氧化铁浸染型石英中性正浮选制备低铁石英砂

Preparation of low iron quartz by neutral direct flotation from iron oxide disseminated quartz

氧化铁含量是决定石英在不同领域应用的主要因素,尤其是氧化铁浸染型石英砂,因氧化铁的赋存状态、共伴生、浸染程度及粒度差异,常规擦洗、强磁选及酸法反浮选难以有效降低石英中三氧化二铁含量。中性条件下,以抑制剂抑制含铁矿物、采用捕收剂使充分解离的石英上浮,通过粗选、精选进一步降低石英精砂中三氧化二铁含量。研究表明:自然pH下,采用淀粉基抑制剂CTSS、两性捕收剂兼起泡剂ZD-3联合作用,可将此类石英砂三氧化二铁含量由130～150mg/kg降至60～100mg/kg,满足超白光伏玻璃用硅质原料的质量要求;入浮砂粒度上限为0.6mm,以≤0.5mm为宜;对含铁铝硅酸盐矿物、氧化铁浸染型石英砂,中性正浮选石英精砂三氧化二铁含量低于酸性反浮选石英精砂中该指标;热力学计算表明pH≥5.5时淀粉基抑制剂CTSS与氧化铁表面铁离子发生化学键合的标准自由能变化ΔG为负值,化学键合具有自发趋势,抑制剂CTSS与含铁矿物的优先吸附是实现石英中性正浮选提纯的关键之一。

Iron oxide content is the main factor affecting the application of quartz in different fields. Because of the existing form, associated state, disseminated degree and particle size distribution of iron oxide disseminated quartz, conventional scrubbing, high-intensity electromagnetic and acid reverse flotation may not effectively decrease the content of ferric oxide. Using inhibitor to inhibiting iron-bearing minerals, ferric oxide content in quartz can be reduced by certain collector and foaming agent under the neutral condition. Results showed that under the combined action of synthetic organic inhibitor CTSS, amphoteric collector and foaming agent ZD-3, ferric oxide content in quartz could be reduced from 130- 150mg/kg to 60-100mg/kg, which meets the quality requirements for ultra white photovoltaic glass. Its upper limit of quartz grain for neutral flotation was 0.6mm, and better with ≤0.5mm, ferric oxide content in quartz purified by neutral flotation is lower than its purified by acid flotation aiming at the separation of iron aluminosilicate minerals and iron oxide disseminated in quartz. Thermodynamic calculations showed that at the chemically bonding between starch based inhibitor CTSS and ferric oxide may be natural at pH≥5.5, its standard Gibbs free energy change is negative, priority adsorption of CTSS is one of the keys to achieve quartz purification by neutral flotation.