全球高纯石英（SiO₂≥99.9%）资源分布极不均衡，我国优质石英矿床稀缺且高度依赖进口，开发替代性高纯石英资源已成为国家重大战略需求。煤系砂岩是煤炭开发过程中矸石的重要组成部分之一，分离提纯其中的石英资源，将有效推动煤炭行业的绿色转型升级，既能拓展煤系固废的利用途径，还能缓解环境压力，并为高纯石英资源的获取提供新的解决方案。

本研究以陕北黄陵矿区煤系细粒长石石英杂砂岩为对象，采用现代分析测试技术深入分析煤系砂岩基本性质的基础上，探讨了煤系砂岩的解离规律，系统研究了影响高纯石英提纯过程的各项因素及工艺条件。运用“擦洗—磁选—浮选—酸浸”的物理、化学方法联合提纯工艺，获得了3N5级高纯石英砂，分析总结了高纯石英的提纯机制。

显微及X射线衍射分析发现，黄陵矿区煤系砂岩为典型的细粒长石石英杂砂岩，主要由石英（60%）、长石（约25%）及杂基（15%）组成，含少量锆石、绢云母、磁铁矿、钛铁矿和煤屑，胶结物有泥质、硅质及少量方解石，方解石呈他形聚敛双晶。碎屑矿物石英具有紧密镶嵌结构、棱角状-次棱角状，部分颗粒具有次生加大，粒度均匀，粒径46~170 μm；石英颗粒内部含少量定向排列的短柱状锆石包裹体，锆石粒径10~30 μm，边界清晰，无溶蚀迹象。碎屑矿物长石结构致密，长石颗粒相对较小，粒径42~120 μm，形态多样，且具有典型的钠长石式聚片双晶结构（斜长石）。钾长石蚀变形成的鳞片状绢云母集合体见于长石颗粒边缘和裂隙处。杂基主要是蒙脱石微晶集合体。X射线荧光光谱显示，该砂岩中SiO₂、Al₂O₃、Fe₂O₃、CaO、K₂O含量分别为75.9%、17.02%、1.36%、1.57%和1.73%。

细粒长石石英杂砂岩中石英与长石等硬矿物在颚式破碎机高能冲击下优先沿颗粒边界或微裂隙解离，球磨机研磨作用进一步促使方解石胶结物和黏土矿物从碎屑表面剥离，导致细粒级占比显著升高。不同矿物解离行为受到多重因素影响，石英因硬度高、抗磨性强，破碎后仍以0.125~0.25 mm粒级为主，其棱角状形态在球磨过程中易产生次生裂隙，但完整晶体抑制了进一步细化；长石因双晶发育及绢云母化蚀变致其机械强度降低，在研磨中更易沿双晶面或蚀变带碎裂，部分进入0.045~0.125 mm或更低粒级，绢云母在细粒级中富集；方解石胶结物和蒙脱石作为次生矿物，因方解石硬度低及黏土矿物的层状结构，在球磨过程中优先解离为<0.045 mm的超细颗粒；黏土矿物杂基的高吸附性和可塑性，在破碎过程中易形成“软包裹”效应，阻碍石英与长石颗粒的完全解离，导致部分矿物仍以连生体形式存在于0.25~0.45 mm粒级中。

对进行粉碎预处理的砂岩样采用“擦洗—磁选—浮选—酸浸”工艺进行了石英提纯，该工艺中“物理初步提纯”阶段（擦洗—磁选—浮选）与“化学深度提纯”阶段（酸浸）的有效衔接对最终的提纯效果至关重要。擦洗脱泥最佳条件是：擦洗时间20 min、分散剂（KOH：(NaPO₃)₆）1:5、分散剂用量0.8%、矿浆浓度65%及搅拌速度1800 r/min。高梯度两段式磁选除Fe、Ti等元素的最佳条件是：脉动冲次200次/ min，磁感应强度为1.7 T。两次正浮选在中性环境下使用捕收剂PEA-D1000和抑制剂EDA进行，首次浮选PEA-D1000浓度为2×10⁻⁴ mol/L，EDA浓度为0.5×10⁻⁵ mol/L；二次浮选PEA-D1000浓度降至1×10⁻⁴ mol/L，深度脱除了砂岩中长石类杂质。煅烧水淬（1100℃，3 h）破坏了“物理提纯”后石英颗粒的晶体结构，使包裹体杂质暴露于表面；用混合酸（HNO₃ 30%、HCl 10%和HF 15%）在时间6 h、温度90℃、固液比1:4、酸用量40%对物理提纯产物深度提纯，获得了SiO₂含量99.95%的高纯石英。

对黄陵煤系砂岩进行高纯石英提纯结果分析表明，砂岩中石英转化为高纯石英的转化率达到39%，经济效益显著，市场前景广阔。

The global distribution of high-purity quartz (SiO₂ ≥ 99.9%) resources is extremely uneven. China faces a scarcity of high-quality quartz deposits and relies heavily on imports, making the development of alternative high-purity quartz resources a critical national strategic imperative. Coal-measure sandstone, a major component of gangue generated during coal exploitation, offers significant potential for quartz resource extraction. Purifying quartz from coal-measure sandstone not only promotes green transformation and upgrading in the coal industry but also expands the utilization pathways of coal-based solid waste, alleviates environmental pressures, and provides innovative solutions for securing high-purity quartz resources.

This study focuses on the coal measures fine-grained feldspathic quartz graywacke from the Huangling mining area in northern Shaanxi. Based on advanced analytical techniques to characterize the fundamental properties of the coal-measure sandstone, we investigated its dissociation law and systematically explored the influencing factors and process conditions for high-purity quartz purification. A combined physical-chemical purification process（"scrubbing-magnetic separation-flotation-acid leaching"）was optimized to produce 3N5-grade high-purity quartz. The purification mechanisms were comprehensively analyzed and summarized.

Microscopic and X-ray diffraction analyses revealed that the Huangling coal-measure sandstone is a typical fine-grained feldspar quartz graywacke, primarily composed of quartz (60%), feldspar (25%), and matrix (15%), with minor zircon, sericite, magnetite, ilmenite, and coal particle. The cementing materials include argillaceous, siliceous, and minor calcite components, with calcite exhibiting anhedral convergent twins. The detrital quartz exhibits a close-packed structure with angular-to-subangular grains, some displaying secondary overgrowths. The quartz grains are uniformly sized (46~170 μm) and contain sparse, oriented short-columnar zircon inclusions 10~30 μm in size, with clear boundaries and no signs of dissolution. Detrital feldspar grains (42~120 μm) exhibited dense structures, diverse morphologies, and typical albite polysynthetic twinning (plagioclase). Sericite aggregates, formed by potassium feldspar alteration, are observed at feldspar grain margins and fractures. The matrix predominantly consisted of montmorillonite microcrystalline aggregates. X-ray fluorescence spectroscopy showed SiO₂、Al₂O₃、Fe₂O₃、CaO、K₂O contents of 75.9%、17.02%、1.36%、1.57% and 1.73% respectively within the sandstone.

The fine-grained feldspar quartz graywacke under high-energy impact from jaw crushers, quartz and feldspar were preferentially liberated along grain boundaries or microcracks. Subsequent ball milling further stripped calcite cement and clay minerals from detrital surfaces, significantly increasing the proportion of fine particles. Liberation behavior varied with mineral properties, Quartz due to characterized by high hardness and abrasion resistance, remained predominantly in the 0.125~0.25 mm fraction after crushing. Its angular morphology facilitated secondary crack generation during milling but inhibited further refinement due to crystal integrity. Feldspar due to weakened by polysynthetic twinning and sericitization, fractured preferentially along twin planes or alteration zones during grinding, resulting in enrichment in the 0.045~0.125 mm or finer fractions. Sericite accumulated in fine-grained fractions. Calcite cements and montmorillonite due to their low hardness and layered structure, preferentially dissociated into <0.045 mm ultrafine particles. The adhesive and plastic nature of clay matrix induced a "soft encapsulation" effect, hindering complete liberation of quartz and feldspar, leaving some mineral intergrowths in the 0.25~0.45 mm fraction.

Quartz purification of sandstone samples pretreated by grinding was carried out by “scrubbing-magnetic separation-flotation-acid leaching” process. In this process, the effective connection between “physical purification” stage (scrubbing-magnetic separation-flotation) and “chemical purification” stage (acid leaching) is very important for the final purification effect. The optimum conditions for desliming are: scrub time 20 min, dispersant (KOH: (NaPO₃)₆) 1:5, dispersant dosage 0.8%, slurry concentration 65% and stirring speed 1800 r/min. The optimum conditions for the removal of Fe, Ti and other elements by high gradient two-stage magnetic separation are as follows: the pulsation frequency is 200 times / min, and the magnetic induction intensity is 1.7 T. Two direct flotations were carried out in a neutral environment using the collector PEA-D1000 and the inhibitor EDA. The concentration of PEA-D1000 was 2 × 10⁻⁴ mol/L and the concentration of EDA was 0.5 × 10⁻⁵ mol/L in the first flotation. The concentration of PEA-D1000 in the secondary flotation was reduced to 1 × 10⁻⁴ mol/L, and the feldspar impurities in the sandstone were removed in depth. Calcination and water quenching (1100°C, 3 h) destroyed the crystal structure of the quartz particles after ' physical purification ', exposing the inclusions to the surface. High purity quartz with SiO₂ content of 99.95% was obtained by deep purification of the physical purified product with mixed acid (HNO₃ 30%, HCl 10% and HF 15%) at time of 6 h, temperature of 90°C, solid-liquid ratio of 1:4 and acid dosage of 40%.

The results of high-purity quartz purification of Huangling coal measures sandstone showed that 39 % of quartz in sandstone was converted into high-purity quartz sand, which has significant economic benefits and broad market prospects.