Preparation of Mineral Polymer from Potassium Feldspar Wastes: An Experimental Study
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摘要: 以福建沙县田口钾长石尾矿粉体为主要原料, 以煅烧高岭石作配料, 硅酸钠作结构模板剂, 氢氧化钠作激活剂, 进行了制备矿物聚合材料的实验研究.实验样品静置固化7~ 2 8d, 其抗压强度高达19.4~ 2 4.9MPa, 耐酸性、耐碱性指标均优于相似建材的国家标准.在配料组成中, 控制高岭石用量为2 0 %, 适当提高硅酸钠的用量和固/液比, 有利于提高制品的力学性能.实验表明, 材料抗压强度随固化时间的延长而呈抛物线式发展.矿物聚合材料的形成过程为: 铝硅酸盐固体组分的溶解络合、分散迁移、浓缩聚合、脱水硬化.由铝硅酸盐凝胶相固化而成的基体相, 其化学组成与沸石相近, 微观结构极可能与蛋白石类似, 物理形态上呈三维网状结构, 将未溶解的晶质颗粒胶结为坚硬块体, 是矿物聚合材料获得良好力学性能的结构基础.Abstract: Potassium feldspar wastes from Shaxian County, Fujian Province were used as raw materials to prepare mineral polymer in this study. The waste particles ranging from 0.4 to 1 000 μm in size, averaging to 45 μm, were mixed with calcined kaolin. With liquid sodium silicate as structural template, and sodium hydroxide solution as activator, the mineral polymers were prepared. The optimal technical parameters were determined by the orthogonal experiments, as shown below (by weight) : the proportion of kaolin in the solid materials was 1/4, the ratio of NaOH solution (10 mol/L) to sodium silicate (m =3.3) in the liquid was 3/7, the ratio of the solid to liquid was 4, at 60 ℃ and for 72 h. Compressive strengths of the mineral polymer samples were tested up to 19.4-24.9 MPa after 7-28 d's solidification, the acid and alkaline resistances well satisfied the China National Specifications for analogues of structural construction materials. As shown in the experiments, the kaolin proportion in the solid materials was kept around 20%, but the compressive strengths of the mineral polymers were enhanced with increasing both the proportion of sodium silicate in the liquid and the ratio of solid to liquid, resulting in the paradoxical change of the compressive strengths with the prolonging of the solidifying time. The formation process of mineral polymers can be divided into four stages, i.e., dissolution of aluminium and silicon from particles of kaolin and the waste solid materials and its complex in the liquid, diffusion from the particle surface into interstitial space, concentrating and polymerization of the components by geochemical reactions to form interstitial aluminosilicate gel, and dehydration of extra water and solidification of the gel phase. The matrix phase so formed in mineral polymer, similar to zeolite in chemical composition, is possibly an analogue of opal in microtexture, and shows a three dimension network in physical framework acting as a structural foundation of the mineral polymers with excellent mechanical properties.
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Key words:
- mine solid waste /
- mineral polymer /
- aluminosilicate /
- geopolymerization.
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图 1 实验样品G336b微观结构的SEM照片
plg.斜长石; qtz.石英; mtx.基体相
Fig. 1. SEM photograph showing textural interfaces between crystal particles and matrix phase of sample G336b
图 2 拟合计算的材料抗压强度与实测强度的对比
Fig. 2. Comparison of compressive strengths with those determined by the expriments
图 3 优化工艺条件下材料抗压强度对配料组成和固化时间关系
Fig. 3. Correlation between compressive strengths and initial proportion of the components and solidifying time at the optimal technical condition
图 4 不同固化时间的样品的X射线粉末衍射
由下到上, 样品分别固化0, 3, 7, 14, 28 d
Fig. 4. XRD patterns for mineral polymers with different times of solidification
图 5 不同固化时间的样品的红外光谱吸收
由下到上, 样品分别固化3, 7, 14, 28 d
Fig. 5. Infrared spectra for mineral polymers with different times of solidification
表 1 钾长石尾矿的化学分析结果
Table 1. Chemical analysis of potassium feldspar mine waste
表 3 矿物聚合材料样品G336b的化学成分分析结果
Table 3. Chemical component analysis of the geopolymer, sample G336b
表 2 代表性矿物聚合材料样品的实验结果
Table 2. Experimental results of representative geopolymer specimens
表 4 材料强度随固化时间变化的实验结果
Table 4. Experiment results showing the variation of geopolymer's strength with solidifying time
表 5 样品G672b耐酸碱性的实验结果
Table 5. Experimental results of chemical stabilities of sample G672b in 5%HCl and 1 mol/L NaOH solutions
表 6 钾长石尾矿滤液中Si和Al的含量
Table 6. Leached Si and Al concentrations of the mine waste in 10 mol/L NaOH and KOH solutions
表 7 材料抗压强度对配料组成和固化时间的回归分析结果
Table 7. Regression coefficients of compressive strength as a function of component molar fractions and solidifying time
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