The Origin and Preservation of Suspended Barites near the 90°E Ridge in the Northeastern Indian Ocean

Suspended particulate barite crystals were detected in the water columns at four different stations near the 90°E ridge in the Indian Ocean.Four distinct morphological types of marine barites were distinguished:euhedral-subhedral crystals,oval or round crystals,rhombic crystals,and irregular crystals.The barite crystals in the study area are typically fine,with a dominant size of 1–3μm.The vertical distribution of barites is significantly affected by the formation and sedimentation processes.Barites begin to appear at a depth of 30 m and are formed primarily from the surface to the depth of 2000m with a concentration peak at the depth of 200m,where particles are coarser than those in the other layers.The barites begin to settle and dissolve once formed in the water column,resulting in finer barite particles and lower particle concentrations.The formation of barite crystals is related to biological processes associated with the decomposition of barium-rich skeletons in the microenvironment of decaying organic matter that is affected by the primary productivity and dissolved oxygen content in the water column.The dissolving process of barite crystals showed similar variation with the concentration of dissolved barium in ocean water,and the substitution of strontium for barite in crystals promotes the selective dissolution of barite and exerts an important impact on its morphology.It is approximately 33%of barites in the amount and 22%in the concentration to settle to the bottom of the water column compared to that observed in the main barite formation zone.

Surface modification of barite nanoparticles using stearate

In this study, the barite nanoparticles were successfully modified with stearate and the influence of stearate addition on the performance of barite nanoparticles was systematically investigated. The products were characterized by activating factor analysis, contact angle test, surface energy calculation, sedimentation rate calculation, rheological measurement, and FT-IR analysis, etc. As the quantity of added stearate increased, both the activating factor and contact angle of barite nanoparticles increased first then decreased. When the stearate content was 5% of the mass of barite nanoparticles, the activating factor and water contact angle of modified particles reached maximum value, 97% and 126% respectively. At this time, the sedimentation rate reached minimum, and so did the surface energy. The rheological test reveals that the viscosity of modified barite nanoparticles/petronol system decreases greatly, indicating the surface performance of barite nanoparticles has changed from hydrophilicity to lipophilicity after modification. C=O and COO stretching vibration peaks were found in the FT-IR spectra, which proves that the stearate has combined onto the surface of barite nanoparticles. Finally, according to the zeta potential result of unmodified barite, the possible modification mechanism was provided.

Crystals of suspended marine barite in the eastern equatorial Pacific:processes of dissolution and effects on crystal morphology

Suspended particulate substances were sampled in the eastem equatorial Pacific in water column from surface to near bottom in five stations in 2005, from which 868 barite crystals were recovered. The barite crystals were examined under scanning electron microscopy. About 61% of the total barites crystals contained detectable Sr by energy dispersive X-ray spectrometry. Barite crystals could be classified into four groups based on their morphology： 1） bladed; 2） ovoid or rounded; 3） arrow-like; and 4） irregularly shaped. The arrow-like barite crystals in natural environment has never been reported before. In addition, about a half of the studied crystals showed features of dissolution as cavities or holes inside of the crystals or around their edges. We found that differential dissolution of barite crystals is consequence of heterogeneous Sr distribution in barite crystals. Our results would help in understanding the biogeochemical processes of marine barite formation and preservation in seawater and marine sediments.

Strontium Isotope Compositions of Hydrothermal Barite from the Yonaguni Ⅳ: Insight into Fluid/Sediment Interaction and Barite Crystallization Condition

Hydrothermal barite is a typical low-temperature mineral formed during the mixing of hydrothermal fluid and seawater.Because of its extremely low solubility,barite behaves as a close system after crystallization and preserves the geochemical fingerprint of hydrothermal fluid.In this study,the elemental contents and Sr isotope compositions of hydrothermal barites from the Yonaguni IV were determined using electron microprobe and LA-MC-ICP-MS respectively.On these bases,the fluid/sediment interaction during the hydrothermal circulation and physicochemical condition of barite crystallization were discussed.Results show that the 87 Sr/86 Sr values of hydrothermal barites from the Yonaguni IV are apparently higher than those of the seawater and associated volcanic rocks,indicating the sufficient interaction between the hydrothermal fluid and overlying sediment.Monomineral Sr abundance shows large variations,reflecting the changes in barite growth rate during the fluid mixing.The mineralization condition in the Yonaguni IV was unstable.During the crystallization of barite,hydrothermal fluid and seawater mixed in varying degrees,with the pro-portions of hydrothermal fluid varied from 36%to 72%.The calculated crystallization temperatures range from 109 to 220℃.Sediment plays a critical role during the mineralization process in the Yonaguni IV and incorporation of sediment component into hydrothermal system was prior to barite crystallization and sulfide mineralization.

Microtexture and Distribution of Minerals in Hydrothermal Barite-Silica Chimney from the Franklin Seamount, SW Pacific: Constraints on Mode of Formation

An extinct hydrothermal barite-silica chimney from the Franklin Seamount of the Woodlark Basin, in the southwestern Pacific Ocean, was investigated for mineral distribution and geochemical composition. Six layers on either side of the orifice of a chimney show significant disparity in color, mineral assemblage and major element composition. Electron microscope（SEM） images reveal that the peripheral wall of the chimney is composed of colloform silica, suggesting that incipient precipitation of silica-saturated hydrothermal fluid initiated the development of the chimney wall. Intermediate layers, between the exterior wall and the inner fluid-orifice, dominate with barite and sulfides. Low Sr-to-Ba ratios（SrO/BaO = 0.015–0.017） indicate restricted fluid-seawater mixing, which causes relatively high-temperature formation of the intermediate layers. Whereas the innermost layer bordering the chimney orifice is characterized by more silica and a higher Sr-to-Ba ratio（SrO/BaO = 0.023）, could have formed due to a paragenetic shift from a high-temperature active phase to a cooler waning stage of formation. A paragenetic shift is also probably responsible for the change in mineral formation mechanism that resulted in the textural variation of barite and colloform silica developed during different growth phases of this barite-silica chimney.

Cost-effective integrated strategy for the fabrication of hard-magnet barium hexaferrite powders from low-grade barite ore

Ultrafine barium hexaferrite（BaFe12O19） powders were synthesized from the metallurgical extracts of low-grade Egyptian barite ore via a co-precipitation route. Hydrometallurgical treatment of barite ore was systematically studied to achieve the maximum dissolution efficiency of Fe（～99.7%） under the optimum conditions. The hexaferrite precursors were obtained by the co-precipitation of BaS produced by the reduction of barite ore with carbon at 1273 K and then dissolved in diluted HCl and FeCl3 solution at pH 10 using NaOH as a base; the product was then annealed at 1273 K in an open atmosphere. The effect of Fe^3＋/Ba^2＋ molar ratio and the addition of hydrogen peroxide（H2O2） on the phase structure, crystallite size, morphology, and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. Single-phase BaFe（12）O（19） powder was obtained at an Fe^3＋/Ba^2＋ molar ratio of 8.00. The formed powders exhibited a hexagonal platelet-like structure. Good maximum magnetization（48.3 A×m^2×kg^–1） was achieved in the material prepared at an Fe^3＋/Ba^2＋ molar ratio of 8.0 in the presence of 5% H2O2 as an oxidizer and at 1273 K because of the formation of a uniform, hexagonal-shaped structure.

Discovery of an abnormally high-δ^(34)S barite deposit and a new understanding of global sulfur isotope variation during geological history

The evolution of the global sulfur isotope curve was plotted based on the δ34S values of evaporates resultant from oceanic evaporation. In the long period of geological history the δ34S values showed obvious peaks for three times during the process of ancient oceans' sulfur isotope evolution, namely the Early Cambrian (+30‰), the Late Devonian (+25‰) and the Permian-Triassic transition interval (+17‰), but the causes of the abnormal rise of sulfur isotopic values during the geological period are still in question. In this paper, 18 samples collected from a large Devonian barite deposit from Zhenning County were analyzed to determine their δ34S values, revealing that the 18 samples have very high δ34S values (δ34S=41.88‰-+68.39‰), with an average close to 56.30‰, which are higher than the isotopic values of contemporary sulfates (+17‰- +25‰). A comparative analysis was conducted of the emerging of high δ34S barite deposits (from Cambrian and Devonian) and the δ34S variation curves of the ancient oceans. The results indicate that the time when the obvious peaks of δ34S values appeared and the time of massive sedimentation of high δ34S barite deposits are very close to each other, which, in our opinion, is not a coincidence. There may exist some correlations between the sulfur isotope evolution of ancient oceans during the diverse periods of geological history and the massive sedimentation of high δ34S barite deposits. Therefore, it is inferred that perhaps it was the massive sedimentation of high δ34S barites that caused the sharp rise of δ34S values in a short period of time.

THE INFLUENCE OF IMPURITIES ON THE DISSOLUTION OF CA- AND SR-BEARING BARITE AT ROOM TEMPERATURE

The reaction path in the (Ba, Sr, Ca)SO-4 solid-solution aqueous-solution (SSAS) system was experimentally studied using a batch-reactor method. The effect of the impurities "fluorite" and "iron sulfides" admixed in a natural barite sample on the reaction path was followed by analyzing the aqueous solution continuously. The dissolution and precipitation of the impurity "fluorite" affected strongly the reaction path in the SSAS system, especially the Ca/Sr/Ba ratio in the aqueous solution. This influence became stronger with decreasing CaSO-4 in the solid solution. The dissolution and precipitation of fluorite could hinder the CaSO-4 component from dissolving into water, and reduce the release rate of SO{2-}-4 from the solid solution to the aqueous solution and the removing rate of Ba{2} from the aqueous solution. In the presence of fluorite and sulfides, the aqueous Ba{2} and Sr{2} concentrations were controlled by the dissolution-precipitation of the end-members BaSO-4 and SrSO-4, respectively; the aqueous F-, Ca{2} and SO{2-}-4 concentrations were controlled by the dissolution-precipitation of fluorite. The incongruent dissolution of the (Ba, Sr, Ca)SO-4 solid solution caused the solid phase to become progressively more enriched in the more insoluble component (BaSO-4), while the aqueous composition shifted towards the more soluble end-members (SrSO-4 and CaSO-4) as equilibrium was approached to.

The Bulong Gold Deposit-a Quartz-Barite Vein Type Gold Deposit in Xinjiang:Geological Characteristics and S, He and Ar Isotopic Compositions

The Bulong gold deposit, located in the southwest Tianshan in China, occurs in the Upper Devonian finegrained clastic rocks. The gold orebodies are controlled by an gently inclined interlayer fractured zone. They are hosted only in quartz-barite veins though there are barite veins and quartz veins in the ore district. The δ34S values of pyrite in the ores range from 14.6‰ to 19.2‰ and those of barite from 35.0‰ to 39.6‰, indicating that the sulfur was derived from the strata. 3He/4He ratios of fluid inclusions in pyrite are 0.24-0.82 R/Ra, approximating to that of the crust. The 40Ar/39Ar ratios range from 338 to 471, slightly higher than that of the atmosphere. 40Ar /4He ratios of ore fluids range from 0.015 to 0.412 with a mean of 0.153. Helium and argon isotope compositions of fluid inclusions show that the ore fluids of the Bulong gold deposit were mainly derived from the crust.

Investigations on the Possible Re-equilibration of Aqueous Fluid Inclusions in Barite:A Study of Barite and Calcite from the Hutti Gold Deposit,Karnataka,India

Re-equilibration of fluid inclusions in crystals takes place by loss or gain of solvents and solutes from fluid inclusions and by changes in their volumes. Volume change of fluid inclusions are primarily dictated by elastic properties and available slip planes of host crystals. In the present study, the phase-behavior of fluids entrapped in co-precipitated calcite and barite is studied. While calcite contains only biphase fluid inclusions, barite has predominantly monophase fluid inclusions. Fluid inclusion petrography, microthermometry and leachate analysis are used to establish the nature of entrapped fluids and entrapment temperature is substantiated through independent sulfur isotope geothermometry using coexisting barite and pyrite. Phase transitions in the monophase fluid inclusions in barite are explained in terms of over-pressuring of fluids in these fluid inclusions relative to fluids entrapped in calcite owing to the low bulk modulus of barite.

Assessment of Heavy Metals Concentration and Enrichment Levels in Soils around Quarries and Barite Mine Sites in Part of Akamkpa and Biase Area, Southeastern Nigeria

Geochemical investigation of the soils around quarry and barite mine sites in part of Akamkpa and Biase area of Southeastern Nigeria, was carried out to assess the concentration and enrichment levels of some heavy metals and trace elements in the soils. The investigation involved the collection of fifteen (15) soil samples between the depth of 15 - 30 cm. The samples were dried at room temperature, prepared and analyzed for heavy metals using inductively couple plasma mass spectrometer. The result shows that the concentration of Co, Cr, Nb, Pb and Sn were higher than the average shale values around the quarries while Ba, Pb and Sn were higher around the barite mines. The contamination factor indicates low to minimal contamination and low to considerable contamination around the quarries and barite mines respectively. While the Enrichment factor indicates minimal to significant enrichment around the quarries and minimal to extremely high enrichments around the barite mines. The result of the factor analysis and spatial distribution of the heavy metals suggests that the metal concentration and enrichment were controlled by the rock types, weathering and anthropogenic activities around the mine sites.

贵州镇宁-紫云泥盆系大型沉积重晶石矿床成矿过程研究

古生代是全球沉积型重晶石矿床成矿的重要时期,这一时期在全球范围内形成了多个大型和超大型重晶石矿。特别是在扬子陆块西南缘的镇宁-紫云地区,发育一个泥盆系大型沉积重晶石矿床,其资源储量逾6000万吨。本文在已有研究基础上,结合最新的野外调查和研究成果,探讨了重晶石成矿过程、成矿规律和关键控矿要素。研究认为,重晶石矿床成矿与甲烷渗漏活动存在成因上的联系。水城-紫云-南丹裂陷槽内次级盆地对矿体的形态和空间展布有重要控制和影响作用。在含矿岩系出露区,矿体明显呈透镜状赋存于上泥盆统响水洞组硅质建造之中,并且显示出从NW至SE厚度不断减薄的规律性变化。结合Sr、S、C、O同位素组成,推断乐纪一带可能更靠近重晶石成矿的中心。甲烷渗漏强度及其消耗途径变化是不同剖面之间重晶石矿体厚度及其共生灰岩的产出特征和数量在空间上存在差异性的主要控制因素。综合研究,将重晶石成矿过程划分为成矿前、成矿期、成矿后三个阶段,并总结了不同阶段的野外识别标志,初步构建了重晶石成矿的理论模型。

酒钢肃南宏兴矿业铜尾矿中有价元素回收试验研究

酒钢肃南宏兴矿业铜矿石中伴生有价元素Fe、Ba,Fe主要以菱铁矿的形式赋存、Ba以重晶石的形式赋存,浮选选铜后有价元素Fe、Ba富集于尾矿中。试验确定铜尾矿有价元素回收工艺为强磁选-悬浮焙烧-磨矿-弱磁选回收铁精矿,强磁选尾矿浮选回收重晶石。采用此工艺,在铜浮选尾矿含Fe 10.8%、BaO 4.7%的情况下,试验回收铁精矿含Fe 56.4%,回收重晶石含BaSO 488.79%。由于Fe回收只需新建强磁选和脱水工序,强磁选回收铁矿粉进酒钢选矿厂现有悬浮磁化焙烧选别系统即可,投资小、易实施。

新疆乌恰县沙热拉重晶石矿地质特征及矿床成因浅析

本文主要通过对沙热拉重晶石矿床地质特征和矿石特征的分析研究,探讨了重晶石矿床成因,总结了找矿标志。沙热拉重晶石矿床赋存于中泥盆统托格买提组,属低温热液脉型矿床。地层、构造控矿作用明显,中泥盆统托格买提组地层,断裂、破碎带等可作为找矿标志,对今后区域上同类矿床的找矿工作具有一定的指导意义。

贵州某钡渣酸浸渣浮选实验

这是一篇矿物加工工程领域的论文。钡渣为有毒固废,大量钡渣堆存严重危害环境且对国土资源造成巨大浪费。酸性浸出钡渣中酸溶钡是钡渣无害处理及回收钡最佳途径之一。论文采用浮选工艺回收富集钡渣酸浸尾渣中硫酸钡,以期实现综合回收钡渣中钡资源。浮选回收钡渣酸浸渣实验研究,在碳酸钠用量2000 g/t,硅酸钠用量500 g/t以及油酸钠用量3000 g/t的条件下,通过一次粗选、四次精选、两次扫选的浮选闭路流程,获得重晶石精矿品位85.38%、回收率69.35%的浮选指标,精矿产品达到工业生产碳酸钡用料重晶石标准。

新疆某尾矿中重晶石的回收试验

为高效回收新疆某尾矿中的重晶石,在进行了试样性质分析的基础上,采用重—磁联合工艺开展了详细的选矿试验研究。结果表明,①试样的BaSO_(4)品位为34.85%,主要脉石矿物为方解石、石英、长石及赤褐铁矿等;BaSO_(4)主要富集于-200μm粒级。②试样在筛出+200μm粒级的情况下,200~74μm粒级采用细砂摇床1粗1精重选流程处理,-74μm粒级采用矿泥摇床粗选+中矿再选闭路流程处理,重选精矿采用1次弱磁选+1次高梯度强磁选流程除铁,最终获得BaSO_(4)品位为90.65%、回收率为71.35%的重晶石精矿,精矿达到了化工用重晶石一等品品质要求,可实现该尾矿资源的综合利用。

高密度废钻井液中重晶石回收工艺综述

重晶石作为国内外油气田钻井液的主要加重剂之一,在使用过程中存在资源过量消耗、回收较为困难、回收品质不高等问题。文章针对我国油气田井场废钻井液中重晶石资源回收现状及回收难点进行剖析,对当前废钻井液中重晶石回收工艺方法及应用进行概述,阐述了多重离心机组合回收法及浮选法回收废钻井液中重晶石的工艺优势及劣势。在此基础上,提出了废钻井液中重晶石回收需结合浮选工艺以弥补固控设备分离效果的局限性等发展建议。指出未来我国需加强组合浮选药剂的开发,并充分研究药剂之间协同作用机理,在兼顾环保、经济、高效性的同时,对包括低品位重晶石及废钻井液中重晶石的回收进行指导。

重晶石防辐射混凝土基本力学性能与预测方法研究

作为降低射线危害的有效屏蔽材料,重晶石防辐射混凝土在核医学建设工程中应用广泛。为研究重晶石防辐射混凝土的基本力学性能,对影响其力学性能的因素进行研究,并基于现有试验数据对密度晶石防辐射混凝土与普通混凝土力学性能的差异,进而对典型规范预测式的适用性进行评述并修正。研究结果表明:重晶石防辐射混凝土的抗压强度与水灰比近似符合Bolomy式,掺入阴极射线管废玻璃细骨料对重晶石防辐射混凝土基本力学性能有提升作用;与普通混凝土相比,重晶石防辐射混凝土的抗压强度、劈裂抗拉强度、轴心抗压强度与弹性模量分别降低13.6%、26%、32%和37.3%;ACI 318规范可有效预测重晶石防辐射混凝土的早期抗压强度,但低估弹性模量;EC 2规范可有效预测重晶石防辐射混凝土弹性模量,但低估劈裂抗拉强度;采用修正后的ACI 318、EC 2规范模型计算方法,可有效预测重晶石防辐射混凝土各项力学性能。

含重晶石粉回填料提升地埋管换热能力研究

为研究含重晶石粉回填料对平原区第四系和山区岩石地层钻孔地埋管换热能力的影响,开展了导热系数测试实验比对分析、现场热响应实验和长期运行条件的模拟计算。平原区第四系钻孔采用中砂回填,山区基岩钻孔采用水泥砂浆回填。室内导热系数测试发现:中砂回填料中重晶石粉质量分数为5%时,导热系数提升14.3%;水泥砂浆中添加5%的重晶石粉,导热系数提升7.3%。钻孔现场热响应测试发现:同一场地内夏季工况下,平原区含5%重晶石粉回填料钻孔地埋管延米换热量提高2.4 W/m,换热效率提升3.5%;山区内含5%重晶石粉水泥砂浆回填料钻孔地埋管延米换热量提高2.7 W/m,换热效率提升3.9%。经数值模拟计算,钻孔回填料重晶石粉质量分数提升至10%,地埋管延米换热能力提高约6.0%。总体上添加重晶石粉后地埋管换热能力得到提高且可持续性较好。

安徽朱顶重晶石矿地质特征及成因浅析

安徽朱顶重晶石矿床产于郯庐主干断裂之北西向次级断裂破碎带中,赋矿围岩为上白垩统新庄组砾岩和五河群西堌堆组变粒岩,矿体呈透镜状、脉状产出,主矿体延伸稳定,围岩蚀变主要为重晶石化、硅化。矿石质量较好,品位变化属于均匀型。通过对本区矿床地质特征、矿床成因分析,认为朱顶重晶石矿主要受北西向断裂构造控制,郯庐断裂的多期活动为矿床的形成和储存提供了良好的条件,该矿床为低温热液型矿床。