A method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste, and materials, applications, and restoration methods

Abstract

The present invention discloses a method and material, application and restoration method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste, which belongs to the technical field of ecological environment restoration. The preparation method is: mixing coal gasification slag, red mud and soil, aging, granulating, and roasting at 1050-1150°C to obtain desertification ecological environment restoration materials. The present invention fully utilizes the moisture contained in red mud through precise matching, and then fully utilizes the residual carbon contained in the coal gasification slag through reasonable granulation and scientific roasting to preheat and prepare porous desertification ecological environment restoration materials. While realizing the resource utilization and harmlessness of solid waste, it reduces energy consumption. The application of the product can also delay the evaporation of desert water and suppress the source of sand and dust.

Description

Technical Field

[0001] The present invention belongs to the technical field of ecological environment restoration, and relates to a method for restoring a desertified ecological environment, and in particular to a method for preparing a desertified ecological environment restoration material from coal gasification slag / red mud-based solid waste, and to materials, applications, and restoration methods. Background Art

[0002] In recent years, with the continuous development of the economy and society, water resource consumption has increased greatly, especially in the western region where water resources are already scarce, and it is facing an extremely serious desertification problem. At present, the main methods used for desertification control include vegetation restoration, laying grass grids, mechanical sand barriers, etc. These methods require a lot of manpower, material resources, and financial resources, so they are mainly used only along roads and railways. If mesh sand barriers are used, there is still the problem of environmental pollution under the influence of wind erosion and exposure. It is difficult to promote and apply on a large scale in Xinjiang, Gansu and other regions where water resources are extremely scarce and the land is vast and sparsely populated.

[0003] In recent years, industries such as coal-to-gas, coal-to-oil, and coal-to-hydrogen, which use coal gasification as the core technology, have been vigorously developed, and the amount of coal gasification slag produced has also increased significantly. Due to the high content of residual carbon in coal gasification slag and the inability of gasification slag to meet the requirements of raw materials such as construction materials for loss on ignition, it is mostly limited in its application in building materials. At the same time, due to the structural characteristics of carbon and ash melting, coating, adhesion, and high water content, there are serious constraints between the components during the mixing and other high-value utilization of circulating fluidized beds. Therefore, the current resource utilization of gasification slag is not high, and it is still mainly based on stockpiling and landfilling. The toxic and harmful trace elements, phenols, cyanides, etc. contained in it seriously threaten the local ecological environment. Therefore, the resource utilization and high-value utilization of coal gasification slag is a major issue that affects the healthy development of the coal chemical industry and enterprises.

[0004] Red mud is a typical solid waste produced by the alumina industry. With the continuous development of the alumina industry, the emission of red mud has increased year by year. At present, the problems of low dosage, low product performance and low added value in the process of red mud resource utilization have seriously restricted its large-scale utilization. At the same time, red mud contains 3% to 14% alkali metal oxides, most of which are weakly bound alkalis and semi-free alkalis. Red mud also contains a certain amount of heavy metal elements such as Cr, Ni, As, and Cu. Therefore, large-scale storage of red mud will lead to environmental problems such as salinization of the surrounding soil and groundwater pollution. Therefore, the development of red mud utilization technology with high utilization rate, stable product performance and high added value is the key to solving the problem of red mud resource utilization.

[0005] At present, one of the directions for large-scale disposal of coal gasification slag and red mud is the preparation of building materials. However, due to the high residual carbon content, large ignition loss and poor adhesion of coal gasification slag, its large-scale use in building material manufacturing is very difficult. Red mud has become a world problem in the field of solid waste resource utilization due to its small particle size, strong water holding capacity and high alkalinity. At the same time, the current methods for desertification control require a lot of manpower, material and financial resources, and some even require a lot of water resources, which has brought great difficulties to the control of deserts in the arid areas of northwest my country. Summary of the invention

[0006] The present invention provides a method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste, as well as materials, applications and restoration methods, so as to overcome the defects of the prior art.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste: coal gasification slag, red mud and soil (silt clay or clay) are mixed, aged, granulated, and calcined at 1050-1150°C to obtain desertification ecological environment restoration materials.

[0009] To optimize the above technical solutions, the specific measures taken also include:

[0010] Further, the following steps are included:

[0011] Step 1, the coal gasification slag, red mud and soil are matched and mixed evenly; the mass range of each chemical component in the raw materials composed of the coal gasification slag, red mud and soil is: SiO2, 40-65%; Al2O3, 10-32%; Fe2O3, 6-12%; Na2O and K2O, 1.5-5%; CaO and MgO, 4-8%; wherein Na2O and K2O, CaO and MgO are fluxes; specifically, the chemical components and proportions in the coal gasification slag, red mud and soil are determined by XRF, and the raw materials are matched accordingly to meet the above ranges;

[0012] Step 2: drying and grinding;

[0013] Step 3: adding water to adjust the moisture content of the raw material to 20-25%, aging for 48-72 h, preferably 48 h;

[0014] Step 4: granulation;

[0015] Step five: drying and roasting.

[0016] Furthermore, in step 2, the drying method is: leaving the mixed raw materials to stand for 20 to 30 hours, preferably 24 hours, so that the excess water in the red mud is fully absorbed by the gasification slag and the soil, so that the water in the raw materials is evenly distributed, and then drying at 100 to 110 ° C, preferably 105 ° C to constant weight; after grinding, passing through a 100 mesh sieve.

[0017] Furthermore, in step 4, the diameter of the embryos obtained by granulation is 1 to 4 cm, preferably 2 cm.

[0018] Furthermore, in step five, the drying method is: drying at 100-110 °C for 5-8 h, preferably drying at 105 °C for 6 h; the roasting method is: preheating at 250-350 °C for 20-40 min, preferably preheating at 300 °C for 30 min, then heating at 5-15 °C / min, preferably 10 °C / min, and roasting at 1050-1150 °C for 20-40 min, preferably 30 min.

[0019] The present invention also provides a desertification ecological environment restoration material prepared by the above method.

[0020] The present invention also provides the application of the above-mentioned desertification ecological environment restoration material in desertification ecological environment restoration.

[0021] The present invention also provides a method for restoring a desertification ecological environment: the above-mentioned desertification ecological environment restoration material is evenly covered on the surface of the desert soil to be restored.

[0022] To optimize the above technical solutions, the specific measures taken also include:

[0023] Furthermore, the coverage rate of the desertification ecological environment restoration material is not less than 10%. The coverage rate can be greater than 100%, and greater than 100% means laying multiple layers.

[0024] Furthermore, before laying the desertification ecological environment restoration material, water or plant fiber dust suppressant is evenly sprayed on the surface of the desert soil to be restored; the concentration of the plant fiber dust suppressant is 2-6 wt%, and the spraying amount of water or plant fiber dust suppressant is 2.5-5 L / m 2 .

[0025] The beneficial effects of the present invention are as follows: the present invention fully utilizes the moisture contained in the red mud through precise matching, and then through reasonable granulation and scientific roasting, fully utilizes the residual carbon contained in the coal gasification slag to preheat and prepare porous desertification ecological environment restoration materials. The present invention realizes the resource and harmless utilization of coal gasification slag and red mud, and reduces the harm caused by large-scale storage of coal gasification slag to enterprises and the surrounding ecological environment. At the same time, the present invention fully utilizes the residual heat of the residual carbon in the coal gasification slag, reducing the energy consumption of traditional material preparation. More importantly, the present invention provides a method for desertification ecological environment restoration, which can effectively reduce wind erosion, delay water evaporation, and achieve the purpose of desertification control and restoration by laying desertification ecological environment restoration materials on the surface of desert soil. Specifically, the restoration material can block the direct effect of wind on the surface of desert soil, absorb wind momentum, reduce near-surface wind speed, and thus inhibit soil wind erosion and reduce sand transport rate. Moreover, this method can effectively increase the aerodynamic roughness of the surface, reduce the soil erosion modulus, reduce soil and water loss, avoid the formation of new sources of wind and sand, and play the role of soil and water conservation, wind and sand control, and maintaining the balance and stability of the regional ecosystem. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a graph of arsenic and chromium leaching concentrations of the embryos of Examples 1 to 3 and the desertification ecological environment restoration materials prepared in Examples 1 to 4;

[0027] Figure 2 It is a schematic diagram of the anti-wind erosion experimental device;

[0028] Figure 3 This is the distribution map of wind-sand flow structure of desertification ecological environment restoration materials under different coverage rates;

[0029] Figure 4 It is the distribution map of wind-sand flow structure of desertification ecological environment restoration materials under different wind speed erosion conditions;

[0030] Figure 5 It is a graph showing the change in moisture content of the desertification ecological environment restoration methods of Example 8 and Comparative Example 1, and Example 9 and Comparative Example 2. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Example 1

[0032] This embodiment provides a desertification ecological environment restoration material, and the preparation method includes the following steps:

[0033] Step 1: 50 wt% coal gasification slag, 30 wt% red mud and 20 wt% clay are mixed evenly, wherein the mass fraction of each chemical component is shown in Table 1.

[0034] Step 2: Let the mixed raw materials stand for 24 hours to allow the excess water in the red mud to be fully absorbed, and then dry them at 105°C for 6 hours to constant weight; then grind the raw materials thoroughly and pass them through a 100-mesh sieve.

[0035] Step 3: Adjust the moisture content of the raw material to 20-25% by adding water and age it for 48 hours.

[0036] Step 4: Granulate the pellets using a disc machine, with a pellet diameter of 2.2 cm.

[0037] Step 5: Dry the embryo at 105°C for 6 hours; then place it in a muffle furnace, preheat it to 300°C, maintain it for 30 minutes, increase the temperature at 10°C / min, and roast it at a temperature of 1100°C for 30 minutes; cool it to obtain the desertification ecological environment restoration material. Example 2

[0038] This embodiment provides a desertification ecological environment restoration material, and the preparation method includes the following steps:

[0039] Step 1: Evenly mix 50 wt% coal gasification slag, 30 wt% red mud and 20 wt% clay.

[0040] Step 2: Let the mixed raw materials stand for 24 hours to allow the excess water in the red mud to be fully absorbed, and then dry them at 105°C for 6 hours; then grind the raw materials thoroughly and pass them through a 100-mesh sieve.

[0041] Step 3: Adjust the moisture content of the raw material to 20-25% by adding water and age it for 48 hours.

[0042] Step 4: Granulate the pellets using a disc machine, with a pellet diameter of 2.2 cm.

[0043] Step 5: Dry the embryo at 105°C for 6 hours; then place it in a muffle furnace, preheat it to 300°C, maintain it for 30 minutes, increase the temperature at 10°C / min, and roast it at a temperature of 1150°C for 30 minutes; cool it to obtain the desertification ecological environment restoration material. Example 3

[0044] This embodiment provides a desertification ecological environment restoration material, and the preparation method includes the following steps:

[0045] Step 1: Evenly mix 50 wt% coal gasification slag, 30 wt% red mud and 20 wt% clay.

[0046] Step 2: Let the mixed raw materials stand for 24 hours to allow the excess water in the red mud to be fully absorbed, and then dry them at 105°C for 6 hours; then grind the raw materials thoroughly and pass them through a 100-mesh sieve.

[0047] Step 3: Adjust the moisture content of the raw material to 20-25% by adding water and age it for 48 hours.

[0048] Step 4: Granulate the pellets using a disc machine, with a pellet diameter of 2.2 cm.

[0049] Step 5: Dry the embryo at 105°C for 6 hours; then place it in a muffle furnace, preheat it to 300°C, maintain it for 30 minutes, increase the temperature at 10°C / min, and roast it at a temperature of 1080°C for 30 minutes; cool it to obtain the desertification ecological environment restoration material. Example 4

[0050] This embodiment provides a desertification ecological environment restoration material, and the preparation method includes the following steps:

[0051] Step 1: 55 wt% coal gasification slag, 20 wt% red mud and 25 wt% clay are mixed evenly, wherein the mass fraction of each chemical component is shown in Table 1.

[0052] Step 2: Let the mixed raw materials stand for 24 hours to allow the excess water in the red mud to be fully absorbed, and then dry them at 105°C for 6 hours; then grind the raw materials thoroughly and pass them through a 100-mesh sieve.

[0053] Step 3: Adjust the moisture content of the raw material to 20-25% by adding water and age it for 48 hours.

[0054] Step 4: Granulate the pellets using a disc machine, with a pellet diameter of 3.1 cm.

[0055] Step 5: Dry the embryo at 105°C for 6 hours; then place it in a muffle furnace, preheat it to 300°C, maintain it for 30 minutes, increase the temperature at 10°C / min, and roast it at a temperature of 1090°C for 30 minutes; cool it to obtain the desertification ecological environment restoration material.

[0056] Table 1 Mass fraction of each chemical component in the raw materials of Example 1 and Example 4 (%)

[0057]

[0058] The environmental risks of the embryos of Examples 1 to 3 and the desertification ecological environment restoration materials prepared in Examples 1 to 4 were evaluated by the following methods: (1) Weigh 100 g of the sample (particle size <3 mm) on a dry basis and place it in a 2 L sealed wide-mouth bottle, add water (GB / T 6682, Level 2) at a liquid-solid ratio of 10:1 (L / kg), cover the bottle cap tightly and fix it vertically on a horizontal oscillating device, set the oscillation frequency to 110 times / min, the amplitude to 40 mm, oscillate at 23°C for 8 h, remove the extraction bottle and let it stand for 16 h. (2) Install a 0.45 μm filter membrane on the pressure filter to filter the leachate and collect the leachate, which is stored at room temperature. (3) The determination of heavy metal content in materials shall refer to the “Determination of Mercury, Arsenic, Selenium, Bismuth and Antimony in Solid Waste by Microwave Digestion / Atomic Fluorescence Method” (HJ702-2014) and the “Determination of 22 Metal Elements in Solid Waste by Inductively Coupled Plasma Emission Spectrometry” (HJ 781-2016).

[0059] The results are as follows Figure 1 As shown in the figure, the leaching concentrations of arsenic and chromium are lower than the evaluation standard of Class III water in the Groundwater Quality Standard (GB / T 14848-2017), indicating that the desertification ecological environment restoration material prepared by the present invention has a low environmental risk and does not have the possibility of causing secondary pollution. At the same time, according to the changes in the leaching of arsenic and chromium before and after roasting, it can be seen that the desertification ecological environment restoration material of the present invention greatly reduces the leaching of pollutants in the raw materials. Example 5

[0060] This embodiment provides a method for restoring a desertified ecological environment: the desertified ecological environment restoration material prepared in Example 1 is evenly covered on a 40 cm*60 cm desert soil surface layer at a coverage rate of 10%. Example 6

[0061] This embodiment provides a method for restoring a desertified ecological environment: the desertified ecological environment restoration material prepared in Example 1 is evenly covered on a 40 cm*60 cm desert soil surface layer at a coverage rate of 30%. Example 7

[0062] This embodiment provides a method for restoring a desertified ecological environment: the desertified ecological environment restoration material prepared in Example 1 is evenly covered on a 40 cm*60 cm desert soil surface layer at a coverage rate of 50%.

[0063] The desertification ecological environment restoration methods of Examples 5 to 7 were subjected to wind erosion resistance experiments: the wind speed was 10.6 m / s, and a sand collector was set up at the end of the test area. The sand collector consists of a bracket, a rectangular sand collection port and 10 sand collection boxes, with a height of 20 cm. The standard cross-sectional area of ​​each sand collection port is 2 cm*2 cm, and it can collect wind and sand flows within a height range of 20 cm above the ground. The experimental device is as follows: Figure 2 At the same time, a wind and sand attack background value experiment was carried out: and a control group was set up to conduct an anti-wind erosion experiment on the desert soil surface without the desertification ecological environment restoration materials laid under the same conditions.

[0064] According to the experimental results of Examples 5 to 7 and their control groups, the wind and sand flow structure distribution diagrams of desertification ecological environment restoration materials under different coverage rates were drawn, such as Figure 3 As shown, the wind erosion inhibition efficiency is calculated (the wind erosion inhibition efficiency is the ratio of "the difference between the wind erosion amount of bare land and the wind erosion amount under different restoration material coverage" to "the wind erosion amount of bare land"). Figure 3 It can be seen that after laying the desertification ecological environment restoration material of the present invention, the sand transport volume at different heights has dropped significantly compared with the original ground. The wind erosion inhibition rates of plots with a laying coverage rate of 10%, 30%, and 50% are 47.86%, 58.87%, and 65.02%, respectively.

[0065] The desertification ecological environment restoration method of Example 6 was subjected to wind erosion resistance experiments at different wind speeds: specifically, wind erosion resistance experiments were conducted at wind speeds of 6.2 m / s, 4.3 m / s, and 12.1 m / s, respectively. At the same time, a wind sand invasion background value experiment without laying desertification ecological environment restoration materials was conducted at each wind speed as a control group. Based on the experimental results, a wind sand flow structure distribution map of the desertification ecological environment restoration material under different wind speed erosion conditions was drawn, as shown in FIG. Figure 4 As shown. Figure 4 It can be seen that under different wind speeds, the anti-wind erosion effect of 30% coverage is better. Although the sediment transport rate gradually increases with the increase of wind speed, compared with the original ground conditions without coverage, the anti-wind erosion effect of this method is still significant. Example 8

[0066] This embodiment provides a method for restoring a desertified ecological environment: 2.5 L and 5 L of tap water are used to spray evenly on a 1 m 2 After spraying, a layer of desertification ecological environment restoration materials with a coverage rate of 30% was evenly laid on the surface of the desert soil. The moisture content of the surface soil was measured by weight method on the 3rd and 30th days. The results are shown in Table 2 and Table 3. Figure 5 shown.

[0067] Comparative Example 1

[0068] This comparative example provides a method for restoring a desertified ecological environment: 2.5 L and 5 L of tap water are respectively sprayed evenly on a 1 m 2 The surface soil moisture content of the desert soil was measured by gravimetric method on the 3rd and 30th days after spraying. The results are shown in Table 2 and Figure 5 shown. Example 9

[0069] This embodiment provides a method for restoring a desertified ecological environment: 2.5 L and 5 L of a 4 wt% plant fiber dust suppressant (ZX, purchased from Langfang Juhui Energy Saving Technology Co., Ltd.) were used to evenly blast sand on a 1 m 2 On the desertified soil, a layer of desertification ecological environment restoration materials with a coverage rate of 30% was evenly laid immediately after spraying. The moisture content of the surface soil was measured by gravimetric method on the 3rd and 30th days after spraying. The results are shown in Table 2 and Table 3. Figure 5 shown.

[0070] Comparative Example 2

[0071] This comparative example provides a method for restoring a desertified ecological environment: 2.5 L and 5 L of a 4 wt% plant fiber dust suppressant are uniformly sandblasted at 1 m 2 On the desertified soil, the surface soil moisture content was measured by gravimetric method on the 3rd and 30th day after spraying. The results are shown in Table 2 and Figure 5 shown.

[0072] Table 2 Changes in moisture content of the desertification ecological environment restoration methods of Example 8 and Comparative Example 1, Example 9 and Comparative Example 2

[0073]

[0074] From Table 2 and Figure 5 It can be seen that whether it is used in combination with tap water or plant fiber dust suppressant, the surface soil moisture content 3 days and 30 days after the application of desertification ecological environment restoration materials is significantly higher than before use. The increase in moisture content helps to suppress surface sand and dust and promote the growth of drought-resistant plants, while the growth of drought-resistant plants can also play a role in preventing wind and fixing sand.

[0075] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. In addition, the reagents, materials and operating procedures used herein are reagents, materials and conventional procedures widely used in the corresponding fields.

[0076] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste, characterized in that: The following steps are involved: Step 1: The coal gasification slag, red mud and soil are matched and mixed evenly; the mass range of each chemical component in the raw materials composed of the coal gasification slag, red mud and soil is: SiO2, 40-65%; Al2O3, 10-32%; Fe2O3, 6-12%; Na2O and K2O, 1.5-5%; CaO and MgO, 4-8%; Step 2: drying and grinding; Step 3: Adjust the moisture content of the raw material to 20-25% and age it for 48-72 hours; Step 4: granulation; Step 5, drying; preheating at 250-350°C for 20-40 min, then heating at 5-15°C / min, and calcining at 1050-1150°C for 20-40 min to obtain desertification ecological environment restoration materials.

2. The method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste according to claim 1, characterized in that: In step 2, the drying method is: leaving the mixed raw materials to stand for 20-30 hours, and then drying at 100-110°C to constant weight; After grinding, pass through a 100-mesh sieve.

3. The method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste according to claim 1, characterized in that: In step 4, the diameter of the embryos obtained by granulation is 1 to 4 cm.

4. The method for preparing desertification ecological environment restoration materials from coal gasification slag / red mud-based solid waste according to claim 1, characterized in that: In step 5, the drying method is: drying at 100-110°C for 5-8 hours.

5. A desertification ecological environment restoration material prepared by the method according to any one of claims 1 to 4.

6. The desertification ecological environment restoration material as claimed in claim 5 is used in desertification ecological environment restoration.

7. A method for restoring a desertified ecological environment, characterized in that: The desertification ecological environment restoration material described in claim 5 is evenly covered on the surface of the desert soil to be restored.

8. The method for restoring a desertified ecological environment according to claim 7, characterized in that: The coverage rate of the desertification ecological environment restoration materials is not less than 10%.

9. The method for restoring a desertified ecological environment according to claim 7, characterized in that: Before laying the desertification ecological environment restoration material, evenly spray water or plant fiber dust suppressant on the surface of the desert soil to be restored; The concentration of plant fiber dust suppressant is 2~6 wt%, and the spraying amount of water or plant fiber dust suppressant is 2.5~5 L / m 2 .

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