尾矿的资源化利用

论文总字数：26998字

摘 要

矿产资源是人类发展不可或缺的资源，在开采矿产资源的过程中，由于选矿技术和生产设备等原因的影响，往往会产生许多选矿剩余的尾矿，这些尾矿往往富含许多重金属离子，如果不能得到有效地利用，不仅会造成矿产资源地浪费，甚至会导致造成环境地污染。

目前国内的有许多尾矿利用的研究已经成熟，但大部分研究的是尾矿中的粗砂等成分，尾矿中的细砂及含量比较少的黏土成分还没有成熟的技术将其有效地进行利用。聚丙烯酸钠是一种对重金属离子具有强吸附性的高分子材料，本文主要探究将聚丙烯酸钠（PAAS）运用在尾矿的的细砂以及少量黏土的处理上，并将其用作填埋场衬垫（CCL）的可能性。

根据现行的《生活垃圾卫生填埋场防渗系统工程技术规范》[1]，CCL的渗透系数须小于1×cm/s。由于垃圾填埋场的衬垫需要承受一定的上覆压力，需要一定的抗压强度,有学者认为，衬里土料的无侧限抗压强度最小值为200kPa。经过聚丙烯酸钠处理后的尾矿土，在防止其对环境造成二次污染的前提下，将其运用到垃圾填埋场的衬垫，不仅可以降低成本，还能变废为宝，对改善环境具有很大的意义[2]。

本文将重点探究加入PAAS对一定级配的黏性土的最优含水率的影响，以及加入聚丙烯酸钠对粉土的渗透系数以及抗压强度的影响，填埋场的底部温度和干湿状况时常会发生变化。通过干湿冻融循环试验探究其对加入聚丙烯酸钠的试样和不加入聚丙烯酸钠的试样的抗压强度的影响，从而探究加入聚丙烯酸钠对试样在干湿交替的环境中和在温度变化较大的环境中的耐久性的影响，最后通过离子吸附试验，探究在饱和状态下加入聚丙烯酸钠前后的黏土对重金属离子的吸附能力的变化，并得出以下结论：

掺入PAAS使黏性土的最优含水率和最大干密度均下降；当掺入聚丙烯酸钠含量为5%时，其渗透系数会下降至原来的百分之一，试验测得的改良土试样的渗透系数在3.0×cm/s左右，符合作为垃圾填埋场衬垫渗透系数的要求。通过PAAS改良的土样的水稳性较好，在干湿循环环境中其强度会稍微下降，但是仍符合垃圾填埋场衬垫的强度要求，但在冻融循环环境中PAAS对改良土的强度影响较大，在冻融循环次数达到6次时其强度会接近0，但未掺入PAAS的土样强度未发生明显变化。掺入PAAS对普通黏性土的强度影响不大，且能大幅度增强其对金属离子的吸附能力。

关键词：尾矿，聚丙烯酸钠，重金属离子，压实黏土衬垫，抗压强度

ABSTRACT

Mineral resources are indispensable resources for human development. In the process of mining mineral resources, due to the influence of beneficiation technology and production equipment, there are often many tailings left over from beneficiation. These tailings are often full of many heavy metal ions. And we should prevent it from polluting the environment.

At present, there are many domestic tailings utilization research has been mature. However, most of the studies are on the coarse sand and other components in tailings. Fine sand and clay with less content in tailings have not yet been effectively utilized by mature technology. This paper mainly explores the possibility of applying PAAS to the treatment of fine sand from tailings and a small amount of clay, and to the liner of refuse landfill.

Researches at home and abroad generally believe that as the liner of landfill, its permeability coefficient should be less than 1×cm/s. Because the liner of landfill needs to bear certain overburden pressure, it needs certain compressive strength. The tailings treated with sodium polyacrylate can not only reduce the cost, but also turn waste into treasure, which is of great significance to improve the environment, on the premise of preventing secondary pollution to the environment.

This paper will focus on the effect of adding sodium polyacrylate (PAAS) on the optimal moisture content of clay with certain gradation, and the effect of adding sodium polyacrylate on the permeability coefficient and compressive strength of silt. The bottom temperature and dry-wet condition of landfill often change. We will investigate the compressive strength of the samples with and without sodium polyacrylate through the dry-wet freeze-thaw cycle test, so as to explore the effect of adding sodium polyacrylate on the durability of the samples in dry-wet alternating environment and in the environment with large temperature changes. Finally, through ion adsorption test, the change of adsorption capacity of clay to heavy metal ions before and after adding sodium polyacrylate in saturated state was explored, and a conclusion was drawn.

When the content of sodium polyacrylate is 5%, the permeability coefficient of the clayey soil decreases to 1% of the original. The hydraulic conductivity of the improved soil which adds PAAS measured by the test is about 3.0× cm/s, which meets the requirement of the permeability coefficient of the landfill liner. The soil sample improved by PAAS has good water stability, and its strength will decrease slightly in the dry-wet cycling environment, but it still meets the strength requirements of landfill liner.. When the number of freeze-thaw cycles reaches 6 times, the strength of the soil sample without PAAS will approach 0. The addition of PAAS has little effect on the strength of common clay and can greatly enhance its adsorption capacity for metal ions.

KEY WORDS: tailings, sodium polyacrylate, heavy metal ions, compacted clay liner, compressive strength.

目 录

摘要 I

Abstract II

第一章 绪论 2

1.1 尾矿及其分类 2

1.2 聚丙烯酸钠简介 2

1.3 国内尾矿利用现状及利用途径 3

1.2.1 国内尾矿利用现状 3

1.2.2 尾矿的利用途径 3

1.3 尾矿利用研究进展 4

1.3.1 国内相关研究进展 4

1.3.2 国外相关研究进展 5

1.4 本文主要的研究目的和技术路线 6

1.4.1 研究目的 6

1.4.2 工作安排和技术路线 6

第二章 试验材料和方法 8

2.1 试验材料 8

2.1.1 聚丙烯酸钠（PAAS）及其物理性质 8

2.1.2 尾矿土 8

2.2 试验方法 9

2.2.1 微观试验XRD、SEM 9

2.2.2 击实试验的原理和方法 9

2.2.3 渗透试验的原理和方法 12

2.2.4 干湿冻融循环的基本原理和方法 14

2.2.5 无侧限抗压强度试验的原理和方法 15

2.2.6 离子吸附试验的原理和方法 16

第三章 试验结果及分析 17

3.1 微观试验XRD、SEM结果分析 17

3.2 击实试验曲线及分析 19

3.2.1 普通黏性土的击实曲线 19

3.2.2 PAAS改良土的击实曲线 19

3.2.3 改良土的击实曲线结果分析 20

3.3 渗透试验结果及分析 21

3.3.1 渗透系数曲线和结果分析 21

3.3.2 PAAS对渗透系数的影响分析 22

3.3.3 围压对改良土渗透系数的影响分析 22

3.4 干湿冻融循环结果及分析 23

3.4.1 干湿循环试验结果及分析 23

3.4.2 冻融循环试验结果及分析 25

3.5 无侧限抗压强度试验结果及分析 26

3.6 离子吸附试验结果及分析 28

第四章 结论与展望 29

4.1 PAAS改良土作为CCL的可行性研究结论 29

4.2 试验中存在的不足之处 29

4.3 研究展望 30

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