Rheological properties and concentration evolution of thickened tailings under the coupling effect of compression and shear

Cemented paste backfill(CPB)is a key technology for green mining in metal mines,in which tailings thickening comprises the primary link of CPB technology.However,difficult flocculation and substandard concentrations of thickened tailings often occur.The rheological properties and concentration evolution in the thickened tailings remain unclear.Moreover,traditional indoor thickening experiments have yet to quantitatively characterize their rheological properties.An experiment of flocculation condition optimization based on the Box-Behnken design(BBD)was performed in the study,and the two response values were investigated:concentration and the mean weighted chord length(MWCL)of flocs.Thus,optimal flocculation conditions were obtained.In addition,the rheological properties and concentration evolution of different flocculant dosages and ultrafine tailing contents under shear,compression,and compression-shear coupling experimental conditions were tested and compared.The results show that the shear yield stress under compression and compression-shear coupling increases with the growth of compressive yield stress,while the shear yield stress increases slightly under shear.The order of shear yield stress from low to high under different thickening conditions is shear,compression,and compression-shear coupling.Under compression and compression-shear coupling,the concentration first rapidly increases with the growth of compressive yield stress and then slowly increases,while concentration increases slightly under shear.The order of concentration from low to high under different thickening conditions is shear,compression,and compression-shear coupling.Finally,the evolution mechanism of the flocs and drainage channels during the thickening of the thickened tailings under different experimental conditions was revealed.

THE RESEARCH OF RHEOLOGICAL PROPERTIES OF STOWING SLURRY WITH HIGH-WATER MATERIALSOLIDIFYING TAILINGS

High-water material, tailings from goldmine and water are mixed into a new slurry.Testing of rheological properties of stowing slurries A and B is made to determine type and rheological parameters of the slurry. The main factors influencing rheological properties of the slurry are analyzed and the rational concentration and empirical resistance calculating formula of pipe line transportation are presented.

Fe extraction from high-silicon and aluminum cyanide tailings by pretreatment of water leaching before magnetic separation

Pretreatment of high content of Si- and Al-containing cyanide tailings by water leaching to remove some impurities, such as the major impurities minerals of Si and A1, as well as its effect on Fe extraction in the water leaching process was investigated. The effects of different parameters on iron recovery were studied, and the reaction parameters were proposed as follows： sodium carbonate content of 30%, water leaching at 60 ~C for 5 min, liquid/solid ratio of 15：1, and exciting current of 2 A. Under these optimal conditions, magnetic concentrate containing 59.11% total iron and a total iron recovery rate of 76.12% was obtained. In addition, the microstructure and phase transformation of the process of water leaching were studied by X-ray powder diffraction technique （XRD）, Electronic image of backscattering （BEI）, X-ray fluorescence （XRF）, and energy dispersive spectrometry （EDS）. The results indicate that the soluble compound impurities generated in the roasting process are washed out, and the dissoluble substances enter into nonmagnetic materials by water leaching, realizing the effective separation of impurities and Fe.

Secondary Recovery of Columbite from Tailing Dump in Nigerian Jos Mines Field

Millions of tons of tailing dump at Rayfield mine in Jos in North Central Plateau state of Nigeria have been found to contain large quantity of columbite. Initial attempts to recover columbite concentrates by local miners and mineral speculators from the columbite rich tailing dump failed due to the ineffective processing route employed. Using cone and quartering sampling method, 0.5 kg of the columbite tailing was obtained for sieve and chemical analyses. 50 kg of <1mm fraction of the sample was subjected to a first stage magnetic concentration in a three poles Dry High Intensity Magnetic Separator (DHMS) that separated the columbite in the third pole. The re-grind of the + 0.355 mm rougher concentrate fraction (containing interlocking columbite) to pass the sieve aperture was treated on the DHMS in the second stage. The rougher concentrate undersize and columbite pre-concentrate of the first stage magnetic separation were then gravity concentrated on the air float machine. The Rayfield tailings and final concentrate were assayed using ED-XRFS to obtain 12.5% and 69.6% Nb2O5, respectively. The recovery and separation efficiency were 77.95% and 77.88% in that order. The magnetic and gravity concentrations were found effective at 77.95% recovery for columbite from the Rayfield tailing dump. This study also provided database for optimum recovery of columbite from tailings of mining sites of similar composition.

Possible Synergistic Toxicity of Oxygen Scavenger and Defoamer on the Niger Delta Freshwater <i>Tilapia guineensis</i>

Globally, the generation of produced water keeps increasing due to depleting wells and about 40% of this wastewater is disposed of into the environment. Produced water is made up of several components that are toxic in nature, like production chemicals that are used for oil and gas production activities. Oxygen scavenger and defoamer are commonly used for corrosion prevention as both are applied at different stages of corrosion prevention. Evaluation of the possible synergistic toxicity contribution of oxygen scavenger and defoamer formed the basis of this research and was conducted using the Tilapia guineensis as bio-indicator. The toxicity test was carried out using the ELIMINOX (oxygen scavenger) and EC9017A (defoamer) individually and both chemicals were combined together. The choice of these chemicals was premised on previous researches that have confirmed that they are toxic individually, without further research on how they interact when they are combined. These chemicals and freshwater were used to generate produced water samples in the laboratory. The experiment was set up by adding ten fishes into each of the glass containers, containing the produced water samples at different concentrations and a control sample without the chemicals. The rate of mortality of the fish for the individual chemicals ranged from 100% to 10% for the different percentage concentrations. While on the other hand, a combination of the two chemicals had more survival than mortality, the percentage survival rate ranged from 100% to 90% across all the percentage concentrations. The lethal concentration also showed that the oxygen scavenger was more toxic than the defoamer, however, when they were combined;they showed an antagonistic relationship as the toxicity of the oxygen scavenger drastically reduced. The research findings intend to create awareness of the possible interaction of production chemicals when they are used for oil and gas activities and their combined toxicity contribution to produced water. This will in turn aid government regulators in their decision-making for disposal of produced water.

Cemented backfilling technology with unclassified tailings based on vertical sand silo

A new technology characterized by rapidly non-mechanical settlement of unclassified tailings was developed based on a large number of tests, and dynamic settlement and continual slurry preparation without hardening in vertical sand silo were eventually realized by the addition of an effective flocculating agent (NPA). The results show that the sedimentation velocity of interface between unclassified tailings and water after the addition of NPA increases by 10-20 times, the sedimentation mass fraction of unclassified tailings at the bottom of vertical sand silo is up to 64%, the solid particle content of waste water meets the national standard, and the side influences of NPA can be removed by the addition of fly ash. The industrial test result shows that the system, the addition manner and the equipments are rational, and the vertical sand silo is used efficiently. This developed system is simple with large throughput, and the processing cost is 2.2 yuan(RMB)/m3, only 10%-20% of that by mechanical settlement.

某选硫尾矿回收明矾石和石英试验研究

为充分有效地回收尾矿中的明矾石和石英,针对尾矿中硫含量高、SiO_(2)含量低、明矾石和地开石含量较高的特点,开展了尾矿脱硫回收明矾石和石英的试验研究。试验考察了脱硫浮选碳酸钠、油酸、水玻璃等药剂以及明矾石和石英混浮、脱硫再选工艺等对明矾石和石英回收的影响。结果表明,碳酸钠用量为3000 g/t、油酸用量为250 g/t~300 g/t、水玻璃用量为100 g/t~200 g/t、经两次粗选可得到SiO_(2)品位74.66%、TS 0.99%的尾砂,三次粗选可得SiO_(2)品位79.77%、TS0.87%的尾砂精矿;三次粗选精矿合并精选时,随着精选水玻璃用量的增加,S在精矿中得到富集。综合考虑,两次精选均为空白精选,可获得品位27.59%的明矾石精矿。

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。

大西沟某尾矿库尾矿有价组分综合回收试验研究

对陕西大西沟某铁品位15.70%的选铁尾矿开展了有价组分综合回收试验研究,采用浮选铜硫、强磁选提铁、焙烧选铁、摇床重选-浮选提取重晶石和云母工艺,获得了TFe品位60.17%(S含量0.11%)、TFe回收率66.74%的铁精矿,S品位47.86%、回收率66.58%的硫精矿,Cu品位19.79%、回收率31.24%的铜精矿,BaSO_(4)品位86.96%、回收率9.15%的重晶石粗精矿和K_(2)O品位6.66%、回收率6.63%的云母精矿,实现了尾矿分质综合利用。

锌氧压酸浸硫精矿和硫尾矿的矿物学特征与环境活性

采用电感耦合(ICP-OES)、X射线衍射(XRD)、扫面电镜-能谱(SEM-EDS)、红外光谱(FTIR)及差热差重(TG-DTA)等多种检测方法对锌氧压酸浸硫精矿和硫尾矿的化学组成、粒度分布、物相结构等进行研究,并采用毒性浸出程序(TCLP)法考察其短期环境活性。研究结果表明:硫精矿1和硫精矿2主要以球状的单质硫存在,其中,少量硫精矿1以小颗粒的闪锌矿、黄铁矿等附着于块状的铁矾颗粒上,平均粒径为22.1μm;少量硫精矿2以块状的闪锌矿、黄铁矿和小颗粒存在,平均粒径为59.2μm。2种硫精矿在185~340℃时会剧烈燃烧,热稳定性较差。2种硫尾矿主要以块状的铅黄铁矾和黄钠铁矾存在,其中,硫尾矿1平均粒径为21.1μm;硫尾矿2含一定的赤铁矿(16.86%),平均粒径为5.3μm。硫精矿和硫尾矿中锌和镉元素在弱酸条件下不稳定,硫尾矿1中锌和镉的浸出量分别超标1.93倍和2.50倍;硫精矿2的分别超标2.03倍和6.56倍,硫尾矿1的分别超标3.46倍和5.94倍,硫尾矿2的分别超标11.10倍和8.28倍。

尾矿水浸泡对砂岩结构及力学特性影响研究

尾矿水长期浸泡会对岩石稳定性造成潜在影响,可能引发一系列危害。为研究尾矿水溶液的溶蚀作用对砂岩力学性能和微观结构的影响,采用自来水和尾矿水对砂岩进行90 d浸泡,随后进行离子浓度测定和单轴压缩试验。利用扫描电镜和能谱仪对砂岩试样的微观形貌以及表面元素进行分析,建立尾矿水对岩石溶解的数值模型。研究结果表明:与天然试样相比,自来水浸泡后试样的强度和弹性模量分别降低了16.38%和18.5%,而尾矿水浸泡后其强度和弹性模量分别降低了24.42%和25.42%。尾矿水呈弱碱性,与砂岩的主要成分石英钠长石(NaAlSi_(3)O_(8))和钾长石(K(AlSi_(3)O_(8)))发生化学反应,生成大量的Na^(+)和K^(+)离子,溶液中离子浓度分别增加了40.17%和19.8%,导致砂岩表层微观结构破坏、孔隙和裂隙增大,从而使得弱化效果更加显著。研究成果为理解尾矿水对砂岩浸水弱化机理提供了有益参考,并为尾矿工程安全研究、分析、测评提供科学依据。

钼精选尾矿浮选回收铜

某矿山钼精选尾矿含铜0.526%,铜主要以黄铜矿形式存在,具有综合回收利用价值。尾矿中其它矿物主要为石英、绿泥石和黄铁矿。尾矿粒度极细,且黄铁矿含量高,铜硫分离困难。采用单因素条件试验系统研究了浮选工艺参数条件和药剂制度对铜精矿铜品位和铜回收率的影响,进一步优化工艺参数条件,并分别开展了开路和闭路浮选试验。结果表明,最佳浮选工艺参数条件和药剂用量分别为:矿浆浓度30%、水玻璃用量1000 g/t、石灰用量500 g/t、硫酸铜用量300 g/t、丁基黄药50 g/t、充气量0.2 m^(3)/h;采用一次粗选、三次精选、三次扫选(一粗三精三扫)的浮选工艺流程,最终可获得铜品位24.18%、铜回收率85.65%的铜精矿,综合浮选指标较佳,可实现钼精选尾矿中有价金属铜的高效回收。

微细粒铁尾矿浮选回收萤石工艺试验研究

某选铁尾矿细泥中含少量萤石矿物资源。基于工艺矿物学分析,本试验提出萤石磁浮联合工艺,实现了微细粒选铁尾矿中低品位萤石的高效回收。结果表明,铁尾矿-0.038 mm占比76.97%,经磁场强度636.8 kA/m强磁选可抛除42.89%磁性脉石矿物,CaF_(2)品位由13.91%提至21.04%;采用碳酸钠作为调整剂,酸化水玻璃为抑制剂,改性脂肪酸作为捕收剂进行浮选,最终获得产率为7.81%、CaF_(2)品位为90.72%、CaF_(2)回收率为50.94%的萤石精矿产品。

空气中CO_(2)原位高效捕集研究

空气中低浓度CO_(2)的高效捕集是实现“碳中和”的重要路径。采用太阳能驱动空气泵加速CO_(2)的高效捕集,选取CaO、四乙烯五胺和NaOH溶液分别进行吸收,CaO粉末的CO_(2)日累积吸收量超过0.9 g。液相捕获剂中,CO_(2)日累积吸收量随NaOH浓度的上升而增加,0.50 mol/L的NaOH溶液中CO_(2)的吸收量可达0.776 g。CO_(2)小时吸收量小时变化趋势分析得出,其与光照强度和环境温度密切相关,进而影响了通过捕获剂的空气流量和CO_(2)总量;环境温度不仅影响了捕获剂吸收CO_(2)的反应速率,同时也极大程度上影响了气体在溶液中的溶解度。固体捕获剂CaO反应前后XRD分析,说明过程中生成了CaCO3。液相吸收剂蒸干处理后结晶产物XRD分析,说明反应过程中生成了CO32-。

直升机涵道尾桨永磁同步电机设计与仿真

针对直升机涵道尾桨机械传动系统传动链长、噪声大、结构复杂、传动轴刚度差和安装维护周期长等缺陷,设计一种适用于直升机涵道尾桨的永磁同步电机。通过探究悬停工况下电机主要尺寸与尾桨桨叶长度、宽度以及安装角度的关系,明确一定范围内电机主要尺寸最小时的功率、转矩和转速;采用分数槽集中绕组进一步提升了功率密度,基于14极18槽完成了电机设计。建立电磁场和温度场有限元仿真模型,验证电磁设计的合理性以及永磁体分段降温的有效性。与未分段相比,当永磁体沿周向分4段时,永磁体平均温度降低了55.43%。结果表明:该电机功率密度较高,输出特性良好并且温升较低,能够长时间可靠运行。

智能浮选系统在下峪口选煤厂的应用

针对浮选系统自动化水平低、缺少实时生产数据、浮选精煤灰分波动大等问题,下峪口选煤厂结合自身实际情况,研发了基于模糊控制的智能浮选系统。该系统主要包括智能控制平台、智能感知系统、智能加药站等,分为数据采集层、数据层、控制逻辑层和人-机交互层。改造后,浮选系统由人工控制变为“机器智能控制+人工巡视”。生产实践表明:智能浮选系统的投运使浮选精煤灰分由9.0%~13.0%稳定至12.0%~13.0%,尾矿发热量由5.02MJ/kg左右降低至4.19MJ/kg以下,精煤产率提高了0.18个百分点,每年创造经济效益729万元。智能浮选系统的应用,稳定了产品质量,实现了降本增效,具有良好的社会效益,可为其他选煤厂浮选系统智能化改造提供有益参考。

沁新选煤厂特色浮选工艺流程的研究与应用

概述了近年来部分选煤厂煤泥浮选工艺流程的改进优化情况,详细介绍了沁新选煤厂浮选流程演进优化历程,历经一次浮选、一粗一精、一粗一扫等浮选工艺,直至形成适合沁新选煤厂易浮煤泥特性的一粗一扫+扫选精矿分段回收的现行浮选流程。生产实践表明:该浮选流程大幅节省了循环水用量;入选低硫煤时,浮选精煤灰分为7.21%,最终尾煤灰分从74.09%提高到82.51%;入选高硫煤时,浮选精煤灰分为6.78%,最终尾煤灰分从57.93%提高到82.37%;通过扫选获得了发热量为19.25MJ/kg的浮选中煤产品,日增中煤产量约200t;通过化验扫选精矿分室的产品灰分,第一室产品灰分为16.18%,低于重选边界灰分,可掺入总精煤,日增精煤产量约120t。该浮选流程具有特色,已在沁新集团下属选煤厂推广应用,取得了良好效果,为易浮煤泥高效浮选和高值利用开辟了新工艺。

某钼矿伴生极低品位铜综合回收试验研究

某钼矿伴生极低品位硫化铜,铜品位为0.016%,直接回收难度大。硫化铜天然可浮性好,部分硫化铜进入钼精选作业,钼精选作业铜钼分离后钼精扫尾矿中铜可以富集至1.78%,具有一定的经济价值。为高效回收钼精扫尾矿中的铜金属,进行了脱水不脱水对比、石灰用量(pH)、捕收剂种类和用量、再磨细度等关键试验研究。试验结果表明:采用一次粗选—两次扫选—四次精选的脱水工艺流程,当pH调整剂石灰用量为50 g/t,铜捕收剂Z200用量为28 g/t,起泡剂2#油用量为1.3 g/t时,可获得精矿品位为21.49%,作业回收率为79.41%的铜精矿。

金沙磷矿反浮选尾砂沉降浓缩试验研究

尾砂高效沉降浓缩是充填系统工艺设计的关键环节,针对金沙磷矿全尾砂粒径偏细,且含有脂肪酸类浮选药剂的物化特性,开展全尾砂自然沉降和絮凝沉降试验,以固体通量和底流浓度作为评价指标,探明了全尾砂沉降浓缩性能,确定了絮凝剂类型、尾砂浆进料浓度和絮凝剂添加量。试验结果表明:尾砂浆自然沉降过程中,极细尾砂颗粒伴随着药剂泡沫上浮,导致自然沉降速率降低,沉降界面难以观察;尾砂浆静态絮凝沉降过程中,絮凝剂最佳型号为爱森665S,最佳进料浓度为10%~14%,絮凝剂最佳添加量为20~25 g/t;尾砂浆动态絮凝沉降过程中,在进料浓度为12%,絮凝剂添加量为25 g/t,耙架转速为5 r/h时,底流浓度达到了68%。研究成果可为国内类似磷矿尾砂沉降浓缩提供参考。

氰化尾渣综合回收试验研究

辽宁某氰化尾渣金品位2.01 g/t,银品位36.23 g/t,铜、铅、锌品位分别为0.33%、1.91%、3.01%。针对该氰化尾渣进行铜铅锌混合浮选试验及优先选铅—尾矿选锌浮选试验。铜铅锌混合浮选试验可获得金品位13.72 g/t、银品位281.70 g/t、铜品位3.63%、铅品位16.01%、锌品位36.92%,金、银、铜、铅、锌回收率分别为50.09%、57.22%、80.69%、61.33%、90.88%的混合精矿;优先选铅—尾矿选锌浮选试验可获得铅品位48.95%、铅回收率52.29%的铅精矿,锌品位43.21%、锌回收率89.45%的锌精矿,铅精矿中金、银、铜品位分别为54.02 g/t、891.42 g/t、5.92%,锌精矿中金、银、铜品位分别为2.43 g/t、134.79 g/t、2.19%,总金、总银、总铜回收率分别为62.39%、73.43%、77.76%。选别指标良好,为该类氰化尾渣资源的综合回收利用提供了参考依据。