Reclamation soil using iron ore tailings as soil moisture retention layer and construction method

Abstract

The present invention relates to a reclaimed soil with iron ore tailings as a soil moisture retention layer and a construction method, and relates to the field of soil reconstruction and soil improvement. A reclaimed soil with iron ore tailings as a soil moisture retention layer, the soil comprises from bottom to top: a. a large rock bedrock layer; b. a crushed stone subsoil layer; c. a red clay heart soil layer; d. an iron ore tailings moisture retention layer; e. a loess or brown soil topsoil layer. Iron ore beneficiation tailings are used as the main reconstruction material for the reclaimed soil moisture retention layer, which increases the soil layer thickness and improves the water retention and storage capacity of the reclaimed soil. At the same time, they can also consume a large amount of tailings sand produced by iron ore mining and beneficiation, saving a large amount of reclaimed soil resources, avoiding the economic losses and ecological environmental damage caused by land occupation and concentrated storage of tailings, and can obtain good economic, environmental and social benefits.

Description

Technical Field

[0001] The invention relates to a reclaimed soil using iron ore tailings as a soil moisture retention layer and a construction method, and relates to the field of soil reconstruction and soil improvement. Background Art

[0002] Large-scale iron ore mining has caused a large amount of iron ore tailings to pile up into mountains, which are difficult to dispose of. With the wind and water, they are carried into rivers and farmlands, polluting the environment. In addition, the stacking of iron ore tailings requires the construction of large-scale tailings ponds, which takes up land and costs money, and hurts corporate profits.

[0003] The technology of using iron ore tailings to reconstruct and reclaim soil and improve the soil of medium and low-yield fields is the most economical and convenient way to utilize iron ore tailings as agricultural resources. For some abandoned mining pits, it is necessary to reclaim them into arable land. In the case of scarce soil sources, iron ore tailings can be used to construct reclaimed soil, use iron ore tailings as a soil moisture retention layer and form a suitable soil structure, reclaim them into arable land, and plant crops. On the one hand, it can make full use of iron ore waste resources, and on the other hand, it can increase the area of ​​arable land and improve the quality of arable land. Summary of the invention

[0004] The purpose of the present invention is to provide a technology and method for constructing a soil moisture conservation layer using iron ore tailings, so as to solve the problems of shortage of soil sources for land reclamation in mining areas and large-scale storage of iron ore tailings.

[0005] A reclaimed soil with iron ore tailings as a soil moisture retention layer, the soil comprising from bottom to top:

[0006] a. Massive rock bedrock

[0007] b. Gravel subsoil layer

[0008] c. Red clay subsoil layer

[0009] d. Iron ore tailings moisture retention layer

[0010] e. Brown soil or loess topsoil layer.

[0011] Preferably, the thickness of each layer of the reclaimed soil is as follows:

[0012] Massive rock bedrock layer: 3-8m, depending on the ground elevation;

[0013] Thickness of gravel subsoil layer: 20-30cm;

[0014] Thickness of red clay subsoil layer: 20-30cm;

[0015] Thickness of the iron ore tailings moisture retention layer: 20-30cm;

[0016] Thickness of brown soil or loess topsoil layer: 20-50cm.

[0017] Preferably, the bulk rock bedrock layer consists of bulk rock.

[0018] Furthermore, the bulk rock bedrock layer originates from waste rock discharged from mining stripping.

[0019] In the reclaimed soil of the present invention, large rocks are discarded and piled up in the order of original strata in order to improve the ground elevation of the reclaimed site so that it is at the same level as other surrounding plots after reclamation.

[0020] Preferably, the crushed stone subsoil layer consists of crushed stone.

[0021] Furthermore, the crushed stones of the structural subsoil layer come from waste rocks generated during the mineral processing process.

[0022] Furthermore, the average diameter of the crushed stone is 4 to 6 cm, preferably 5 cm.

[0023] In the reclaimed soil of the present invention, after the accumulation of large rocks, crushed stones are spread over the soil and the cracks are filled and compacted to form a subsoil layer of the reconstructed soil, which is also a plastic fixing layer to prevent uneven leakage of the soil in the upper layer.

[0024] Preferably, the red clay constituting the subsoil layer comes from red clay excavated and piled up in mines.

[0025] In the reclaimed soil of the present invention, red clay is laid on the crushed stones and compacted to serve as the subsoil layer of the reconstructed soil body, in order to prevent water leakage and play a role in plastic fixation and water and fertilizer conservation.

[0026] Preferably, the iron ore tailings are derived from dry tailings discharged from iron ore beneficiation.

[0027] Furthermore, the iron ore tailings particle composition is: clay (<0.002mm) 0.23%, powder (0.05-0.002mm) 31.28%, sand (>0.05mm) 68.42%, and there is no sand or gravel larger than 2mm.

[0028] In the reclaimed soil of the present invention, iron ore tailings are spread under the cultivated soil layer to retain water. Spreading a large amount of tailings can reduce the amount of imported soil, and at the same time can consume a large amount of tailings, reducing the large amount of tailings stored and the land occupied and the pollution to the environment.

[0029] Preferably, the brown soil or loess originates from the brown soil or loess at the source location of the surface soil stripped by mining.

[0030] In the reclaimed soil of the present invention, the tailings are rolled and leveled and then covered with brown soil or loess from the source of the surface soil stripped by mining for crop planting.

[0031] Another object of the present invention is to provide a method for constructing the above-mentioned reclaimed soil using the iron ore tailings as the soil moisture retention layer.

[0032] A method for constructing reclaimed soil using iron ore tailings as a soil moisture retention layer comprises the following steps:

[0033] S1, pile up the large rocks in the original stratigraphic order so that they are at the same level as other surrounding plots after reclamation;

[0034] S2, after the accumulation of large rocks, crushed stones are spread over the cracks and compacted to form the subsoil layer of reconstructed soil;

[0035] S3, laying red clay on the gravel and filling the joints and compacting it as the subsoil layer of the reconstructed soil;

[0036] S4, covering the iron ore tailings above the subsoil layer and below the cultivated soil layer to form an iron ore tailings moisture conservation layer;

[0037] S5, after the iron ore tailings are flattened, brown soil or loess from the source of the surface soil stripped during mining is spread on top of it.

[0038] The beneficial effects of the present invention are as follows: iron ore beneficiation tailings serve as the main reconstruction material of the water-retaining layer of the reclaimed soil, which increases the thickness of the soil layer and improves the water-retaining and water-storage capacity of the reclaimed soil. At the same time, it can also consume a large amount of tailings sand produced by iron ore mining and dressing, saving a large amount of reclaimed soil resources, avoiding economic losses and ecological environmental damage caused by land occupation and concentrated storage of tailings, and can obtain good economic, environmental and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the soil reconstruction process for reclamation;

[0040] In the figure, the reference numbers are as follows: a bedrock layer, b subsoil layer, c heart soil layer, d moisture retention layer, e topsoil layer.

[0041] Figure 2 Different soil profile construction measures in the experimental plot

[0042] Figure 3 Effects of various structural measures (1) Bulk density (2) Field water holding capacity (3) Soil moisture content (4) Soil electrical conductivity (5) Plant height (6) Stem diameter (7) Corn yield DETAILED DESCRIPTION

[0043] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0044] The test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0045] One of the specific implementation plans:

[0046] On the site to be reclaimed in the mining area, iron ore tailings are used to construct the cultivated soil layer on the basis of abandoned rock and soil. First, large pieces of mining abandoned rocks are piled up to increase the ground elevation, and then crushed stones are spread and filled and compacted to form the subsoil layer of reconstructed soil to prevent uneven leakage of the upper soil; secondly, red clay is spread on the crushed stones and filled and compacted as the heart soil layer of the reconstructed soil body to retain water and fertilizer, and then iron ore tailings are spread to retain moisture. When the red clay source is scarce, a large amount of tailings can be directly spread as a moisture retention layer. Finally, the tailings are rolled and flattened and covered with brown soil or loess at the soil source for planting crops.

[0047] In the following embodiments, the iron ore tailings are derived from the dry-discharged tailings of iron ore beneficiation of Shengde Rixin Mining Co., Ltd., and its main components are as follows: the chemical components of the dry-discharged iron tailings (iron ore tailings) of iron ore beneficiation mainly include SiO2, CaCO3, A12O3, P2O5, Fe2O3, FeO, Na2O, MgO, Na2CO3, K2O, BaCO3 and H2O, etc., and the tailings also contain a variety of trace elements.

[0048] The iron ore tailings particle composition is: 0.23% of clay particles (<0.002mm), 31.28% of powder particles (0.05-0.002mm), 68.42% of sand particles (>0.05mm), and there is no sand particles and gravel larger than 2mm.

[0049] The crushed stone of the structural subsoil layer comes from waste rock produced during the mineral processing process, and has a diameter of about 5 cm.

[0050] The red clay of the structural subsoil layer comes from the red clay excavated and piled up in mines.

[0051] The brown soil or loess is derived from the brown soil or loess at the source of surface soil stripped by mining.

[0052] The large rock bedrock layer comes from waste rocks discharged from mining stripping and has a diameter of about 50 cm.

[0053] Example 1

[0054] S1, covering with large rock layers. On the land to be reclaimed, discarded large rocks are piled up in the order of the original strata to raise the ground elevation of the reclaimed site so that it is at the same level as other surrounding plots after reclamation.

[0055] S2, gravel layer. After the large rocks are piled up, gravel is spread and compacted to form the subsoil layer of the reconstructed soil, which is also a plastic fixing layer to prevent uneven leakage of the upper covered soil.

[0056] S3, covering with red clay layer. Red clay is laid on the gravel and compacted to serve as the subsoil layer for reconstructing the soil body, so as to prevent water leakage, play a role in plastic fixation, and retain water and fertilizer.

[0057] S4, covering the iron ore tailings layer. Covering the iron ore tailings under the cultivated soil layer can retain water. Covering a large amount of tailings can reduce the amount of imported soil, and at the same time can consume a large amount of tailings, reducing the large amount of tailings stored and the pollution to the environment.

[0058] S5, covering the arable soil. After the tailings are rolled and leveled, brown soil or loess from the surface soil source of mining is covered on top for crop planting. This step also combines the technology of improving medium and low-yield fields by mixing the surface of iron ore tailings. After applying 5cm of iron ore tailings on the soil surface, it is tilled and mixed to improve the heavy texture of the reclamation cover soil.

[0059] Field plot test

[0060] In 2020, an experimental plot was established on an abandoned river channel in Xincheng Village, Xiaotang Town, Jianping County, Chaoyang City, Liaoning Province, and a total of 10 comparative measures were constructed (Table 1). The effects of each construction measure were compared and analyzed ( Figure 3 ).

[0061] From the results of soil property comparison and analysis, it can be concluded that using iron ore tailings as a moisture-retaining layer in soil profile construction can effectively improve the field water holding capacity and soil moisture content of the constructed soil. Iron ore tailings can effectively store water and provide moisture to the topsoil when there is less rainfall in the region, making the moisture content of the constructed soil higher than that of local normal farmland soil, and will not cause crop salt damage. In the year of construction, the growth level of corn in the constructed soil was basically the same as that of local normal farmland, and the corn yield was equivalent to or even better than that of local normal farmland. The above fully illustrates that when iron ore tailings are used in large quantities for farmland soil profile construction in the semi-arid area of ​​western Liaoning, using a certain thickness of iron ore tailings instead of soil as a moisture-retaining layer is an effective and appropriate method to improve the moisture characteristics of reclaimed soil. In addition, the soil bulk density after tillage and mixing after applying 5 cm of iron ore tailings on the soil surface is significantly reduced, and the field water holding capacity and soil moisture content are better than the measures of not mixing iron ore tailings with the topsoil. In view of the heavy clay characteristics of the original topsoil in the semi-arid area of ​​western Liaoning, applying 5 cm iron ore tailings on the topsoil and fully mixing it can change the mechanical composition of the topsoil layer through the irregular sand particles of the iron ore tailings, thereby changing the soil porosity and effectively reducing the bulk density of the topsoil.

[0062] Table 1 Ten comparative measures in the experimental plot

[0063]

Claims

1. A reclaimed soil with iron ore tailings as soil moisture retention layer, characterized by: The soil includes from bottom to top: a. Massive rock bedrock layer, 3-8m thick, depending on the ground elevation; b. Gravel subsoil layer, thickness is 20-30cm; c. Red clay subsoil layer, thickness is 20-30cm; d. Iron ore tailings moisture retention layer, thickness is 20-30cm; e. Brown soil or loess topsoil layer, thickness is 20-50cm; The iron ore tailings particle composition is: 0.23% clay particles, whose particle size is less than 0.002mm, 31.28% powder particles, whose particle size is 0.05-0.002mm, 68.42% sand particles, whose particle size is greater than 0.05mm, and no sand particles and gravel larger than 2mm; The method for constructing reclaimed soil comprises the following steps: S1, pile up the large rocks in the original stratigraphic order so that they are at the same level as other surrounding plots after reclamation; S2, after the accumulation of large rocks, crushed stones are spread and compacted to form the subsoil layer of reconstructed soil; S3, laying red clay on the gravel and filling the joints and compacting it as the subsoil layer of the reconstructed soil; S4, covering the iron ore tailings above the subsoil layer and below the cultivated soil layer to form an iron ore tailings moisture conservation layer; S5, after the iron ore tailings are flattened, brown soil or loess from the source of the surface soil stripped during mining is spread on top of it.

2. The reclaimed soil with iron ore tailings as soil moisture retention layer according to claim 1, characterized in that: The bulk rock bedrock layer is composed of bulk rocks with an average diameter of 40 to 60 cm, and the bulk rock bedrock layer comes from waste rocks discharged from mining stripping.

3. The reclaimed soil with iron ore tailings as soil moisture retention layer according to claim 1, characterized in that: The crushed stone subsoil layer is composed of crushed stones with an average diameter of 4 to 6 cm. The crushed stones constituting the subsoil layer come from waste rocks generated during the mineral processing process.

4. The reclaimed soil with iron ore tailings as soil moisture retention layer according to claim 1, characterized in that: The red clay constituting the subsoil layer comes from the red clay excavated and piled up in mines.

5. The reclaimed soil with iron ore tailings as soil moisture retention layer according to claim 1, characterized in that: The brown soil or loess is derived from the brown soil or loess at the source of surface soil stripped by mining.

6. The reclaimed soil with iron ore tailings as soil moisture retention layer according to claim 1, characterized in that: The iron ore tailings are derived from dry tailings discharged from iron ore dressing.

7. The reclaimed soil with iron ore tailings as soil moisture retention layer according to claim 2, characterized in that: The large rocks have an average diameter of 50 cm.

8. The reclaimed soil with iron ore tailings as soil moisture retention layer according to claim 3, characterized in that: The average diameter of the crushed stones is 5 cm.

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