Medium-low grade phosphorite pretreatment method
Technical Field
The invention relates to the technical field of medium and low grade phosphorite treatment, in particular to a method for pretreating medium and low grade phosphorite.
Background
The important and difficult-to-regenerate resources of phosphorus ore lead the phosphorus element to be widely dispersed in the nature along with the development of the phosphorus element and the preparation of downstream products, and because the phosphorus element is newly accumulated into the phosphorus ore for hundreds of millions of years, in 2010, 5 countries, such as China, Germany, Japan, English and American, take the phosphorus ore as rare natural resources to protect.
The phosphorite existing in nature occupies most low-grade phosphorite, takes second grade phosphorite and least high-grade phosphorite. In the mining and treating process of medium-grade and low-grade phosphorite, the acidolysis treatment is a common treatment mode, and the medium-grade and low-grade phosphorite is rich in a large amount of associated elements, such as magnesium element, iron element, calcium element and the like, so that acidolysis solution after acidolysis can contain magnesium ions, calcium ions, iron ions and the like, and the ions exist, so that a large amount of precipitates can be generated in subsequent crystallization treatment, and the washing water for the precipitates can be increased.
At present, the amount of associated element ions in acidolysis solution is reducedGenerally, the medium-low grade phosphorite is pretreated by adopting a flotation process, the grade of the phosphorite is preliminarily improved, however, the content of impurities in the phosphorite is different and the compactness of tissues is different due to different mineral age, different burying positions and the like of the phosphorite, so that the difficulty of the flotation process is increased, and the pretreatment cost is increased; moreover, P in phosphorite obtained by flotation of phosphorite at present2O5The content of the concentrate reaches up to 25 percent, and the flotation pretreatment has high cost and poor applicability and the P in the concentrate2O5The content is only maintained in the region of medium-grade phosphorite, which is not beneficial to the subsequent phosphorite treatment.
Therefore, the method for treating the phosphorite has important significance for effectively improving the grade of the phosphorite and facilitating subsequent treatment of the phosphorite.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a pretreatment method of middle-low grade phosphorite, in the pretreatment method, acid liquor with different concentrations is added into the phosphorite in a gradient treatment mode, and the particle size and the reaction temperature of the phosphorite are controlled, so that the grade of the phosphorite is improved, and the subsequent treatment difficulty is reduced. The pretreatment method has the advantages of strong practicability and wide applicability, and P in phosphorite can be treated by the pretreatment method2O5The content is more than 30 percent, and the grade of the phosphorite is effectively improved.
The technical scheme of the invention is as follows:
a method for pretreating middle-low grade phosphorite comprises preparing raw materials and preparing acid liquor;
in the preparation of raw materials, the raw materials are crushed, and the particle size of the raw materials is controlled to be 0.8-3 mm;
preparing acid liquor A and acid liquor B in the acid liquor preparation process; the concentration of the acid liquid A is 30-35%, and the concentration of the acid liquid B is 40-45%;
the treatment process comprises the following steps:
(1) pulverizing the raw materials, mixing with water, and making into water slurry;
(2) adding the acid liquor A into the water slurry, reacting the acid liquor A with substances in the raw materials, and controlling the reaction temperature to be between 10 and 20 ℃ to obtain acid slurry A for later use;
(3) adding the acid liquor B into the acid pulp A, continuously reacting the acid liquor B with substances in the raw materials, and controlling the reaction temperature to be between 10 and 20 ℃ to obtain acid pulp B;
(4) filtering the physalis alkekengi B for the first time to obtain a solid phase A and a liquid phase A; carrying out secondary filtration on the liquid phase A to obtain a solid phase B and a liquid phase B; collecting the solid phase A and the solid phase B, namely the concentrate obtained after pretreatment, and P in the concentrate2O5The content of (B) is more than 30 percent.
Further, the raw material is carbonate type middle-low grade phosphorite.
Further, the nitric phosphate fertilizer is obtained by performing acidolysis, filtering and washing, elution crystallization and decalcification on concentrate obtained by pretreating raw materials.
Furthermore, in the acidolysis process of the concentrate, the concentration of nitric acid is 58 percent; controlling the acidolysis temperature between 60 and 65 ℃; by using the concentration and controlling the acidolysis temperature, the phosphorus in the concentrate can be dissolved in the acidolysis solution, and the yield of the phosphorus is improved.
Furthermore, in the filtering process, a plate and frame filter is adopted for filtering, and the particle size of the medium-grade and low-grade phosphorite is limited in the pretreatment process, so that the problem that the filter aid is required to be added in the filtering stage to improve the filtering effect in the prior art can be effectively avoided, the filtering efficiency is improved, and the production cost is reduced.
Furthermore, in the process of elution crystallization, ethanol is used as an elution agent, so that the method has the advantages of environmental protection and no pollution.
Further, an ammonium sulfate method is adopted in the decalcification process, and ammonium sulfate is added as a decalcification agent to generate phosphogypsum; due to the fact that F is subjected to pretreatment-Removing the organic substances in the solution during the filtration process to obtain the organic substances and F in the phosphogypsum-The content is low, so that the application range of the phosphogypsum can be improved.
Compared with the prior art, the invention has the beneficial effects that:
1. the quality of the phosphorite is improved by pretreating the medium-low grade phosphorite, and high-quality ore sources are directly provided for enterprises.
2. According to the pretreatment method provided by the invention, the nitric acid is used for pretreatment, and the pretreatment is the same as the acid used for subsequent concentrate treatment, so that excessive impurities are prevented from being doped in an acidolysis solution obtained in the concentrate treatment process, and the amount of the impurities in phosphogypsum is reduced; at the same time, after pretreatment, F in the obtained concentrate-The content is low, so that the F-content in the phosphogypsum is low, and the use limit of the phosphogypsum is reduced.
3. According to the pretreatment method provided by the invention, the particle size of the medium-grade and low-grade phosphorite is limited, so that the concentrate can be rapidly and efficiently filtered without adding a filter aid when being filtered after being subjected to acidolysis by 58% of nitric acid, and the filtering efficiency is improved.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A method for pretreating middle-low grade phosphorite comprises preparing raw materials and preparing acid liquor;
in the preparation of raw materials, the raw materials are crushed, and the particle size of the raw materials is controlled to be 0.8-3 mm;
preparing acid liquor A and acid liquor B in the acid liquor preparation process; the concentration of the acid liquid A is 32.5 percent, and the concentration of the acid liquid B is 45 percent;
the treatment process comprises the following steps:
(1) pulverizing the raw materials, mixing with water, and making into water slurry;
(2) adding the acid liquor A into the water slurry, reacting the acid liquor A with substances in the raw materials, and controlling the reaction temperature to be 15 ℃ to obtain acid slurry A for later use;
(3) adding the acid liquor B into the acid pulp A, continuously reacting the acid liquor B with substances in the raw materials, and controlling the reaction temperature to be 12 ℃ to obtain acid pulp B;
(4) filtering the physalis alkekengi B for the first time to obtain a solid phase A and a liquid phase A; carrying out secondary filtration on the liquid phase A to obtain a solid phase B and a liquid phase B; collecting a solid phase A and a solid phase B, namely the concentrate obtained after pretreatment;
when the raw material is medium-grade phosphorite, the raw material is pretreated by the method, the components of the concentrate obtained after the pretreatment are shown in table 1, and the components in the raw ore are also recorded in table 1.
TABLE 1 Effect of treating Medium grade phosphorus ore by the method of the present invention
|
P2O5 |
CaO
|
MgO
|
F- |
Crude ore (%)
|
26.35
|
49.63
|
3.52
|
3.17
|
Concentrate (%)
|
34.16
|
20.16
|
0.57
|
0.21 |
Example 2
A method for pretreating middle-low grade phosphorite comprises preparing raw materials and preparing acid liquor;
in the preparation of raw materials, the raw materials are crushed, and the particle size of the raw materials is controlled to be 0.8-3 mm;
preparing acid liquor A and acid liquor B in the acid liquor preparation process; the concentration of the acid liquor A is 30 percent, and the concentration of the acid liquor B is 43 percent;
the treatment process comprises the following steps:
(1) pulverizing the raw materials, mixing with water, and making into water slurry;
(2) adding the acid liquor A into the water slurry, reacting the acid liquor A with substances in the raw materials, and controlling the reaction temperature to be 20 ℃ to obtain acid slurry A for later use;
(3) adding the acid liquor B into the acid pulp A, continuously reacting the acid liquor B with substances in the raw materials, and controlling the reaction temperature to be 20 ℃ to obtain acid pulp B;
(4) filtering the physalis alkekengi B for the first time to obtain a solid phase A and a liquid phase A; carrying out secondary filtration on the liquid phase A to obtain a solid phase B and a liquid phase B; collecting a solid phase A and a solid phase B, namely the concentrate obtained after pretreatment;
when the raw material is low-grade phosphorite, the raw material is pretreated by the method, the components of the concentrate obtained after the pretreatment are shown in table 2, and the components in the raw ore are also recorded in table 2.
TABLE 2 Effect of treating Low grade phosphorus ore by the method of the present invention
|
P2O5 |
CaO
|
MgO
|
F- |
Crude ore (%)
|
22.04
|
54.65
|
4.17
|
3.64
|
Concentrate (%)
|
31.43
|
21.33
|
0.72
|
0.44 |
As can be seen from the combination of tables 1 and 2, after pretreatment, both low-grade phosphate ore and medium-grade phosphate ore can be treated to have higher grade, and P is used2O5The content is more than 30 percent; CaO, MgO and F-The content of the nitro-phosphate is reduced, the reduction of the impurity amount provides a good mineral source foundation for the subsequent production of the nitro-phosphate with high content, and the subsequent treatment process and the treatment difficulty are shortened.
Example 3
Carrying out acidolysis treatment on the concentrate obtained in the embodiment 1 by using 58% nitric acid, controlling the temperature to be 62 ℃ in the treatment process, stirring at a stirring speed of 300r/min in the acidolysis process to ensure that acidolysis is more thorough, filtering acidolysis solution after acidolysis by using a plate and frame filter, washing filter residues after filtering by using clear water for 3 times, and mixing the recovered washing water with the filtrate for subsequent treatment; the filtration rate was recorded and the composition of the residue was analyzed.
Comparative example 1
The difference from example 3 is that the particle size of the raw material (i.e. raw ore) is between 40-300 mesh.
Comparative example 2
The difference from example 3 is that the particle size of the raw material (i.e. raw ore) is between 40-300 mesh; during the filtering process of the acidolysis solution, humic acid as a filter aid is added.
Statistics were made on the filtration rate and the composition of P2O5 in the filter residue for example 3, comparative example 1 and comparative example 2, as shown in table 3.
TABLE 3 filtration Rate and composition statistics
|
P2O5(%)
|
Filtration Rate (m)3/m2.h)
|
Example 3
|
0.42
|
65.8
|
Comparative example 1
|
1.22
|
5.3
|
Comparative example 2
|
0.87
|
63.4 |
As can be seen from Table 3, the filtration rate of comparative example 1 was slow and the residue P remained in the filtration cake under the condition of small particle size2O5More; the filtration rate was significantly increased after the addition of the filter aid in comparative example 2, which is similar to that of example 3, indicating that in the present invention, the filtration rate was significantly increased by controlling the amount of the filter aid during the pretreatment processThe particle size of the raw material provides a good filtration foundation for the concentrate filtration process, and can be equivalent to the filtration rate of the filter aid without adding the filter aid, which shows that the pretreatment process provided by the invention has an indispensable effect in the production process of the nitrophosphate fertilizer.
Although the present invention has been described in detail by referring to the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.