Soil conditioner prepared from ardealite and mercury slag synergistically and preparation method of soil conditioner

Abstract

The invention relates to the technical field of solid waste resource utilization, in particular to a soil conditioner synergistically prepared from ardealite and mercury slag and a method thereof.The ardealite and the mercury slag serve as raw materials and are smashed and sieved respectively to obtain powder with the appropriate particle size, then the ardealite powder and the mercury slag powder are matched according to the appropriate mass ratio, and the soil conditioner is prepared. Chemical elements in mercury residues and chemical elements in ardealite supplement nutrient elements mutually under the blending effect, the nutritional requirements of plant growth are met when soil is conditioned, heavy metal elements are promoted to be stably solidified through pH adjustment-aging process treatment in combination with proportion and process condition control, and the soil quality is improved. The leaching rate of heavy metal elements in the soil conditioner is reduced, the requirement of HG / T 4219-2011 is met, application of the mercury residues in the field of soil conditioners is achieved, consumption of ardealite is increased, harmless treatment of the mercury residues is achieved, and the treatment cost of the ardealite is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource utilization, and in particular to a soil conditioner prepared by synergistically preparing phosphogypsum and mercury slag and a method thereof. Background Art

[0002] Phosphogypsum is an acidic solid waste produced by the wet phosphoric acid process. At present, phosphogypsum is widely used in the preparation of fertilizers, soil conditioners, soil improvers and other products. For example: Patent application number 202110434000.2 discloses that phosphogypsum treated with active microorganisms is used as a carrier, and modified activated carbon and adsorbent are added to formulate a soil improver, which makes full use of the plant nutrients such as phosphorus, calcium, sulfur, and silicon contained in phosphogypsum, improves soil repair capacity, and improves the treatment effect of heavy metals. For another example: Patent application number 202111294235.2 discloses that phosphogypsum is ground with water and filtered to prepare a filtrate, a crystallizer and a modifier are added and stirred, the mixture is filtered statically, the filtrate is returned to the grinding, and the solid is dried into a soil conditioner to achieve the purpose of passivating heavy metals in the soil and reduce the risk of heavy metal re-migration. Another example: Patent application number 202111294239.0 discloses grinding phosphogypsum to expose fluorine, phosphorus, etc., adding dry chicken manure, and sealing and fermenting, so that after being used in the soil, it can reduce soil salinity, lower pH, and promote normal growth of crops. Another example: Patent application number 202110707985.1 discloses the use of alkali white mud, desulfurization gypsum, phosphogypsum, potassium ore, additives and water, through material mixing, drying, roasting, cooling, and crushing steps to prepare an active mineral soil conditioner intermediate; then add potassium humate, zinc sulfate, iron sulfate, sodium selenite and borax auxiliary materials, and add water to stir together, and granulate, dry and package the mixture to prepare a mineral soil conditioner.

[0003] As can be seen, a large number of existing technical solutions have been developed for the application of phosphogypsum in fields such as soil conditioners and soil improvers. However, these solutions still fail to meet the current demand for the disposal of phosphogypsum stockpiles. As a result, the wet-process phosphoric acid industry is still constrained by the disposal of solid wastes such as phosphogypsum, resulting in high costs. Therefore, the search for comprehensive phosphogypsum utilization technologies remains a hot topic for those skilled in the art.

[0004] Mercury smelting slag, also known as mercury slag, is an alkaline solid waste produced during the high-temperature smelting process. The slag obtained after high-temperature smelting contains low levels of heavy metals such as mercury, chromium, and arsenic. It also contains calcium, magnesium, silicon, aluminum, iron, and sulfur, making its use in soil improvement a non-recommended practice.

[0005] Since both phosphogypsum and mercury slag are industrial by-product solid waste, phosphogypsum is acidic and mercury slag is alkaline, mixing the two can achieve acid-base neutralization and element complementarity, so that the calcium element in the mercury slag can be solidified and retained. However, both phosphogypsum and mercury slag contain heavy metal elements. When phosphogypsum and mercury slag are mixed, if the preparation or treatment method is inappropriate, it will lead to a high mobility of heavy metals, making the application safety lower. Summary of the Invention

[0006] Based on the above technical problems, the present invention creates a soil conditioner by targeting the synergistic effect of mercury slag and phosphogypsum. The phosphogypsum and mercury slag are properly treated and mixed, and then properly proportioned and controlled under specific process conditions to obtain a soil conditioner prepared in a synergistic manner with phosphogypsum and mercury slag and a method thereof.

[0007] The specific technical solutions are:

[0008] One of the purposes of the present invention is to provide a method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag, comprising the following steps:

[0009] (1) crushing and sieving phosphogypsum to obtain phosphogypsum powder; crushing and sieving mercury ore smelting slag to obtain mercury slag powder;

[0010] (2) mixing phosphogypsum powder and mercury slag powder in a mass ratio of 10:0.1-25 to obtain a mixture;

[0011] (3) The mixture is adjusted to a pH of 5-6.5 using industrial sulfuric acid or waste sulfuric acid, aged for at least 24 hours, and granulated.

[0012] Phosphogypsum and mercury slag are used as raw materials, and powders of suitable particle size are obtained by crushing and sieving them separately. The phosphogypsum powder and the mercury slag powder are then mixed in an appropriate mass ratio. The chemical elements in the mercury slag and the chemical elements in the phosphogypsum are used to supplement each other's nutritional elements under the mixing effect, so that the nutritional needs of plant growth are met during soil conditioning. In addition, during the pH adjustment-aging process, combined with the control of the proportion and process conditions, the heavy metal elements are stably solidified, the leaching rate of the heavy metal elements in the soil conditioner is reduced, and the requirements of HG / T 4219-2011 are met. The application of mercury slag in the field of soil conditioners is realized, the disposal of phosphogypsum is increased, the harmless treatment of mercury slag is achieved, and the cost of phosphogypsum treatment is reduced.

[0013] In order to ensure the enhanced blending effect and improve the synergistic effect of the blending of mercury slag and phosphogypsum, preferably, in step (1), the crushing and screening is performed through an 80-100 mesh sieve.

[0014] Preferably, the aging treatment time is 24-72 hours. More preferably, the aging treatment time is 48 hours.

[0015] In order to enhance the soil conditioning effect, preferably, the granulation is to form particles with a particle size between 2-5 mm.

[0016] In order to reduce the As leachable rate in the soil conditioner and improve the overall heavy metal solidification effect of the soil conditioner, it is more preferred that in step (2), the phosphogypsum powder and the mercury slag powder are mixed in a mass ratio of 10:5-25.

[0017] In order to ensure that the soil conditioner has an excellent overall heavy metal solidification effect and significantly reduce the leachable rate of heavy metals such as Cd, Cr, and Hg, preferably, in step (2), the phosphogypsum powder and the mercury slag powder are mixed at a mass ratio of 10:5-10. More preferably, in step (2), the phosphogypsum powder and the mercury slag powder are mixed at a mass ratio of 10:5.

[0018] In order to ensure that the overall heavy metal solidification effect of the soil conditioner is excellent and to reduce the leaching rate of heavy metals such as As and Hg in the soil conditioner, preferably, in step (2), the phosphogypsum powder and the mercury slag powder are mixed in a mass ratio of 10:6.5 or 10:8.

[0019] The second purpose of the present invention is to provide a soil conditioner prepared by the above method.

[0020] Compared with the prior art, the technical effects created by the present invention are embodied in:

[0021] The invention utilizes mercury slag and phosphogypsum as raw materials, controls the particle size and mass ratio appropriately, and combines pH adjustment and aging treatment processes to promote the synergistic effect of mercury slag and phosphogypsum, thereby improving the soil conditioning effect, helping to promote crop growth and increase yield.

[0022] The soil conditioner obtained by the present invention has a low heavy metal content and can solidify free acid radicals in phosphogypsum, improving its soil conditioning effect. At the same time, it transforms solid wastes such as phosphogypsum and mercury slag into valuable resources, increasing the disposal of phosphogypsum, enabling the application of mercury slag in the field of soil conditioners, and reducing the environmental pressure caused by solid waste storage. The present invention uses phosphogypsum and mercury slag as raw materials to prepare the soil conditioner. Phosphogypsum contains free acid radicals such as sulfate and phosphate, which can combine with some heavy metal elements in the mercury slag to form insoluble salts, helping to enhance the heavy metal solidification effect. Furthermore, the free sulfate and phosphate ions can react with calcium ions to form insoluble compounds such as calcium phosphate and calcium sulfate. During the formation of these insoluble compounds, they can encapsulate heavy metal elements and achieve the purpose of solidifying heavy metals. As a result, after mercury slag and phosphogypsum are mixed to prepare the soil conditioner, the heavy metal content is significantly reduced, meeting the requirements of HG / T 4219-2011.

[0023] The invention directly utilizes the blending process followed by pH adjustment and aging process, and has a simple process flow and is easy to be promoted and implemented industrially. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to facilitate those skilled in the art to fully understand the technical solution of the present invention, the following description is made of the provided drawings in combination with the content of the technical solution and the provided drawings.

[0025] Figure 1 Create a process flow chart for this invention.

[0026] Figure 2 This is a growth diagram of pepper seedlings after the soil conditioner obtained in Example 1 of the present invention is mixed into pepper soil.

[0027] Figure 3 This is a test report for the soil conditioner obtained in Example 1 of the present invention for third-party testing. DETAILED DESCRIPTION

[0028] In order to facilitate those skilled in the art to correctly understand the present invention and enable those skilled in the art to fully understand the technical content of the present invention, the technical solution of the present invention is further explained below in conjunction with specific implementation methods, but this explanation does not limit the scope of protection required for the present invention. The scope of protection of the present invention by those skilled in the art cannot be limited to the following explanations. Any equivalent replacement or change made by any those skilled in the art or persons familiar with the technology in this field, on the basis of the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0029] like Figure 1 As shown, in certain embodiments, a method for preparing a soil conditioner by cooperating with phosphogypsum and mercury slag comprises the following steps:

[0030] (1) crushing the phosphogypsum through an 80-100 mesh sieve, for example, an 80 mesh, 90 mesh, or 100 mesh sieve to obtain phosphogypsum powder; crushing the mercury smelting slag through an 80-100 mesh sieve, for example, an 80 mesh, 90 mesh, or 100 mesh sieve to obtain mercury slag powder;

[0031] (2) mixing phosphogypsum powder and mercury slag powder in a mass ratio of 10:0.1-25, for example, 10:0.1, 10:5, 10:6.5, 10:8, 10:10, 10:20, 10:25, etc., to obtain a mixture;

[0032] (3) The mixture is adjusted to a pH value between 5 and 6.5 using industrial sulfuric acid or waste sulfuric acid, and aged for at least 24 hours, for example, 24 hours, 28 hours, 30 hours, 36 hours, 40 hours, 48 hours, 50 hours, 60 hours, 66 hours, 72 hours, 80 hours, etc., and granulated into particles with a particle size between 2 and 5 mm.

[0033] In order to better verify the technical effects of the present invention, the research team of the present invention carried out the following experimental research.

[0034] Phosphogypsum comes from a wet-process phosphoric acid production enterprise in Guizhou Province. Its physical and chemical properties are shown in Table 1 below:

[0035] Table 1

[0036]

[0037] The mercury slag comes from a mercury smelting enterprise. Its main components are shown in Table 2 below, and the leaching toxicity of heavy metals Cr, Hg, and As is shown in Table 3 below.

[0038] Table 2

[0039]

[0040] Table 3

[0041]

[0042] Example 1

[0043] The phosphogypsum is crushed and passed through an 80-mesh sieve to obtain phosphogypsum powder; the mercury smelting slag is crushed and passed through an 80-mesh sieve to obtain mercury slag powder; the phosphogypsum powder and the mercury slag powder are uniformly mixed in a mass ratio of 10:5 to obtain a mixture, and then the pH value is adjusted to between 5 and 6.5 using industrial waste acid (waste sulfuric acid generated by sulfuric acid production), aged for 24 hours, and granulated into particles with a particle size between 2 and 5 mm.

[0044] Example 2

[0045] The phosphogypsum is crushed and passed through a 100-mesh sieve to obtain phosphogypsum powder; the mercury smelting slag is crushed and passed through a 100-mesh sieve to obtain mercury slag powder; the phosphogypsum powder and the mercury slag powder are uniformly mixed in a mass ratio of 10:6.5 to obtain a mixture, and then industrial waste acid (waste sulfuric acid generated by sulfuric acid production) is used to adjust the pH value to between 5 and 6.5, and the mixture is aged for 72 hours and granulated into particles with a particle size between 2 and 5 mm.

[0046] Example 3

[0047] The phosphogypsum is crushed and passed through a 90-mesh sieve to obtain phosphogypsum powder; the mercury smelting slag is crushed and passed through a 90-mesh sieve to obtain mercury slag powder; the phosphogypsum powder and the mercury slag powder are uniformly mixed in a mass ratio of 10:8 to obtain a mixture, and then the pH value is adjusted to between 5 and 6.5 using industrial waste acid (waste sulfuric acid generated by sulfuric acid production), and the mixture is aged for 48 hours and granulated into particles with a particle size between 2 and 5 mm.

[0048] Example 4

[0049] The phosphogypsum is crushed and passed through an 80-mesh sieve to obtain phosphogypsum powder; the mercury smelting slag is crushed and passed through a 100-mesh sieve to obtain mercury slag powder; the phosphogypsum powder and the mercury slag powder are uniformly mixed in a mass ratio of 10:10 to obtain a mixture, and then the pH value is adjusted to between 5 and 6.5 using industrial waste acid (waste sulfuric acid generated by sulfuric acid production), and the mixture is aged for 36 hours and granulated into particles with a particle size between 2 and 5 mm.

[0050] Example 5

[0051] On the basis of Example 1, the rest are the same as Example 1, and the phosphogypsum powder and the mercury slag powder are uniformly mixed in a mass ratio of 10:15 to obtain a mixture.

[0052] Example 6

[0053] On the basis of Example 1, the rest are the same as Example 1, and the phosphogypsum powder and the mercury slag powder are uniformly mixed in a mass ratio of 10:25 to obtain a mixture.

[0054] Example 7

[0055] On the basis of Example 1, other aspects are the same as Example 1, and phosphogypsum powder and mercury slag powder are uniformly mixed in a mass ratio of 10:1 to obtain a mixture.

[0056] Example 8

[0057] On the basis of Example 1, the rest are the same as Example 1, and the phosphogypsum powder and the mercury slag powder are uniformly mixed in a mass ratio of 10:0.5 to obtain a mixture.

[0058] Example 9

[0059] On the basis of Example 1, other aspects are the same as Example 1, and an equal amount of phosphogypsum is used to replace the mercury slag.

[0060] Example 10

[0061] On the basis of Example 1, other aspects are the same as Example 1, and an equal amount of humus soil is used to replace the mercury slag.

[0062] The element content detection data of each embodiment is shown in Table 4.

[0063] Table 4

[0064]

[0065] Note:

[0066] ① The data in Example 1 is provided by third-party testing;

[0067] ② The data of Examples 2 to 10 were tested in the laboratory by the research team, and each group was tested three times to take the average value.

[0068] From Table 1 to Table 4 and Figure 3 It can be seen that different treatment processes and parameter controls will have different degrees of impact on the solidification effect of heavy metals such as As, Cd, Cr, Hg, and Pb in the soil conditioner; Examples 1 to 4 can all reduce the heavy metal leachable rate in the soil conditioner and improve the safety of the soil conditioner, but as the amount of mercury slag relative to phosphogypsum gradually increases, the solidification effect of heavy metals such as Cd, Cr, and Hg will deteriorate. Therefore, controlling the mixing ratio of phosphogypsum to mercury slag within an appropriate range will help to improve the overall leachable rate of heavy metals in the soil conditioner; at the same time, when the amount of mercury slag added is not zero, as the amount of mercury slag decreases, the overall heavy metal solidification effect of the soil conditioner will be unsatisfactory.

[0069] Based on the above experiments, the research team of the present invention mixed the soil conditioner obtained in Example 1 into the soil and then potted peppers. The pepper seedlings obtained were as follows: Figure 2 As shown, the pepper seedlings are tall and strong, and grow evenly.

[0070] Other matters not covered by the present invention may be achieved by conventional technical means with reference to the prior art or common knowledge known to those skilled in the art.

Claims

1. A method for preparing a soil conditioner by synergistically using phosphogypsum and mercury slag, characterized in that: The following steps are involved: (1) crushing and sieving phosphogypsum to obtain phosphogypsum powder; crushing and sieving mercury ore smelting slag to obtain mercury slag powder; (2) mixing phosphogypsum powder and mercury slag powder in a mass ratio of 10:0.1-25 to obtain a mixture; (3) The mixture is adjusted to a pH of 5-6.5 using industrial sulfuric acid or waste sulfuric acid, aged for at least 24 hours, and granulated.

2. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1, wherein: In the step (1), the crushing and screening is performed through an 80-100 mesh sieve.

3. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1, wherein: The aging treatment time is 24-72h.

4. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1 or 3, characterized in that: The aging time is 48 hours.

5. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1, wherein: The granulation is to form particles with a particle size between 2 and 5 mm.

6. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1, wherein: In the step (2), phosphogypsum powder and mercury slag powder are mixed in a mass ratio of 10:5-25.

7. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1 or 6, characterized in that: In the step (2), phosphogypsum powder and mercury slag powder are mixed in a mass ratio of 10:5-10.

8. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1 or 6, characterized in that: In the step (2), phosphogypsum powder and mercury slag powder are mixed in a mass ratio of 10:

5.

9. The method for preparing a soil conditioner by synergistically combining phosphogypsum and mercury slag according to claim 1 or 6, characterized in that: In the step (2), phosphogypsum powder and mercury slag powder are mixed in a mass ratio of 10:6.5 or 10:

8.

10. A soil conditioner prepared according to the method of any one of claims 1 to 9.

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