| Vanadium is an important strategic resource. Vanadium alloy steel is widely used in national defense, electronics, machinery, railway, automobile, ship, household appliance and construction and other fields. The main raw materials for vanadium are stone coal, vanadium slag and vanadium solid waste. The main way of extracting V2O5 is from stone coal. Currently, in Gui zhou province, there are two methods to extract V2O5. Vanadium mine enterprises to adopt the technology mainly are calcium vanadium roasting process and the wet process acid leaching of vanadium. In the current technical conditions, it is valued to excavate when vanadium grade reach 0.8%. 1t V2O5 produces 200 t vanadium slag. But traditional disposal methods are mainly based on the tailings storage. Some associated heavy metal elements in long-term weathering leaching, may release and migration to the periphery of the soil, surface water, on the local environmental pollution. Vanadium slag heap takes up a lot of land, much capital, explore the way of resource utilization of vanadium slag is very necessary. In this research, the main use of calcium roasting vanadium slag and wet acid leaching of vanadium slag are studied, of which using calcium roasting vanadium slag takes roasting calcium vanadium slag as the main raw material, combined with expanded perlite, sodium silicate, borax and other light-weight materials prepared by thermal wall insulation materials and as cement admixture; besides, the use of calcium roasting vanadium slag and wet acid leaching of vanadium slag is to wet acid leaching of vanadium slag as cement admixture materials explore more ways of vanadium slag utilization to reduce environmental pollution caused by vanadium slag.The results show:1) Vanadium slag with the features of high silicon, high aluminum, low calcium, has a content of SiO2 and Al2O3 accounting up to 85% and it belongs to the high-alumina slag. It can be used as raw material to prepare Light-weight wall insulation materials.2) Research on the firing light-weight wall insulation materials tests, firing out of the material showed smooth and pore distribution-intensive, In addition,the materials had low thermal conductivity and the main mineral phase were calcium feldspar, quartz, mullite. the material compressive strength >6MPa, bulk density <0.9g/cm3, the thermal conductivity of <0.25W/(m·K), water absorption <16%. The obtained material meets the performance requirements of a lightweight material.3) According to XRD and SEM analysis of the light wall insulation materials known, mineral mainly composed of calcium feldspar, quartz, mullite, there are many pores on the section, and these pores is not a single existence, but blending with each other by a number of different pore aperture, indicating that there is crystalline phase formed.4) The experimental results showed that taking the acid leaching picking-up vanadium slag with a content of 25% and the calcified roast picking-up vanadium slag with a content of 35% as active cement admixture can meet the requirements for composite Portland cement in the Standard of Common Portland Cement(GB175-2007) and the 32.5 cement strength grade; when the acid leaching picking-up vanadium slag content ≤10% or 10%≤ the calcified roast picking-up vanadium slag content ≤30%, the cement samples could meet the requirements for the 32.5R cement strength grade, when the calcified roast picking-up vanadium slag content ≤10%, used as active cement admixture the strength of the cement samples could meet the requirements for the 52.5 cement strength grade. In addition, the cement hydration products are mainly ettringite and calcium silicate hydrate. The experimental results showed that the residue could be used as active cement admixture.5) According to the cement phase and microstructural analysis, the hydration products of cement specimens mainly calcium aluminate, calcium silicate hydrate and ettringite, as well as needle-like and rod-like hydrates C-S-H gel particles, that make cement present good flexural, compressive properties, showing that calcium roasting vanadium slag and wet acid leaching of vanadium slag can be used as cement admixture. |
PDF Full Text Request