Investigation Of Preparation And Performance Of Glass-ceramics From Gold Tailings

Gold tailing is the major waste residue which is produced in the process ofrefining gold from gold ores by flotation. Production of gold tailing is almostequal to originated gold ores owning to the low-grade gold ores ordinarily.Therefore, the great amount of gold tailing is generated in the process ofrefining gold from gold ores. A large quantity of gold tailings usually are simplydisposed in open dumps, the management procedure used currently for thetailings causes the serious pollution of environment and brings the great threatenfor peoples in the ore fields inevitably. Glass-ceramic are polycrystalline solidswith a residual glassy matrix which are produced by treatment basic glasseswith nucleating agent. The gold tailings containing a large amount of CaO, SiO2and Al2O3can be a good raw material for CaO-Al2O3-SiO2system ofglass-ceramic production. Thus the utilization of gold tailing for glass-ceramicsis an effective and environment-friendly way and a good approach for thesustainable development of gold mining. The transformation of gold tailingsinto glass-ceramics has great social and environmental benefits.In this paper CaO-Al2O3-SiO2system of glass-ceramics are prepared withgold tailings from hanyin as main raw materials, calcite, borax, ZnO, Cr2O3, andSb2O3as auxiliary materials by melting and sintering methods, respectively. Theinfluence of the content of gold tailings, heat treatment and sintering scheduleson glass-ceramics from gold tailings, respectively. The thermal properties,phases and microstructures of glass-ceramics from gold tailings werecharacterized by differential scanning calorimetry(DSC), X-ray diffraction andscanning electron microscopy(SEM), respectively. The bending strengths,thermal expanding coefficients and densities of the samples were measured byDLL-402C expansion tester, PT-1036PC compression tester and Archimedesmethod, respectively.The results:(1) The CaO-Al2O3-SiO2system of glass-ceramics from gold tailings in Hanyin as main raw materials and other required materials wereproduced by melting method and sintering method, respectively. The resultsshow that the content of gold tailings, calcites, borax, ZnO, Cr2O3, Na2SiF6andSb2O3were65%,25%,4.7%,1.7%,1.3%,1.3%and1.0%in optimal recipeof the glass-ceramics from gold tailings, respectively.(2) The main crystallinephases of glass-ceramics from gold tailings by melting method were augite,diopside (CaMgSi2O3) and diopside solid solution, the secondary crystallinephase were wollastonite and potassium iron silicate (KFeSi2O6). The maincrystalline phases of glass-ceramics from gold tailings by sintering method werediopside (CaMgSi2O3) and anorthite (CaAl2Si2O8). The research have shownthat the amount of diopside was increasing with the increase of sinteringtemperature. However, the amount of anorthite was decreasing when thesintering temperature was in range of850℃～1000℃.(3) The largercrystallinity and densification of glass-ceramics were achieved by treating glassspecimens with gold tailings of65%at nucleation temperature of820℃for2hfollowed by the crystallization temperature of950℃for3h. The optimalmicrostructure of glass-ceramics from gold tailings of65%were produced bysintering at temperature of950℃for3h.(4) The optimal properties ofglass-ceramics from gold tailings by melting method were prepared by treatingglass simples with gold tailings of65%at nucleation of820℃for2h followedby crystallization at950℃for3h, and the thermal expanding coefficients,bending strengths and densities of the glass-ceramics from gold tailings bymelting method were68.7×10-7/℃,122MPa,2.836g/cm3, respectively. Theoptimal properties of glass-ceramics from gold tailings were achieved bysintering glass simples with gold tailings of65%at950℃for3h, and thethermal expanding coefficients, bending strengths and densities of theglass-ceramics from gold tailings by sintering method were65.4×10-7/℃,166MPa and2.626g/cm3, respectively.