Method for repairing heavy metal-polluted soil by using red mud granular material

A technology for particulate materials and soil pollution, applied in sustainable waste treatment, solid waste management, climate sustainability, etc., can solve problems such as soil pH rise, soil pH rise rapidly, vegetation and soil microbial damage, etc., and achieve low cost. , high economic value, and the effect of solving heavy metal polluted soil

Inactive Publication Date: 2016-02-03
SUN YAT SEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The technical problem to be solved by the present invention is to overcome the problem that the existing direct use of red mud powder to repair polluted soil causes the soil pH to rise rapidly due to the rapid release of free alkali, which will cause harm to vegetation and soil microorganisms. A soil remediation method for stabilizing and solidifying heavy metal ions with granulated red mud, using the gelling properties of gypsum, Portland cement, and fly ash to prepare red mud granular soil remediation agents for stabilizing and solidifying heavy metal ions
The remediation method of the granular remediation agent is low in cost, can effectively solve the problem of rapid increase in soil pH, and realize in-situ remediation of farmland soil polluted by heavy metals

Method used

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  • Method for repairing heavy metal-polluted soil by using red mud granular material
  • Method for repairing heavy metal-polluted soil by using red mud granular material
  • Method for repairing heavy metal-polluted soil by using red mud granular material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] Embodiment 1 Remediation of red mud powder material to soil

[0050] 1. Analysis of the properties of red mud

[0051] (1) Image analysis of red mud

[0052] In this example, the waste red mud produced by the Bayer process of China Power Investment Shanxi Aluminum Co., Ltd. to produce alumina is used for research. The XRD pattern of the red mud is shown in the attached figure 1 As shown, the main minerals in red mud are calcite (CaCO 3 ), diaspore (AlO(OH)), calcium aluminosilicate (CaAl 2 o 2 Si 8 ), calcium silicate hydrate (Ca 3 Si 2 o 7 1.5H 2 O), hemimorphite (Zn 4 Si 2 o 7 ·H 2 O) etc. Among these substances, calcite and hemimorphite are diamond-shaped crystal planes, which are the main skeleton and can play a certain role in gelling; while diaspore and calcium silicate mainly play a role in filling and gelling in the skeleton. effect.

[0053] (2) Chemical composition of red mud

[0054] The chemical composition of red mud depends on the compositi...

Embodiment 2

[0072] Example 2 Research on gelation modification of red mud

[0073] The present invention selects Portland cement, gypsum, fly ash and other materials in order to improve the gelling ability of the red mud. After a lot of research and screening, we finally selected gypsum, cement and fly ash as the cementitious and modified materials.

[0074] 1. Gelation properties of raw materials

[0075] As described in Example 1, the red mud itself has a certain gelling performance, but it is weak and the initial setting time is relatively long. Further research on its gelling properties: the red mud was air-dried and crushed through a 60-mesh sieve, sealed and stored for later use. According to the gray water ratio of 1:2.5, the pH is 12.36. In order to measure the gelling property of red mud raw material and facilitate subsequent granulation experiments, the self-gelling time of each sample was tested with water-cement ratios of 0.5 and 0.6. See Table 4 for relevant data.

[007...

Embodiment 3

[0099] Example 3 The impact of cementitious materials compounding on the gelling performance of red mud

[0100] 1. The influence of cement and fly ash on the gelling properties of red mud

[0101] (1) As can be seen from the above research results, cement and fly ash have the most significant effect on improving the gelling performance of red mud. In order to further explore a better scheme for improving the gelling performance of red mud, the present invention also studies cement and fly ash The effect of compound combinations on the gelling performance of red mud.

[0102] (2) According to the same method, by adding 10% cement and fly ash in different ratios, study its influence on the gelling performance of red mud. The gel properties of samples with different ratios are shown in Table 9.

[0103] Table 9 Improvement of red mud gelling performance by cement and fly ash compound

[0104]

[0105]

[0106] From the comparison of Table 9, Table 3, and Table 4, it can...

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Abstract

The invention discloses a red mud granular material and an application thereof. A red mud particle soil repairing agent takes red mud powder, gypsum, cement and fly ash as main materials, phosphate is doped as an activation material, thereby, gelling capability of red the mud powder and capability for fixing heavy metal ions in a stable mode can be increased, a series of processes of mixing by adding water, balling, and drying solidification at normal temperature can be carried out, so that the spherical particle soil repairing agent can be obtained by composite moulding of the red mud raw ore powder material. The method realizes preparation of the red mud powder with granulation at normal temperature, the obtained red mud particle soil repairing agent has certain mechanical strength and good heavy metal stable solidification performance, the heavy metal-polluted soil or sludge can be effectively processed, OH radical ions can be slowly released simultaneously, a pH value of the soil after restoration by the repairing agent is basically stabilized below 7.5, problems of fast increase of the pH value of the soil and poor growth condition for plants during a soil restoration process by the red mud powder can be effectively overcome, and the method has high application value and environment benefit.

Description

technical field [0001] The invention belongs to the technical field of soil heavy metal pollution control. More specifically, it relates to a method for remediating heavy metal-contaminated soil, especially lead-contaminated soil, using red mud granular materials. Background technique [0002] The soil polluted by heavy metals in my country has reached 20 million hm 2 , accounting for 1 / 6 of the total arable land area, and the farmland polluted by industrial "three wastes" reached 7 million hm 2 , resulting in a reduction in grain production of 10 billion kg per year. At the same time, mining and smelting have also caused serious heavy metal pollution in the soil and other superficial environments of the mining area and surrounding areas. In the southwestern and central regions of my country, especially in Yunnan, Jiangxi, Hunan, Guizhou and Guangxi provinces and regions, due to mining and metal smelting, the land in the mining area and surrounding areas is seriously poll...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B28/04C04B18/30
CPCY02W30/91
Inventor 石太宏赵光利陈惠康徐源汤叶涛王新璋柴洪云程乾坤张红云黄雄飞
Owner SUN YAT SEN UNIV
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