硅矿石资源勘查评价与可持续发展策略

我国的硅矿石资源储量居世界第一,且产量居世界前列。随着多年的勘查与开发,硅矿石的开发利用已由传统领域向新的应用领域拓展。结合谷城县的硅矿石资源开发现状,首先分析对硅矿石资源进行勘查评价的必要性,其次分析资源勘查的技术和方法,以及评价硅矿石资源潜力的指标体系,最后阐述可持续发展策略,包括节约利用、循环利用、提高资源利用率等。

用脂肪酸从碳酸盐和含硅矿石中选择性浮选磷酸盐的新工艺

用脂肪酸作捕收剂从共生的(Ca、Mg)碳酸盐和硅质脉石矿物中,选择性浮选沉积型磷灰石“细晶磷灰石”已获成功。这一工艺是由阿拉巴马大学的矿物资源学院(MRI)提出的,它包括在pH=3—6条件下从磷酸盐中快速浮选碳酸盐和在pH=5—7条件下从含硅杂质中浮选磷酸盐,或这两种工艺之一。该工艺充分利用这些矿物在弱酸性条件下的稳定性和溶解性的差异和对脂肪酸吸附及浮选行为的差异,并根据脂肪酸捕收剂的物理吸附行为提出了分选机理。应用MRI快速碳酸盐浮选工艺浮选三种产于亚洲含白云石和钙质的磷酸盐(硅含量低),这三种磷酸盐含19—23％P_2O_(?)、40—60％(Ca,Mg)CO_3,生产出高品位的磷酸盐精矿,其位为36—38％P_2O_5、0.08％MgO、不溶物含量为6％,而P_2O_5的回收率高达80—85％。美国犹他州和佛罗里达州南部的碳酸盐型磷酸盐含硅量高,10—16％P_2O_5,1-2％MgO,不溶物为40-64％,其分选需要同时采用快速碳酸盐浮选和磷酸盐浮选两种工艺。两步MRI工艺生产的磷酸盐精矿含31％P_2为O_5、8.8MgO、不溶物为4％,相应的P_2O_5回收率为82—84％。而磷酸盐正浮选法则应用于浮选佛罗里达州中部和北部、加利福尼亚州北部和西班牙的低品位含硅磷酸盐矿石。这些地方产出的矿石含6—23％P_2为O_5,不溶物占28—70％。该工艺生产出适合市场销售的产品:30-33％P_2O_5、回收率86—92％。

低等级粉煤灰-高硅矿石复合掺合料制备及性能

矿物掺合料已经成为现代混凝土不可或缺的重要原材料之一,限于环保要求,目前普遍使用的矿渣粉和粉煤灰等掺合料面临资源短缺及价格上涨问题。为开拓矿物掺合料新市场,提出以低等级粉煤灰和高硅矿石制备混凝土用复合掺合料,研究复合掺合料各项性能并探索其技术可行性。研究结果表明:低等级粉煤灰和高硅矿石粉复合,能够调节复合掺合料的化学组成,使之满足于相关标准需要;但是利用低等级粉煤灰和高硅矿石粉制备的复合掺合料的工作性和力学性能基本介于低等级粉煤灰和高硅矿石粉之间,两者性能和功能叠加效应并不明显。

钴改性硅矿石/臭氧催化氧化环丙沙星的性能

采用浸渍法制备Co_3O_4/硅矿石复合催化剂(CoSO),并对制备条件进行了优化。通过EDS、XRD、BET等方法对催化剂进行表征,同时比较了单独臭氧氧化、硅矿石吸附、CoSO吸附、SO/臭氧催化氧化和CoSO/臭氧催化氧化体系对环丙沙星(CIP)的降解能力。结果表明,Co_3O_4可成功负载于天然硅矿石表面,当浸渍液(硝酸钴)浓度为0. 5 mol/L、焙烧时间为5 h、焙烧温度为500℃时,制备的CoSO复合催化剂活性最高。采用CoSO/臭氧催化氧化CIP,30 min后对CIP的去除率为91. 5%,比单独臭氧氧化及SO/臭氧催化氧化分别提高了49%和25%。另外,单独臭氧氧化、SO/臭氧催化氧化和CoSO/臭氧催化氧化体系对CIP的降解过程符合拟一级反应动力学,并且CoSO/臭氧催化氧化体系对CIP的降解动力学常数为0. 082 min^(-1),分别为单独臭氧氧化和SO/臭氧催化氧化的4. 8和2. 4倍。

钠盐强化某高硅低品位铁矿石内配碳球团自还原机理研究

研究了含钠添加剂强化某高硅低品位铁矿石内配碳球团的还原过程,并借助光学显微镜和扫描电镜分析了含钠添加剂掺量对内配碳球团还原行为及其强度变化的影响。结果表明:球团中配加含钠添加剂不仅可明显强化该铁矿石的还原行为,大幅度提高焙烧球团的金属化率及其磨选产品的铁品位,同时还可明显提高焙烧球团的强度,降低焙烧球团的粉化率。钠盐配加量为3%的内配碳球团在960℃下还原40 min,所得焙烧产物的金属化率为86.21%,产品铁晶粒增大、连晶增多,孔洞显著减少,结构致密,还原过程的粉化率降至2.57%;焙烧产品在磨矿细度为-0.045 mm占96.15%情况下进行弱磁选(磁场强度180 k A/m),获得的精矿铁品位为87.93%,明显优于不添加钠盐情况下的指标(金属化率为45.62%,粉化率为35.39%,精矿铁品位为58.12%)。

矿石铝硅比对拜耳法溶出效果影响的试验

对铝硅比从５～１６的河南贾沟矿，进行了拜耳法溶出的试验。探索矿石铝硅比对溶出效果的影响。研究采取不同强化措施对低铝硅比矿石溶出效果的影响和低铝硅比矿石溶出赤泥的沉降性能。

某高硅复杂金矿石中金银含量测定方法研究

近几年,我国经济发展迅速,矿产企业为我国做出了很大贡献。金矿石中金银的测定目前没有标准方法,一般借鉴金精矿中金的经典测定方法GB/T7739.1-2007,在用该方法测定含有较高二氧化硅的金矿石样品时,在火法熔融过程中熔液容易溢出坩埚,导致试验失败;同时由于样品中含有较微量的银,形成的金银合粒中,银量和金量的比例相差甚大,给分金环节带来极大困难,金银合粒甚至无法有效分离。基于此,响应国家节能、减排、降耗的号召,根据该类样品的性质,通过试验进行了研究,通过不断改变固体熔剂的用量,优化并建立一次造渣铅扣适宜的试验条件,同时通过补加纯银,弥补样品中银量与金量的比例缺陷。在优化的工作条件下经过验证,分析结果准确、快速,减少了反复造渣引起的环境污染,减小了劳动强度和难度,检测成本大幅降低,现已用于大批高硅复杂金矿石中金银含量的测定,并取得了很好的效果。该方法适用于金矿石中含金量为100-600g/t与含银量为30-100g/t的测定。

新型硅酸锡微孔化合物的合成与表征

利用水热合成法制备了一种新型硅酸锡微孔化合物(Microporous stannosilicates),通过XRD,SEM,29Si MAS NMR,119Sn MAS NMR,IR和TG等测试手段对该硅酸锡微孔化合物进行了表征.结果表明,该硅酸锡微孔化合物中的Sn物种为六配位形式,而此化合物与硅锆矿石(Litvinskite)具有相同的拓扑结构.

Bio-desilication of rutile concentrate and analysis of community structure in bio-desilication reactor

The original strain HY-7 was isolated from the bauxite mine drainage（BMD） taken from a reservoir in Sanmenxia Mine,Henan Province,China.The optimum temperature and pH for the growth of strain HY-7 were 30 ℃ and 7.0,respectively.The optimum UV radiating time was 20 s and the positive mutation rate was 23.0%.The growth curves show that strain HY-7 needs144 h to reach the stationary phase after its mutagenesis,which is 24 h earlier than that of the original strain.Sequence homology analysis indicated that this community consisted of mainly two branches：one sharing high homology with Paenibacillus stellifer and the other sharing high homology with Sporolactobacillus laevolacticus.The experimental results showed that the TiO2 grade of mtile concentrate increased from 78.21%to 91.80%and the recovery of TiO2 reached 95.24%after 7 d of bioleaching.The bio-desilication process can not only effectively improve the TiO2 grade of rutile concentrate but also meet the requirements of environmental protection.

Pressure leaching of zinc silicate ore in sulfuric acid medium

Zinc silicate ore was characterized mineralogically and the results showed that zinc exists mainly as hemimorphite and smithsonite in the sample.Sulfuric acid pressure leaching of zinc silicate ore was carried out to assess the effect of particle size,sulfuric acid concentration,pressure,reaction time and temperature on the extraction of zinc and the dissolution of silica.Under the optimum conditions employed,up to 99.25% of zinc extraction and 0.20% silica dissolution are obtained.The main minerals in leaching residue are quartz and small amounts of undissolved oxide minerals of iron,lead and aluminum are associated with quartz.

Ore petrography of low-grade siliceous manganese ores from the Bonai-Keonjhar belt, Orissa, India: The influence of mineral-fabric on their beneficiation

Low grade siliceous manganese ores from the iron ore group of the Bonai-Keonjhar belt, Orissa, India are found mostly in shear zones. The ore characteristics of siliceous manganese ore samples from three differ- ent mines, viz. the Shankar (Barbil OMC lease hold area), the Sone-Patuli (Patmunda, OMM lease hold area), and the Musaghar (Roida, OMDC lease hold area), were studied. These siliceous manganese ores are of three types, respectively: (i) spongy-granular; (ii) massive-mosaic; and (iii) hard-mylonitized. The spongy-gran- ular type contains granular, saccharoidal quartz and the major manganese mineral present is pyrolusite. The second type contains well crystallized quartz and cryptomelane, while the third has cherty, fine grained quartz (mylonite) along with romanechite. All three ores were subjected to physical beneficiation under similar conditions. Both gravity and magnetic separation techniques were employed. The mineral-fabric of the ores has been correlated to the extent of their beneficiation using these physical techniques. Of these three ores only the spongy-granular type responded well to upgrading. The feed with 22% Mn content could be upgraded to 44% with a 28% yield and a 49% recovery. The good response to beneficiation of the spongy- granular sample could be due to the large euhedral crystals of pyrolusite and the friable nature of the sac- charoidal quartz. This study reveals the influence of mineral-fabric on beneficiation of low grade ore, siliceous Mn ore in particular.

Effect of Perched Water Tables on Aluminosilicate Stability and Soil Genesis

The mineral stability and solute activities of soil solution extracted from selected horizons of seven studied pedons of Alfisols in Kentucky, USA, and the relationship between distribution of iron-manganese concretions and the restrictive layers were investigated. The results showed that the genesis and development of these soils and mineral weathering trends were strongly influenced by the depth of bedrock and the presence of perched water tables at lithic (limestone) interfaces due to the dissolution and buffering effect of limestone bedrock. The extractable Mg/Ca ratio as depth function and soil depth above bedrock could be used as indices of weathering and degree of soil development. Maximum iron-manganese concretion accumulation was found to occur in the horizon overlying clay horizon (>40% clay) with a sharp increase in clay content (>10%), which suggested that zones of Fe-Mn concretion accumulation in soils of the Inner Bluegrass Region appeared to be a sensitive genetic indicator of argillic horizons with restrictive permeability.

Efficient separation of alumina and silica in reduction-roasted kaolin by alkali leaching

Alkali leaching was employed to investigate the separation of alumina and silica in roasted kaolin obtained by roasting kaolin alone in air at 1273 K for 60 min and in clinker prepared by roasting the mixed raw meal of kaolin,ferric oxide and coal powder with Fe2O3/Al2O3/C molar ratio of 1.2:2.0:1.2 in reducing atmosphere at 1373 K for 60 min.The thermodynamic analyses and alkali leaching results show that the composition of the Al-Si spinel in roasted kaolin is close to that of 3Al2O3·2SiO2 and the spinel is dissolved with increasing leaching time,resulting in difficulty in deeply separating alumina and silica in kaolin by the traditional roasting-leaching process.On the contrary,the efficient separation of alumina and silica in kaolin can be reached by fully converting kaolinite into insoluble hercynite and soluble free silica,namely quartz solid solution and cristobalite solid solution,during reduction roasting,followed by alkali leaching of the obtained clinker.Furthermore,experimental results from treating high-silica diasporic bauxite indicate that the reduction roasting-alkali leaching process is potential to separate silica and alumina in aluminosilicates.

Beneficiation of a low grade limestone sample

Pilot scale column flotation studies were conducted on a low grade siliceous limestone ore. Silica content was reduced to less than 13g in the concentrate so that it became satisfactory for use in the paper or rubber industries. The limestone sample was crystalline and constituted primarily of calcite that contained quartz, feldspar, pyroxene, and biotite as gangue minerals. Quartz is the major silicate gangue whereas feldspar, pyroxene, and biotite exist in minor to trace quantities. Traces of pyrite were also observed within the sample. A reverse flotation process was adopted where the silicate gangue minerals were floated using two different commercial cationic collectors： Chem-750 F or Floatamine-D. The studies clearly suggest it is possible to produce a limestone concentrate assaying around 96-97% CaCO3 containing less than 1 % Si02. The effect of feed flow rate, percent solids, froth depth, and wash water on the grade and recovery of the CaC03 concentrate is discussed.

Effects of different factors during the de-silication of diaspore by direct flotation

Most of the bauxite resources in China are kaolinite-diaspore bauxite of middle to low grade, with a fine dissemination, and are difficultly separated. Direct flotation de-silication has been shown to be an effec- tive method for de-silication of diaspore. In this study the effect of different factors, including pulp tem- perature, density, pH value, depressant, and collector dosage, on direct flotation of diaspore were investigated by laboratory experiments. The optimum conditions were identified and the flotation perfor- mance was improved. The results show that under optimum conditions （a pulp temperature around 40℃, a pulp density from 30% to 33g, a pH value from 9.0 to 10.0, an air flow rate of 0.5 m3/（m2 rain）, a dispersant level from 35 to 70 g/t, and a collector level around 1000 g/t） an AI/Si ratio of 6.97 is obtained starting from an initial Al/Si ratio of about 4.71. The recovery of A1203 under these conditions was 86.94%.

Effect of Fe_2O_3/SiO_2 ratio on maghemite-silica particulate nanocomposites

Abstract： Maghemite-silica particulate nanocomposites were prepared by modified 2-step sol-gel process. Superparamagnetic maghemite nanoparticles were successfully produced using Massart＇s procedure. Nanocomposites consisting of synthesized maghemite nanoparticles and silica were produced by dispersing the as-synthesized maghemite nanoparticles into the silica particulate form. The system was then heated at 140 ℃for 3 d. A variety of mass ratios of Fe2O3/SiO2 was investigated. Moreover, no surfactant or other unnecessary precursor was involved. The nanocomposites were characterized using XRD, BET and AGM. The XRD diffraction patterns show the reflection corresponding to maghemite nanoparticles and a visible wide band at 20 from 20° to 35° which are the characteristics of the amorphous phase of the silica gel. The patterns also exhibit the presence of only maghemite and SiO2 amorphous phase, which indicates that there is no chemical reaction between the silica particulate gel and maghemite nanoparticles to form other compounds. The calculated crystallite size for encapsulated maghemite nanoparticles is smaller than the as-synthesized maghemite nanoparticles indicating the dissolution of the nanoparticles. Very high surface area is attained for the produced nanocomposites （360-390 m^2/g）. This enhances the sensitivity and the reactivity of the nanocomposites. The shapes of the magnetization curves for nanocomposites are very similar to the as-synthesized maghemite nanoparticles. Superparamagnetic behaviour is exhibited by all samples, indicating that the size of the maghemite nanoparticles is always within the nanometre range. The increase in iron content gives rise to a small particle growth.

基于FLAC3D的颚式破碎机工作性能分析与研究

为了提高颚式破碎机的破碎效果,针对影响其破碎效果的主要因素,以硅矿石作为破碎物,利用3个球面建立大、中、小硅矿石的离散元模型来表达其几何特征,基于FLAC3D的正交旋转组合仿真研究动颚板行程、齿形角、肘板摆角对硅矿石破碎键数目的影响,并通过SPSS获得硅矿石破碎键数目的回归方程,由Matlab内的fmincon模块解析出圆整后的数值。结果表明,动颚板行程对矿石破碎键数目影响最大,其次为齿形角,最小为肘板摆角。当齿形角为153°,动颚板行程为182mm,肘板摆角为27°时,破碎腔内的单个硅矿石破碎键数目为267个。对比仿真与试验结果,验证了FLAC3D研究颚式破碎机破碎效果的可行性。

Occurrence andmineral chemistry of chromite and xieite in the Suizhou L6 chondrite

The occurrence and mineral chemistry of chromite and its high-pressure phase xieite in the Suizhou meteorite were studied by different modem micromineralogical techniques. Three types of occurrences for chromite were observed in the Suizhou L6 chondrite： coarse chromite grains, cluster of chromite fragments in molten plagioclase, and exsolution lamellar chromite in oli- vine. All the chromite grains of the first two types are remarkably similar in chemical compositions, but the composition of exsolution chromite is inhomogeneous and variable in A1203 content. Xieite is a post-spinel CT-phase of chromite firstly found in the Suizhou meteorite. Three types of occurrences of xieite have also been revealed in this meteorite： coarse xieite grains, complex three-zone-grains consisting of the inner xieite, the intermediate lamellae-like CF-phase and the outer chromite phase, and two-phase-grains consisting of xieite and one of the high-pressure silicate minerals lingunite, ringwoodite or majorite. The curved boundary between xieite and the silicate half in two-phase grains is indicative of some partial or even full melting of the silicate phase. EPMA and EDS results show that the compositions of xieite inside/contacting the shock veins are also identical to that of chromite outside the veins. However, some element diffusion appeared in between the xieite and the silicate half in the two-phase grains, namely, some of Al^3＋ from lingunite, or Fe^2＋ from ringwoodite migrated to xieite, and some of Cr^3＋ migrated from xieite to lingunite or ringwoodite. Majorite in two-phase grains shows remarkable decrease of SiO2 and MgO, and notable increase of Al2O3 and CaO, indicating that its host mineral pyroxene was fully molten and mixed with the surrounding silicate melt of the vein matrix. The complexity in mineral chemistry of these two-phase grains in shock veins can be explained by the much higher shock peak temperature in shock veins （1800-2000℃） than in unmelted main body （-1000℃）, and by the much lower density of the silicate minerals （2.6-3.3 g/cm3） than that of chromite （4.43 g/cm^3）. Being a refractory and a rela-tively high-impedance material, chromite is chemically more stable and easier to reflect shock wave into the silicate half causing the partial or even full melting of silicate phases, upon which some diffusion of elements between the two phases them-selves, or even mixing of molten pyroxene and the surrounding silicate melt.

CO_2 Sequestration from flue gas by direct aqueous mineral carbonation of wollastonite

Emission of carbon dioxide is considered to be the main cause of the greenhouse effect. Mineral carbonation, an important part of the CCS technology, is an attractive option for long-term CO2 sequestration. In this study, wollastonite was chosen as the feedstock and the feasibility of direct aqueous mineral carbonation in the simulated flue gas was investigated via a series of experimental studies carried in a stirred reactor. X-ray diffraction （XRD）, X-ray fluorescence spectroscopy （XRF）, ion chro- matography （IC） and thermal decomposition were used to determine the carbonation conversion. The influences of various factors, including reaction temperature, reaction pressure, solution composition, heat-treatment and particle size, were dis- cussed. Concurrently, the effects of SO2 and NO presented in simulated flue gas were also investigated and a possible mecha- nism was used to explain the results. Experimental results show that reaction temperature, reaction pressure and particle size can effectively improve the carbonation reaction. Addition of 0.6 M NaHCO3 was also proved to be beneficial to the reaction and heat-treatment is not needed for wollastonite to get a higher carbonation conversion. Compared with carbonation in puri- fied CO2 gas, CO2 sequestration directly from simulated flue gas by mineral carbonation is suggested to have a certain degree of economic feasibility in the conditions of medium and low-pressure. A highest carbonation conversion of 35.9% is gained on the condition of T=150℃, P=40 bar and PS 〈30 μ in distilled water for 1 h.