CN114276170B - Method for preparing calcium magnesium phosphate fertilizer and co-producing ferro-phosphorus and phosphorus-containing product prepared by method - Google Patents
Method for preparing calcium magnesium phosphate fertilizer and co-producing ferro-phosphorus and phosphorus-containing product prepared by method Download PDFInfo
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Abstract
The invention provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus and a phosphorus-containing product prepared by the method, wherein the method comprises the following steps: heating sludge to obtain a molten prefabricated material; (II) separating the prefabricated material in the step (I) to obtain a first mixture and a second mixture, and respectively cooling the first mixture and the second mixture; and (III) respectively carrying out post-treatment on the first mixture and the second mixture cooled in the step (II) to obtain the calcium magnesium phosphate fertilizer and the ferrophosphorus. The invention has few byproducts in the preparation process, and the sludge is completely converted into a final product, thereby fully realizing the reduction, stabilization and harmlessness of the sludge.
Description
Technical Field
The invention belongs to the technical field of sludge treatment, and relates to a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus and a phosphorus-containing product prepared by the method.
Background
Phosphorus plays a very important role in the life activities of human beings, animals and plants and is a nutrient necessary for the growth and development of plants. Phosphorus is a limited non-renewable resource, and it is estimated that the worldwide storage of phosphate ore is only enough for human use for about 100 years, and the phosphorus-rich ore which can be economically exploited in China is presumed to last for only 10 years. The increasing depletion of phosphorus resources has become a major crisis that must be addressed in today's society. 25 percent of phosphorus entering into biological circulation is discharged into a sewage treatment plant, about 90 percent of phosphorus in the sewage is transferred into municipal sludge after advanced treatment, and the municipal sludge has great potential for recycling phosphorus resources. However, heavy metals and pathogenic bacteria contained in the municipal sludge can cause serious soil pollution, and meanwhile, the inorganic substance occurrence structure in the municipal sludge determines that the phosphorus content absorbable by plants is low (about 40%), so that the direct application not only can cause ecological pollution, but also can cause a large amount of phosphorus resource loss. Therefore, municipal sludge must be further treated to be useful for plant utilization in agriculture, gardens, etc., and soil improvement.
At present, the mainstream research direction of the municipal sludge phosphorus recovery process in China is wet-process phosphorus recovery, and the common process flow is as follows: phosphorus in municipal sludge or municipal sludge ash is dissolved out through a strong acid, strong alkali or hydrothermal environment, and then the phosphorus is converted into a form which can be absorbed and utilized by plants in a liquid phase.
CN111548197A discloses a method for recovering calcium phosphate fertilizer from municipal sludge incineration bottom ash. The method comprises the following steps: drying municipal sludge incineration bottom ash, mixing the dried municipal sludge incineration bottom ash with a hydrochloric acid solution, stirring and filtering to obtain a phosphorus-rich extracting solution; adding calcium hydroxide into the phosphorus-rich extracting solution, carrying out reaction, evaporation and concentration, cooling at room temperature for crystallization, filtering, collecting upper crystals, and air-drying the crystals to obtain the phosphate fertilizer.
CN111646674A discloses a method for releasing and recovering phosphorus in municipal sludge, which mainly comprises the following steps: firstly, pretreating municipal sludge to obtain dry municipal sludge, incinerating the prepared dry municipal sludge to obtain municipal sludge incineration ash, adding an extracting agent into the incineration ash, and performing centrifugal treatment under the condition of a certain liquid-solid ratio to obtain a phosphorus-rich supernatant; carrying out fine purification treatment on the phosphorus-rich supernatant; taking the supernatant after the fine purification treatment to adjust the pH, adding MgCl 2 ·6H 2 And O, obtaining a phosphorization precipitate.
CN112279478A discloses a method for recovering phosphorus in excess municipal sludge in the form of vivianite, which specifically comprises the following steps: naturally settling municipal sludge to obtain a municipal sludge concentrated sample, adding ferric chloride, and performing anaerobic fermentation; adjusting the pH value of the fermented supernatant to 7, naturally settling and recovering precipitates to obtain the pyrite crystal.
The wet-process phosphorus recovery process product has high phosphorus availability. However, such a method has the following problems: (1) the municipal sludge is not thoroughly treated, the volume reduction effect of the municipal sludge is poor due to a large amount of residual solids after phosphorus release, and a large amount of waste liquid rich in heavy metals and acid and alkali generated in the process of recovering phosphorus belongs to factors harmful to the environment and the human health and needs to be strictly treated subsequently. (2) The recovery rate of phosphorus is lower, and the recovery rate of the wet-process phosphorus recovery process is 40-80%. The recovery rate of phosphorus in the sludge treated by the thermal method is up to more than 95 percent, the phosphorus resource in the sludge can be completely utilized, the organic pollutants in the sludge are completely eliminated, and the volume reduction effect is obvious. However, the complex process results in less research and achievement related to the phosphorus recovery by the sludge thermal method, and the process is immature. The calcium magnesium phosphate fertilizer is one kind of hot phosphate fertilizer and its production process may be referred to. However, the components and properties of the sludge are different from those of phosphate ore, and the content of elements such as iron, aluminum and the like is high, so that the sludge is difficult to be directly used for phosphorus recovery by a sludge thermal method.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for preparing calcium magnesium phosphate and co-producing ferro-phosphorus and a phosphorus-containing product prepared by the method, so that the reduction, stabilization and harmlessness of sludge are realized, elements such as phosphorus, silicon, calcium, magnesium and the like in the sludge are recovered to prepare the calcium magnesium phosphate, the recovery rate of phosphorus is more than 90%, the prepared calcium magnesium phosphate meets the performance index requirements of the national standard GB/T20412-2006 of the calcium magnesium phosphate, and the byproduct ferro-phosphorus meets the performance index requirements of the ferro-phosphorus industry standard YB/T5036-2012.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus, the method comprising the steps of:
heating sludge to obtain a molten prefabricated material;
(II) separating the prefabricated material in the step (I) to obtain a first mixture and a second mixture, and respectively cooling the first mixture and the second mixture;
and (III) respectively carrying out post-treatment on the first mixture and the second mixture cooled in the step (II) to obtain the calcium magnesium phosphate fertilizer and the ferrophosphorus.
According to the method for preparing the calcium magnesium phosphate fertilizer and co-producing the ferro-phosphorus, few byproducts are generated in the preparation process, sludge is completely converted into a final product, and the reduction, stabilization and harmlessness of the sludge are fully realized; the invention recovers elements such as phosphorus, silicon, calcium and magnesium in the sludge to prepare the calcium magnesium phosphate fertilizer, and the recovery rate of the phosphorus is more than 90 percent; meanwhile, a large amount of iron in the sludge is converted into high-value ferrophosphorus, so that the economic benefit of the process is obviously improved, the process has good social benefit and economic benefit, the process flow is simple, large-scale construction and production are easy to carry out, and the industrial application prospect is good.
In a preferred embodiment of the present invention, in step (i), the composition of the sludge includes any one or a combination of at least two of phosphorus, silicon, calcium, and magnesium.
Preferably, the sludge comprises any one of or a combination of at least two of municipal sludge, sludge coal, sludge gasification slag or sludge ash.
The sludge source in the invention includes municipal sludge produced by a sewage treatment plant, sludge charcoal obtained after carbonization treatment of the municipal sludge, sludge gasification slag obtained after gasification of the municipal sludge, and sludge ash obtained after incineration of the municipal sludge.
Preferably, when the sludge is sludge ash, the reducing agent is added into the prefabricated material.
Preferably, the reducing agent is coke.
Preferably, the mass of the reducing agent is 5% to 20% of the mass of the sludge, and may be, for example, 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, or 20%, but is not limited to the recited values, and other values not recited within the range of values are also applicable.
As a preferred technical scheme of the invention, in the step (I), auxiliary materials are added into the sludge.
Preferably, the composition of the adjuvant comprises any one or a combination of at least two of calcium, magnesium or phosphorus.
Preferably, the supplementary material comprises minerals and/or solid waste.
Preferably, the mineral comprises a mineral containing an alkaline earth metal element and/or a mineral containing a phosphorus element.
Preferably, the alkaline earth element-containing mineral includes any one of serpentine, dolomite or olivine or a combination of at least two thereof.
In the present invention, the alkaline earth metal element-containing mineral refers to a mineral containing calcium and magnesium, and can be mixed with a sludge raw material as an auxiliary material to produce a calcium-magnesium phosphate fertilizer, the serpentine refers to a hydrous magnesium-rich silicate mineral, and the chemical component of the dolomite is CaMg (CO) 3 ) 2 The crystal belongs to trigonal carbonate mineral, and the composition of the olivine is mainly Mg 2 SiO 4 And Fe 2 SiO 4 And also contains a small amount of Ca 2+ And Mn 2+ Can be used as an auxiliary material to be added into sludge for preparing the phosphorus-containing fertilizer.
Preferably, the minerals containing elemental phosphorus include phosphate ore and/or phosphate tailings.
Preferably, the solid waste comprises solid waste containing alkaline earth metal elements and/or solid waste containing phosphorus elements.
Preferably, the solid waste containing alkaline earth metal elements comprises any one of or a combination of at least two of boron sludge, chromium slag and carbide slag.
The boric sludge is waste residue generated in the production of boric acid, borax and other products, and has the main chemical components of MgO and SiO 2 And contains a certain amount of Fe 2 O 3 、B 2 O 3 And small amounts of CaO and Al 2 O 3 The chromium slag is waste slag generated in the process of producing metal chromium and chromium salt, and the main minerals contained in the chromium slag comprise periclase (MgO) and calcium silicate (2 CaO. SiO) 2 ) Brucite (4 CaO. Al) 2 O 3 ·Fe 2 O 3 ) The calcium carbide slag is industrial waste generated in the process of generating acetylene gas by reacting calcium carbide with water, contains a large amount of calcium oxide and a small amount of silicon, iron, aluminum, calcium, magnesium and carbon slag, and is a good calcium auxiliary material for producing the calcium magnesium phosphate fertilizer.
Preferably, the solid waste containing phosphorus element comprises any one or a combination of at least two of animal bone meal, livestock manure or phosphorus-containing fungi residues.
The animal bone powder contains inorganic components such as calcium, phosphorus and the like, the animal manure contains inorganic nutrients such as nitrogen, phosphorus, potassium and the like, the animal manure can be used as a nitrogen source or a phosphorus source for preparing fertilizers and is added into sludge to prepare nitrogen fertilizers or phosphorus fertilizers, and the mushroom dregs contain rich nitrogen, phosphorus and organic matters, and also contain trace elements such as iron, calcium, zinc, magnesium and the like, so that the animal bone powder can be used as a good auxiliary material.
As a preferred technical scheme of the invention, in the step (I), the mole fraction ratio of phosphorus, silicon, calcium and magnesium elements in the prefabricated material is P 2 O 5 :SiO 2 Examples of the inorganic oxide include 1:1 to 5:2.5 to 10:1.5 to 5, for example, 1:1:2.5:1.5, 1:2:2:2, 1:3:5:3, 1:3.5:7:2.1, 1:4:6:4, 1:2:8:5, 1:3:2.5:1.5, 1:3:7:2.5, 1:2.65:6:2, 1:4:9:4.5, and 1:5:10:5, but the inorganic oxide is not limited to the listed values, and other non-listed values in the above range are also applicable.
Preferably, the mass percentage of the sludge in the prefabricated material is 50% to 100%, for example, 50%, 55%, 60%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
Preferably, P in the preformed material 2 O 5 The mass percentage of the component (a) is more than or equal to 12 percent.
It should be noted that, in the present invention, before mixing the sludge and the auxiliary materials, it is first required to detect each component and content of the sludge and the auxiliary materials as raw materials, and then calculate a reasonable adding ratio of the sludge and the auxiliary materials, and then add the auxiliary materials containing calcium, magnesium, phosphorus, etc. to the sludge according to the ratio, and adjust the composition of the mixture entering the furnace to the expected value and then mix the mixture.
In a preferred embodiment of the present invention, in the step (i), the heating temperature is 1000 to 1500 ℃, and may be, for example, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃, 1200 ℃, 1250 ℃, 1300 ℃, 1350 ℃, 1400 ℃, 1450 ℃, or 1500 ℃, but is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.
It should be noted that, in the invention, after the sludge and the auxiliary materials are mixed at a certain temperature, the mixture is heated to a molten state, when the heating temperature is too high, the volatilization of phosphorus in the mixture can be caused, the phosphorus in the product is reduced, and the standard is not easily reached; when the heating temperature is too low, the mixture cannot reach a molten phase, the layering is difficult, and the recovery of the calcium magnesium phosphate fertilizer and the ferro-phosphorus is difficult to realize.
Preferably, the heating time is 20 to 120min, for example, 20min, 30min, 40min, 45min, 50min, 55min, 60min, 70min, 80min, 90min, 100min, 110min, 115min or 120min, but is not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, said heating is carried out in a furnace.
Preferably, the furnace comprises any one of a blast furnace, a natural gas furnace, an electric furnace or a plasma furnace.
As a preferred technical scheme of the invention, in the step (II), the separation comprises the step of naturally layering the prefabricated material.
Preferably, after the natural stratification, the first mixture is located above the second mixture.
Preferably, the cooling means of the first mixture is water quenching.
Preferably, the cooling of the second mixture is air cooling.
In the invention, the separated first mixture is used for preparing a calcium magnesium phosphate phase, the separated second mixture is used for preparing a phosphorus-iron phase, and the density of the phosphorus-iron phase is greater than that of the calcium magnesium phosphate phase, so that the calcium magnesium phosphate phase is above the phosphorus-iron phase after natural layering, and after the two phases are completely layered, the first mixture and the second mixture are respectively taken out for post-treatment to prepare the calcium magnesium phosphate and the phosphorus-iron. The cooling method adopted by the first mixture is water quenching, and the cooling method adopted by the second mixture is air cooling, and the main reasons are that the first mixture needs a higher cooling speed to keep a glass state, phosphorus crystals are prevented from being separated out to maintain fertilizer efficiency, and the second mixture can be kept standing and cooled in air without the requirement on the cooling speed.
As a preferred embodiment of the present invention, in the step (iii), the post-treatment of the first mixture comprises: and sequentially crushing and screening the cooled first mixture to obtain the calcium magnesium phosphate fertilizer.
Preferably, the sieving of the first mixture is performed using a sieve.
Preferably, the mesh number of the screen is 80 meshes.
Preferably, the post-treatment of the second mixture comprises: and crushing the cooled second mixture to obtain blocky ferrophosphorus.
It should be noted that in the invention, the first mixture is sieved by using an 80-mesh sieve, and the obtained product meets the performance index requirement of the national standard GB/T20412-2006; the second mixture is crushed to form blocky ferrophosphorus, the mass of any blocky ferrophosphorus is not more than 30kg, the granularity is less than 20mm, and the requirement of the performance index of the ferrophosphorus industry standard YB/T5036-2012 is met.
As a preferred technical scheme of the invention, the method specifically comprises the following steps:
(1) mixing sludge and auxiliary materials, and then heating at 1000-1500 ℃ for 20-120 min to obtain a molten prefabricated material, wherein the mass percent of the sludge in the prefabricated material is 50-100%, and the prefabricated material contains effective P 2 O 5 The mass percent of the components is more than or equal to 12 percent, and the mol fraction ratio of each component in the prefabricated material is P 2 O 5 :SiO 2 :CaO:MgO＝1:1～5:2.5～10:1.5～5；
(2) Naturally layering the prefabricated material in the step (1) to obtain a first mixture and a second mixture, wherein the naturally layered first mixture is positioned above the second mixture, separating the two phases in a molten state, then performing water quenching cooling on the first mixture, and performing air cooling on the second mixture;
(3) and (3) sequentially crushing and screening the first mixture cooled in the step (2) to obtain the calcium magnesium phosphate fertilizer, and crushing the second mixture cooled into blocks to obtain blocky ferrophosphorus.
In a second aspect, the present invention provides a phosphorus-containing product obtained by the method of the first aspect, wherein the phosphorus-containing product comprises a calcium magnesium phosphate fertilizer and ferrophosphorus.
As a preferable technical scheme of the invention, the calcium magnesium phosphate fertilizer contains effective P 2 O 5 The mass percent of the P is more than or equal to 12 percent, and the mass percent of the P contained in the ferrophosphorus is more than or equal to 15 percent.
In the present invention providesThe calcium magnesium phosphate fertilizer meets the performance index requirements of the national standard GB/T20412-2006, and has effective P 2 O 5 The mass percentage of the phosphorus-iron complex is more than or equal to 12 percent, the byproduct ferrophosphorus meets the performance index requirement of the ferrophosphorus industry standard YB/T5036-2012, and the P content is more than or equal to 15 percent.
Compared with the prior art, the invention has the beneficial effects that:
according to the method for preparing the calcium magnesium phosphate fertilizer and co-producing the ferro-phosphorus and the phosphorus-containing product prepared by the method, few byproducts are generated in the preparation process, and the sludge is completely converted into the final product, so that the reduction, the stabilization and the harmlessness of the sludge are fully realized; in addition, the invention recovers elements such as phosphorus, silicon, calcium, magnesium and the like in the sludge to prepare the calcium magnesium phosphate fertilizer, and the phosphorus recovery rate is more than 90 percent; meanwhile, a large amount of iron in the sludge is converted into high-value ferrophosphorus, so that the economic benefit of the process is obviously improved, and the method has good social benefit and economic benefit. The preparation process provided by the invention is simple in flow, easy to construct and produce in large scale and has good industrial application prospect.
Drawings
FIG. 1 is a flow chart of a method for preparing a calcium-magnesia phosphate fertilizer and co-producing ferrophosphorus provided by embodiment 1 of the present invention.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
Example 1
The embodiment provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus, which comprises the steps of taking municipal sludge as a main raw material, preparing the calcium magnesium phosphate fertilizer and the ferrophosphorus in a blast furnace, and detecting to obtain components of the municipal sludge, wherein the carbon content in the municipal sludge is 23%, the ash content in the municipal sludge is 60%, the inorganic composition of the ash is shown in table 1 (weight percent wt%), the auxiliary material contains elements such as calcium and magnesium, the content of each component in the auxiliary material is detected, and the adding proportion of the auxiliary material is obtained through calculation.
As shown in fig. 1, the method comprises the following steps:
(1) mixing 25 parts of municipal sludge, 6.9 parts of calcium oxide and 1.5 parts of magnesium oxideMixing, heating at 1400 deg.C for 30min to obtain molten preformed material containing phosphorus (P) as ash base 2 O 5 Is 12.12 percent, and the mol fraction ratio of each component in the prefabricated material is P 2 O 5 :SiO 2 :CaO:MgO＝1:3.5:7:2.1；
(2) Naturally layering the prefabricated material in the step (1) to obtain a first mixture and a second mixture, wherein the naturally layered first mixture is positioned above the second mixture, separating the two phases in a molten state, then quickly pouring the first mixture into water for water quenching, and cooling the second mixture in air;
(3) and (3) crushing the first mixture cooled in the step (2), then screening by using an 80-mesh screen to obtain a calcium magnesium phosphate fertilizer, and crushing the second mixture cooled to obtain blocky ferrophosphorus.
The performance indexes of the calcium-magnesia phosphate fertilizer prepared by the embodiment are shown in table 2, and the performance indexes of ferrophosphorus are shown in table 3.
Example 2
The embodiment provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus, which comprises the steps of preparing the calcium magnesium phosphate fertilizer and the ferrophosphorus in a blast furnace by taking municipal sludge as a main raw material, adding a phosphorus-containing auxiliary material on the basis of adding an auxiliary material containing calcium and magnesium elements, detecting the content of each component in the auxiliary material, and calculating to obtain the adding proportion of the auxiliary material.
The method comprises the following steps:
(1) mixing 25 parts of municipal sludge, 4 parts of calcium oxide, 1.5 parts of magnesium oxide and 2 parts of calcium phosphate, and then heating at 1400 ℃ for 30min to obtain a molten prefabricated material, wherein the phosphorus content in the prefabricated material is calculated by ash base, and P is P 2 O 5 Is 18.71 percent, and the mol fraction ratio of each component in the prefabricated material is P 2 O 5 :SiO 2 :CaO:MgO＝1:2.65:6:2；
(2) Naturally layering the prefabricated material in the step (1) to obtain a first mixture and a second mixture, wherein the naturally layered first mixture is positioned above the second mixture, separating the two phases in a molten state, then quickly pouring the first mixture into water for water quenching, and cooling the second mixture in air;
(3) and (3) crushing the first mixture cooled in the step (2), then screening by using an 80-mesh screen to obtain a calcium magnesium phosphate fertilizer, and crushing the second mixture cooled to obtain blocky ferrophosphorus.
The performance indexes of the calcium-magnesia phosphate fertilizer prepared by the embodiment are shown in Table 4, and the performance indexes of ferrophosphorus are shown in Table 5.
Example 3
The embodiment provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus, which is different from the embodiment 1 in that no auxiliary materials are added in the step (1), and the rest of the operating conditions and the process parameters are completely the same as those in the embodiment 1.
The performance indexes of the calcium-magnesia phosphate fertilizer prepared by the embodiment are shown in table 2, and the performance indexes of ferrophosphorus are shown in table 3.
Example 4
The embodiment provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferro-phosphorus, which comprises the steps of taking peat as a main raw material, preparing the calcium magnesium phosphate fertilizer and ferro-phosphorus in an electric furnace, wherein auxiliary materials contain calcium, magnesium and other elements, detecting the content of each component in the auxiliary materials, and obtaining the adding proportion of the auxiliary materials through calculation.
The method comprises the following steps:
(1) mixing 25 parts of municipal sludge, 6.9 parts of calcium oxide and 1.5 parts of magnesium oxide, and then heating at 1000 ℃ for 20min to obtain a molten prefabricated material, wherein the phosphorus content in the prefabricated material is calculated according to ash base, and P is P 2 O 5 Is 13 percent by mass, and the mol fraction ratio of each component in the prefabricated material is P 2 O 5 :SiO 2 :CaO:MgO＝1:4:9:4.5；
(2) Naturally layering the prefabricated material in the step (1) to obtain a first mixture and a second mixture, wherein the naturally layered first mixture is positioned above the second mixture, separating the two phases in a molten state, then quickly pouring the first mixture into water for water quenching, and cooling the second mixture in air;
(3) and (3) crushing the first mixture cooled in the step (2), then screening by using an 80-mesh screen to obtain a calcium magnesium phosphate fertilizer, and crushing the second mixture cooled to obtain blocky ferrophosphorus.
Example 5
The embodiment provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus, which comprises the steps of taking sludge gasification slag as a main raw material, preparing the calcium magnesium phosphate fertilizer and the ferrophosphorus in a plasma furnace, adding a phosphorus-containing auxiliary material on the basis of adding an auxiliary material containing calcium and magnesium elements, detecting the content of each component in the auxiliary material, and calculating to obtain the adding proportion of the auxiliary material.
The method comprises the following steps:
(1) mixing 25 parts of municipal sludge, 3.5 parts of calcium oxide, 2 parts of magnesium oxide and 3 parts of calcium phosphate, and then heating at 1200 ℃ for 80min to obtain a molten prefabricated material, wherein the phosphorus content in the prefabricated material is calculated on ash basis, and P is 2 O 5 Is 15.37 percent, and the molar fraction ratio of each component in the prefabricated material is P 2 O 5 :SiO 2 :CaO:MgO＝1:4:6:4；
(2) Naturally layering the prefabricated material in the step (1) to obtain a first mixture and a second mixture, wherein the naturally layered first mixture is positioned above the second mixture, separating the two phases in a molten state, then quickly pouring the first mixture into water for water quenching, and cooling the second mixture in air;
(3) and (3) crushing the first mixture cooled in the step (2), then screening by using an 80-mesh screen to obtain a calcium magnesium phosphate fertilizer, and crushing the second mixture cooled to obtain blocky ferrophosphorus.
Example 6
The embodiment provides a method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus, which comprises the steps of preparing the calcium magnesium phosphate fertilizer and the ferrophosphorus in a blast furnace by taking municipal sludge as a main raw material, adding a phosphorus-containing auxiliary material on the basis of adding an auxiliary material containing calcium and magnesium elements, detecting the content of each component in the auxiliary material, and calculating to obtain the adding proportion of the auxiliary material.
The method comprises the following steps:
(1) mixing 25 parts of municipal sludge, 4.5 parts of calcium oxide, 1.5 parts of magnesium oxide and 3 parts of calcium phosphate, and then heating at 1500 ℃ for 120min to obtain a molten prefabricated material, wherein the phosphorus content in the prefabricated material is calculated according to ash base, and P is calculated 2 O 5 Is 17.93 percent, and the mol fraction ratio of each component in the prefabricated material is P 2 O 5 :SiO 2 :CaO:MgO＝1:5:10:5；
(2) Naturally layering the prefabricated material in the step (1) to obtain a first mixture and a second mixture, wherein the naturally layered first mixture is positioned above the second mixture, separating two phases in a molten state, quickly pouring the first mixture into water for water quenching, and cooling the second mixture in air;
(3) and (3) crushing the first mixture cooled in the step (2), then screening by using a 80-mesh screen to obtain the calcium magnesium phosphate fertilizer, and crushing the second mixture cooled to obtain blocky ferrophosphorus.
TABLE 1
| Composition (I) | SiO 2 | Al 2 O 3 | P 2 O 5 | Fe 2 O 3 | CaO | MgO |
| Content (%) | 27.91 | 19.11 | 18.85 | 20.41 | 6.34 | 1.41 |
TABLE 2
TABLE 3
TABLE 4
TABLE 5
The calcium magnesium phosphate fertilizer and the ferro-phosphorus prepared in the embodiments 1-3 of the invention both reach the national standard, the sludge is completely converted into the final product, the reduction, stabilization and harmlessness of the sludge are realized, and the phosphorus recovery rate is more than 90%. The mass of the prepared massive ferrophosphorus is not more than 30kg, the granularity is less than 20mm, and the requirement of performance index of the ferrophosphorus industry standard YB/T5036-2012 is met. From example 1, exampleAs shown in example 4 and Table 2, the contents of each component in the calcium-magnesium phosphate fertilizer prepared in example 1 were higher than the national standard, and the phosphorus dissolution rate (P dissolved in 2% citric acid) 2 O 5 Content, and P in the ore before dissolution 2 O 5 The content ratio, expressed in percentage) reaches more than 99 percent, while the calcium magnesium phosphate fertilizer and the ferro-phosphorus prepared in the example 4 can not reach the national standard, which is mainly because the auxiliary materials are added into the sludge in the example 1, the calcium magnesium phosphate fertilizer has the function of improving the effective phosphorus content and the citrate dissolution rate in the calcium magnesium phosphate fertilizer product. As can be seen from examples 1 and 2, the calcium-magnesia phosphate fertilizer of example 2 has an effective P content 2 O 5 The content and the phosphorus citrate dissolution rate are higher than those of the calcium magnesium phosphate fertilizer prepared in the embodiment 1, and the main reason is that in the embodiment 2, on the basis of adding auxiliary materials containing calcium and magnesium elements, auxiliary materials containing phosphorus are added to obtain higher-grade calcium magnesium phosphate fertilizer and ferrophosphorus so as to improve the added value of products.
In addition, the method recovers phosphorus, silicon, calcium, magnesium and other elements in the sludge to prepare the calcium magnesium phosphate fertilizer, has a phosphorus recovery rate of over 90 percent, converts a large amount of iron in the sludge into high-value ferrophosphorus, obviously improves the economic benefit of the process, and has good social benefit and economic benefit.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.
Claims (25)
1. A method for preparing a calcium magnesium phosphate fertilizer and co-producing ferrophosphorus is characterized by comprising the following steps:
heating sludge to obtain a molten prefabricated material;
(II) separating the prefabricated material in the step (I) to obtain a first mixture and a second mixture, and respectively cooling the first mixture and the second mixture;
(III) respectively carrying out post-treatment on the first mixture and the second mixture cooled in the step (II) to obtain a calcium magnesium phosphate fertilizer and ferrophosphorus;
in the step (I), auxiliary materials are added into the sludge, wherein the auxiliary materials comprise any one or combination of at least two of calcium, magnesium or phosphorus;
in the step (I), the sludge comprises phosphorus, silicon, calcium, magnesium and iron;
in the step (II), the cooling mode of the first mixture is water quenching, and the cooling mode of the second mixture is air cooling.
2. The method of claim 1, wherein in step (i), the sludge comprises any one of or a combination of at least two of municipal sludge, sludge coal, sludge gasification slag, or sludge ash.
3. The method of claim 2, wherein a reducing agent is added to the preformed material when the sludge is sludge ash.
4. The method of claim 3, wherein the reductant is coke.
5. The method of claim 3, wherein the mass of the reducing agent is 5% to 20% of the mass of the sludge.
6. The method of claim 1, wherein the adjunct comprises any one of serpentine, dolomite or olivine or a combination of at least two thereof.
7. The method according to claim 1, characterized in that the auxiliary material comprises phosphate ore and/or phosphate tailings.
8. The method of claim 1, wherein the auxiliary material comprises any one of or a combination of at least two of boric sludge, chromium slag, or carbide slag.
9. The method of claim 1, wherein the auxiliary material comprises any one of animal bone meal, livestock manure, or phosphorus-containing mushroom dregs, or a combination of at least two of them.
10. The method according to claim 1, wherein in step (I), the molar fraction ratio of phosphorus, silicon, calcium and magnesium elements in the preformed material is P 2 O 5 :SiO 2 :CaO:MgO=1:1~5:2.5~10:1.5~5。
11. The method according to claim 1, wherein the mass percentage of the sludge in the prefabricated material is 50-100%.
12. Method according to claim 1, characterized in that P is present in the prefabricated material 2 O 5 The mass percentage of the component (a) is more than or equal to 12 percent.
13. The method according to claim 1, wherein the heating temperature in step (I) is 1000 to 1500 ℃.
14. The method according to claim 1, wherein the heating time is 20-120 min.
15. The method of claim 1, wherein the heating is performed in a furnace.
16. The method of claim 15, wherein the furnace comprises any one of a blast furnace, a natural gas furnace, an electric furnace, or a plasma furnace.
17. The method of claim 1, wherein in step (ii), said separating comprises natural layering of the preformed material.
18. The method of claim 17, wherein the first mixture is located above the second mixture after the natural stratification.
19. The method of claim 1, wherein in step (iii), the post-treating of the first mixture comprises: and sequentially crushing and screening the cooled first mixture to obtain the calcium magnesium phosphate fertilizer.
20. The method of claim 19, wherein the screening of the first mixture is performed using a screen.
21. The method of claim 20, wherein the mesh size is 80 mesh.
22. The method of claim 1, wherein the post-processing of the second mixture comprises: and crushing the cooled second mixture to obtain blocky ferrophosphorus.
23. The method according to claim 1, characterized in that it comprises in particular the steps of:
(1) mixing sludge and auxiliary materials, and then heating at 1000-1500 ℃ for 20-120 min to obtain a molten prefabricated material, wherein the mass percent of the sludge in the prefabricated material is 50-100%, and the prefabricated material contains effective P 2 O 5 The mass percent of the components is more than or equal to 12 percent, and the mol fraction ratio of each component in the prefabricated material is P 2 O 5 :SiO 2 :CaO:MgO=1:1~5:2.5~10:1.5~5；
(2) Naturally layering the prefabricated material in the step (1) to obtain a first mixture and a second mixture, wherein the naturally layered first mixture is positioned above the second mixture, separating the two phases in a molten state, then performing water quenching cooling on the first mixture, and performing air cooling on the second mixture;
(3) and (3) sequentially crushing and screening the first mixture cooled in the step (2) to obtain a calcium magnesium phosphate fertilizer, and crushing the second mixture cooled to obtain blocky ferrophosphorus.
24. A phosphorus-containing product made by the method of any one of claims 1-23, wherein the phosphorus-containing product comprises a calcium magnesium phosphate fertilizer and a ferrophosphorus.
25. The phosphorus-containing product of claim 24, wherein the calcium magnesium phosphate fertilizer contains an effective amount of P 2 O 5 The mass percent of the P is more than or equal to 12 percent, and the mass percent of the P contained in the ferrophosphorus is more than or equal to 15 percent.
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| CH265853A (en) * | 1947-03-28 | 1949-12-31 | Wargons Ab | Process for the production of a phosphate fertilizer and fertilizer produced by this process. |
| US6921520B2 (en) * | 2002-10-07 | 2005-07-26 | James C. Barber And Associates Inc. | Process for upgrading raw phosphate ore |
| JP5984572B2 (en) * | 2011-08-10 | 2016-09-06 | 太平洋セメント株式会社 | Phosphate fertilizer and method for producing the same |
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