE 1 indexes for detection of wet process phosphoric acid sludge (concentrate sludge) and flotation tailings used in example 4
| Total P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | SO 3 （wt%） | F（wt%） | |
| Phosphoric acid slag | 23.53 | 7.92 | 2.87 | 14.41 | 12.31 |
| Flotation of tailings | 6.12 | 29.89 | 13.89 | 1.55 | 1.66 |
Uniformly mixing the wet-process phosphoric acid residues and the flotation tailings according to the weight ratio of 5: the molar ratio of (Mg + Ca-S) is 1.71. And calcining the solid I in a rotary drying kiln at the temperature of 360 ℃ for 1.2 hours to obtain a blocky solid II. Collecting gas generated in the calcining process, and absorbing and treating the gas by adopting a water washing mode to obtain fluorosilicic acid water containing 11% of fluorosilicic acid.
And crushing the massive solid II to obtain powdery composite multi-element polyphosphate, wherein the detection indexes are shown in the following table 2.
Table 2 detection index of composite multi-element polyphosphate obtained in example 4
| Total P 2 O 5 （wt%） | Effective P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | F（wt%） | MnO（wt%） | SiO 2 （wt%） | Zn（wt%） | S（wt%） | |
| Composite multi-element polyphosphate | 37.24 | 36.61 | 18.42 | 10.33 | 1.10 | 0.2 | 6.29 | 0.006 | 3.24 |
The fluorine yield in the wet-process phosphoric acid residues is 86.42 percent, the polymerization rate of the composite multi-element polyphosphate is 82 percent, and the polymerization degree is 2.81 as measured by fluorine balance calculation and product detection.
Example 5:
the detection indexes of the wet-process phosphoric acid residues (defluorination residues) and the flotation tailings are shown in the following table 3.
TABLE 3 indexes for detection of wet process phosphoric acid residue (defluorination residue) and flotation tailings used in example 5
| Total P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | SO 3 （wt%） | F（wt%） | |
| Phosphoric acid slag | 28.31 | 4.46 | 3.01 | 3.68 | 20.49 |
| Flotation of tailings | 4.47 | 37.71 | 18.22 | 1.29 | 1.47 |
Uniformly mixing the wet-process phosphoric acid residues and the flotation tailings according to the weight ratio of 3: the molar ratio of (Mg + Ca-S) was 0.88. And (3) calcining the solid I in a rotary drying kiln at the temperature of 430 ℃ for 1.5h to obtain a blocky solid II. Collecting gas generated in the calcining process, and absorbing and treating the gas by adopting a water washing mode to obtain fluorosilicic acid water containing 13% of fluorosilicic acid.
And crushing the massive solid II to obtain powdery composite multi-element polyphosphate, wherein the detection indexes are shown in the following table 4.
TABLE 4 detection index of composite multielement polyphosphate obtained in example 5
| Total P 2 O 5 （wt%） | Effective P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | F（wt%） | MnO（wt%） | SiO 2 （wt%） | Zn（wt%） | S（wt%） | |
| Composite multi-element polyphosphate | 42.28 | 41.90 | 19.26 | 11.32 | 0.98 | 0.16 | 9.41 | 0.004 | 3.01 |
The fluorine yield of the wet-process phosphoric acid residue is 88.27 percent, the polymerization rate of the composite multi-element polyphosphate is 85 percent, and the polymerization degree is 3.11 as measured by fluorine balance calculation and product detection.
Example 6:
the detection indexes of the wet-process phosphoric acid residues (defluorination residues and defluorination residues) and the flotation tailings are shown in the following table 5.
TABLE 5 detection indexes of wet-process phosphoric acid residues (defluorination residues and defluorination residues) and flotation tailings selected in example 6
| Total P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | SO 3 （wt%） | F（wt%） | |
| Phosphoric acid slag | 25.81 | 5.74 | 2.99 | 8.90 | 15.26 |
| Flotation of tailings | 8.35 | 33.76 | 13.53 | 5.28 | 1.72 |
Uniformly mixing the wet-process phosphoric acid residues and the flotation tailings according to a weight ratio of 4: the molar ratio of (Mg + Ca-S) is 1.36. And (3) calcining the solid I in a rotary drying kiln at the temperature of 450 ℃ for 2 hours to obtain a blocky solid II. Collecting gas generated in the calcining process, and absorbing and treating the gas by adopting a water washing mode to obtain fluorosilicic acid water containing 12% of fluorosilicic acid.
And crushing the massive solid II to obtain powdery composite multi-element polyphosphate, wherein the detection indexes are shown in the following table 6.
TABLE 6 detection index of composite multielement polyphosphate obtained in example 6
| Total P 2 O 5 （wt%） | Effective P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | F（wt%） | MnO（wt%） | SiO 2 （wt%） | Zn（wt%） | S（wt%） | |
| Composite multi-element polyphosphate | 43.32 | 42.98 | 20.01 | 10.99 | 0.84 | 0.18 | 8.72 | 0.0072 | 3.85 |
The fluorine yield of the wet-process phosphoric acid residues is 86.26%, the polymerization rate of the composite multi-element polyphosphate is 87%, and the polymerization degree is 3.24, which is measured by fluorine balance calculation and product detection.
Example 7:
the detection indexes of the wet-process phosphoric acid residues (concentrated residues) and the flotation tailings are shown in the following table 7.
TABLE 7 index for wet-process phosphoric acid residue (concentrate) and flotation tailings detection
| Total P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | SO 3 （wt%） | F（wt%） | |
| Phosphoric acid slag | 30.74 | 6.33 | 2.01 | 13.12 | 11.26 |
| Flotation of tailings | 5.01 | 35.20 | 17.45 | 4.79 | 2.02 |
Uniformly mixing the wet-process phosphoric acid residues and flotation tailings according to a weight ratio of 4: the molar ratio of (Mg + Ca-S) was 0.94. And calcining the solid I in a rotary drying kiln at 510 ℃ for 3 hours to obtain a blocky solid II. Collecting gas generated in the calcining process, and absorbing and treating the gas by adopting a water washing mode to obtain fluorosilicic acid water containing 15 percent of fluorosilicic acid.
And crushing the massive solid II to obtain powdery composite multi-element polyphosphate, wherein the detection indexes are shown in the following table 8.
TABLE 8 detection index of composite multielement polyphosphate obtained in example 7
| Total P 2 O 5 （wt%） | Effective P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | F（wt%） | MnO（wt%） | SiO 2 （wt%） | Zn（wt%） | S（wt%） | |
| Composite multi-element polyphosphate | 44.25 | 44.01 | 21.32 | 11.03 | 0.77 | 0.19 | 8.13 | 0.006 | 4.12 |
The fluorine yield of the wet-process phosphoric acid residue is 89.32%, the polymerization rate of the composite multi-element polyphosphate is 90%, and the polymerization degree is 4.05, which is measured by fluorine balance calculation and product detection.
Example 8 field test 1
The field test is carried out in the test field of Jiang Haote Wuchuan county in inner Mongolia 4 months in 2020.
The raw materials used in the test are all common commercial products: potassium sulfate (K) 2 O 52%）Urea (total N46.4%), potassium humate (organic matter 75%), zinc sulfate heptahydrate (Zn 21.5%), triple superphosphate (effective P) 2 O 5 44%), calcium superphosphate (available P) 2 O 5 18%）。
The test procedure was as follows:
test set # 1: 30kg of heavy superphosphate, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate and 0.1kg of zinc sulfate heptahydrate are applied as base fertilizers.
Test set # 2: 30kg of calcium superphosphate, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate and 0.1kg of zinc sulfate heptahydrate are applied as base fertilizers.
Test set # 3: 28kg of the composite multi-element polyphosphate prepared in example 4, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate, and 0.1kg of zinc sulfate heptahydrate were applied as base fertilizers.
Test set # 4: 28kg of the composite multi-element polyphosphate prepared in example 7, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate and 0.1kg of zinc sulfate heptahydrate were applied as base fertilizers.
The potato type used in the test is the Hissen No. 6, each group of tests is repeated for 4 times, the emergence rate and the acre yield of the test are counted, and the statistical results are shown in the following table 9.
TABLE 9 statistical results of field test 1
| Rate of emergence (%) | Rate of increase in emergence (%) | Mu yield (Kg) | Proportion of increase in production | |
| Test group No. 1 | 80.14 | --- | 2980 | --- |
| Test group No. 2# | 81.45 | 1.63 | 3148 | 5.64 |
| Test group No. 3 | 85.79 | 7.05 | 3463 | 16.21 |
| Test group 4# | 87.11 | 8.70 | 3592 | 20.54 |
The data in the table show that the composite multi-element polyphosphate prepared by the invention has the effects of obviously increasing the rate of emergence and increasing the yield compared with triple superphosphate and superphosphate. In addition, since the polyphosphate used in test 4 has a higher polymerization rate than that used in test 3, the rate of increase of emergence and the yield per mu were more advantageous.
And (3) fluosilicic acid yield test:
the test is completed on a small test device built by Zhonghuayunlong Co., ltd, hongming county, in 2020 and 10 months, and the device is an equal-proportion reduction of the existing whole plant production device, and the reduction rate is more than 95%.
Fluorine yield to 1 ton per P produced 2 O 5 And (wet-process phosphoric acid) is recycled, and the quantity of the recovered 100% fluorosilicic acid is calculated.
The test data shows that:
experiment 1 is a reduction simulation of the existing wet-process phosphoric acid production and subsequent product processes, and the fluosilicic acid yield is 58.9kg/tP 2 O 5 The actual production data are matched;
experiment 2 on the basis of reducing the existing process, the wet-process phosphoric acid slag (concentrated slag and defluorination slag) generated in the experiment process is used as the raw material to prepare the compound multi-element polyphosphate and recover the fluosilicic acid, and the yield of the fluosilicic acid is 93.7kg/tP 2 O 5 。
The data show that the yield of the fluosilicic acid is obviously increased and the increase rate reaches 59.08 percent when the invention is adopted to comprehensively treat the wet-process phosphoric acid slag.
Example 9:
the procedure used to prepare the powdered multi-element polyphosphate salt was carried out as in example 7, except that during calcination, microwave irradiation was stopped when the temperature was raised to 400 ℃ in the calciner, and then the temperature was raised to 500 ℃ and then the temperature was maintained at 510 ℃ for 3 hours to obtain the bulk solid ii.
And crushing the blocky solid II to obtain powdery composite multi-element polyphosphate, wherein the detection indexes are shown in the following table 10.
TABLE 10 detection index of composite multielement polyphosphate obtained in example 9
| Total P 2 O 5 （wt%） | Effective P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | F（wt%） | As（wt%） | |
| Composite multi-element polyphosphate | 58.6 5 | 56.0 1 | 19.32 | 16.03 | 1.81 | 0.00012 |
Example 10:
powdered composite multielement polyphosphate was prepared by the method of example 7, the only difference is that during calcination, microwave irradiation was carried out in the calciner when the temperature was raised to 400 ℃, the microwave irradiation was stopped when the temperature was raised to 540 ℃, and calcination was carried out for 3h at this temperature after the temperature was raised to 550 ℃ to obtain a bulk solid ii.
And crushing the massive solid II to obtain powdery composite multi-element polyphosphate, wherein the detection indexes are shown in the following table 11.
TABLE 11 detection of the composite multielement polyphosphate obtained in example 10
| Total P 2 O 5 （wt%） | Effective P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | F（wt%） | As（wt%） | |
| Composite multi-element polyphosphate | 44.6 5 | 43.0 1 | 19.22 | 14.08 | 1.03 | 0.00010 |
Example 11:
a powdery composite multi-element polyphosphate was prepared in the same manner as in example 10 except that the microwave irradiation was not performed in the calciner during the calcination. After the temperature is raised to 550 ℃, the temperature is kept for calcining for 3 hours, and the blocky solid II is obtained.
And crushing the massive solid II to obtain powdery composite multi-element polyphosphate, wherein the detection indexes are shown in the following table 12.
TABLE 12 detection of composite multielement polyphosphate obtained in example 11
| Total P 2 O 5 （wt%） | Effective P 2 O 5 （wt%） | CaO（wt%） | MgO（wt%） | F（wt%） | As（wt%） | |
| Composite multi-element polyphosphate | 38.26 | 38.0 1 | 16.29 | 10.08 | 1.01 | 0.00025 |
It can be known from examples 10, 11, and 12 that too high temperature of calcination affects the cracking of polyphosphate, thereby being not beneficial to the generation of polyphosphate, but in the process of raising the temperature, the microwave radiation in the calcination furnace is performed when reaching a certain high temperature, so that the cracking of polyphosphate can be favorably hindered, arsenic can be favorably overflowed, and the content of arsenic in tailings in polyphosphate can be favorably reduced.
Example 13 field test 2
The same field test method as in example 8 was used
The test procedure was as follows:
test set # 1: 30kg of heavy calcium superphosphate, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate and 0.1kg of zinc sulfate heptahydrate are applied as base fertilizers.
Test set # 2: 30kg of calcium superphosphate, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate and 0.1kg of zinc sulfate heptahydrate are applied as base fertilizers.
Test set # 3: 28kg of the composite multi-element polyphosphate prepared in example 9, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate and 0.1kg of zinc sulfate heptahydrate were applied as base fertilizers.
Test set # 4: 28kg of the composite multi-element polyphosphate prepared in example 10, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate and 0.1kg of zinc sulfate heptahydrate were applied as base fertilizers.
Test group 54#: 28kg of the composite multi-element polyphosphate prepared in example 11, 33kg of urea, 38kg of potassium sulfate, 0.5kg of potassium humate, and 0.1kg of zinc sulfate heptahydrate were applied as base fertilizers.
The potato type used in the test is the Hessen No. 6, each group of tests is repeated for 4 times, the emergence rate and the acre yield of the test are counted, and the statistical results are shown in the following table 12.
Table 12 field trial 2 statistical results
| Percentage of emergence (%) | Rate of increase in emergence (%) | Mu yield (Kg) | Proportion of increase in production | |
| Test group No. 1 | 80.14 | --- | 2980 | --- |
| Test group No. 2 | 81.45 | 1.63 | 3148 | 5.64 |
| Test group No. 3# | 92.87 | 11.70 | 4092 | 20.54 |
| Test group 4# | 88.79 | 9.05 | 3569 | 16.21 |
| Test group 5# | 80.94 | 1.34 | 2997 | 5.98 |
From the results in table 12, it can be seen that, in the temperature rise process of the calcination process, after microwave radiation is performed in the calcination furnace, the overflow of arsenic is facilitated, and the prepared composite multi-element polyphosphate salt is used for preparing the fertilizer special for potatoes, which is more conducive to the improvement of the rate of emergence and the per mu yield. The composite multi-element polyphosphate prepared in the example 9 has high content, namely, the composite multi-element polyphosphate depends on the proper control of the raw material ratio, is also derived from proper calcining temperature and calcining condition, is favorable for protecting the polyphosphate from cracking, and simultaneously, arsenic contained in tailings is removed under the environment of high temperature and microwave radiation, so that the composite multi-element polyphosphate is favorable for the growth of potato seedlings.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing embodiments, or equivalents may be substituted for elements thereof.
Claims (4)
1. A method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by wet-process phosphoric acid residues is characterized by comprising the following steps:
(1) Mixing materials: uniformly mixing phosphoric acid residues and flotation tailings in a mixer to obtain a solid I;
(2) And (3) calcining: calcining the solid I to obtain a solid II; washing the gas generated by calcining with water and recovering to obtain a fluosilicic acid solution;
(3) Crushing: crushing the solid II to obtain composite multi-element polyphosphate;
the composition of the phosphoric acid residues in the step (1) comprises 20 to 35 weight percent of P 2 O 5 And 6 to 21wt% F; the composition of the flotation tailings in the step (1) comprises 3-10wt% of P 2 O 5 And 12-20wt% MgO;
the calcination temperature in the step (2) is 340-550 ℃; the calcination time is 1-4h; when the calcining temperature reaches 380-400 ℃, performing microwave radiation in the calcining furnace, and when the temperature rises to 400-500 ℃, closing the microwave radiation and continuing to heat;
and (4) mixing and granulating the composite multi-element polyphosphate obtained in the step (3) with potassium sulfate, urea and the like to obtain the special fertilizer for sugarcane or the special fertilizer for potato.
2. The method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by using the wet-process phosphoric acid residues as claimed in claim 1, is characterized in that: in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.5-2.3.
3. The method for producing composite multi-element polyphosphate and co-producing fluosilicic acid from wet-process phosphoric acid residues as claimed in claim 2, wherein the method comprises the following steps: in the step (1), the molar ratio of phosphorus to metal elements in the solid I is P (Mg + Ca-S) =0.7-1.8.
4. The method for producing composite multi-element polyphosphate and co-producing fluosilicic acid by using the wet-process phosphoric acid residues as claimed in claim 1, wherein the method comprises the following steps: the content of fluosilicic acid in the fluosilicic acid solution in the step (2) is 3-19%; the fluorosilicic acid solution is used for further processing into hydrofluoric acid, sodium fluorosilicate, sodium fluoride, potassium fluoride or ammonium fluoride.
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