An Efficient Outlier Detection Approach on Weighted Data Stream Based on Minimal Rare Pattern Mining

The distance-based outlier detection method detects the implied outliers by calculating the distance of the points in the dataset, but the computational complexity is particularly high when processing multidimensional datasets. In addition, the traditional outlier detection method does not consider the frequency of subsets occurrence, thus, the detected outliers do not fit the definition of outliers (i.e., rarely appearing). The pattern mining-based outlier detection approaches have solved this problem, but the importance of each pattern is not taken into account in outlier detection process, so the detected outliers cannot truly reflect some actual situation. Aimed at these problems, a two-phase minimal weighted rare pattern mining-based outlier detection approach, called MWRPM-Outlier, is proposed to effectively detect outliers on the weight data stream. In particular, a method called MWRPM is proposed in the pattern mining phase to fast mine the minimal weighted rare patterns, and then two deviation factors are defined in outlier detection phase to measure the abnormal degree of each transaction on the weight data stream. Experimental results show that the proposed MWRPM-Outlier approach has excellent performance in outlier detection and MWRPM approach outperforms in weighted rare pattern mining.

Recovery of Rare Earth Elements Present in Mining Tails, by Leaching with Nitric and Hydrochloric Solutions

The rare earth elements (REE) include the group of 15 lanthanides, scandium and yttrium and have diverse applications in technological and nuclear areas. The existence of REE in massive solid mining wastes generated in leaching processes of copper minerals in the Atacama region of Chile generates the possibility of creating added value to the treatment of this type of waste and supporting the development of a circular economy, generating a useful by-product in different industries. In order to know the behavior of these elements present in the solid carrier waste, a leaching process was carried out by using two agents separately, corresponding to hydrochloric and nitric acid. The technical feasibility to recover REE from carrier tail was demonstrated, the best leaching agent for these elements being a hydrochloric solution, obtaining a maximum recovery efficiency of 64.5%, for an acid concentration: 3M, temperature: 40°C and (liquid/solid) ratio: 4. Lanthanum and cerium present the best individual recoveries compared to the other REE, with a maximum efficiency for a hydrochloric solution of 75.7% and 70.0%, respectively. The interaction of operational parameters that most influence the REE recovery corresponds to the temperature and the (liquid/solid) ratio. After 4 hours of leaching, REE recovery efficiencies remain practically constant. Acid consumptions correspond to 11 (kg HCl/ton mining tail) and 29 (kg HNO3/ton mining tail). The highest amount recovery ratios of these elements correspond to 0.355 and 0.224 (kg REE/ton mining tail), for hydrochloric and nitric solutions, respectively. These results influence the types of reagents and parameters to be studied in the following stages of the global process.

China released 2017 first batch of rare earth mining quotas

China's Ministry of Land and Resources released the first batch of rare earth mining quotas in 2017, according to an announcement on the ministry's website. The total mining amount for the first batch is 52,500 tonnes, equal to the number in 2016. Out of the 52,500 tonnes, there are 43,550 tonnes for light rare earths and 8,950 tonnes for medium and heavy rare earths.

Total production quota of rare earth mining, smelting and separation in 2021

The total production quota of rare earth mining,smelting and separation in 2021 were 168,000 tons and 162,000 tons,respectively,according to the announcement released by the Ministry of Industry and Information Technology and the Ministry of Natural Resources on September 30,2021.The mining quota included 148,850 tons of rock-type rare earth ore(mainly light rare earths)and 19,150 tons of ionic rare earth ore(mainly medium and heavy rare earths).Compared with that of last year,the total quotas of rare earth mining and smelting separation were increased by 20%from 140,000 tons and 135,000 tons,respectively in 2020.

Geochemical and petrological studies of high sulfur coal and overburden from Makum coalfield (Northeast India) towards understanding and mitigation of acid mine drainage

Opencast coal mining produces trash of soil and rock containing various minerals,that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage(AMD)through oxidation pyrite minerals.The current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of India.In order to have a comprehensive overview of the AMD problem in Makum coalfield,the physico-chemical,geochemical,and petrological characteristics of the coal and overburden(OB)samples collected from the Makum coalfield(Northeast India)were thoroughly investigated.The maceral compositions reveal that coal features all three groups of macerals(liptinite,vitrinite,and inertinite),with a high concentration of liptinite indicating the coal of perhydrous,thereby rendering it more reactive.Pyrite(FeS_(2))oxidation kinetics were studied by conducting the aqueous leaching experiments of coal and(OB)samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods,and to replicate the actual mine site leaching.Inductively coupled plasma-optical emission spectroscopy(ICP-OES)was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching experiment.The Rare earth element(REE)enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and OB.These experiments reveal the change in conductivity,acid producing tendency,total dissolved solid(TDS),total Iron(Fe)and dissolved Sulfate(SO_(4)^(2−))ions on progress of the leaching experiments.Moreover,the discharge of FeS_(2) via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order kinetics.A bio-remediative strategies is also reported in this paper to mitigate AMD water by employing size-segregated powdered limestone and water hyacinth plant in an indigenously developed site-specific prototype station.Apart from neutralisation of AMD water,this eco-friendly AMD remediation strategy demonstrates a reduction in PHEs concentrations in the treated AMD water.

Remediation of in-situ Leach Mining Contaminated Soil by Amendment-plant Synergism

This study aimed to remediate in-situ leach mining contaminated soil by amendment-plant synergism. The results showed that plant species exhibited ex-tremely significant effects on the concentration of nitrate nitrogen; to be specific, the concentration of nitrate nitrogen in soil planted with wheat was reduced from 692.19 mg/kg to lower than 100 mg/kg; when the mass ratio of amendment to soil reached 3：50 and the amendment particle size was 1-2 mm, the concentration of nitrate ni-trogen in soil planted with wheat was reduced to 43 mg/kg. The amendment type exhibited extremely significant effects on the concentration of ammonium nitrogen; to be specific, when the mass ratio of amendment to soil reached 10：50, the concen-tration of ammonium nitrogen in soil added with 2-3 mm zeolite was reduced from 23 593.75 to 3 300 mg/kg on day 15. Amendments and plants mainly exhibited desorption performance for sulfate radical in soil, and the amendment type extreme-ly significantly affected the concentration of sulfate radical; to be specific, the con-centration of sulfate radical in soil added with limestone increased from 370 mg/kg to 900 mg/kg on day 7.

Behavior of ammonium adsorption by clay mineral halloysite

Ammonium pollution becomes severe during mining of ionic rare earth-ores in southern China.As one of the main clayminerals in soils of ionic rare earth mines,halloysite plays an important role in ammonium adsorption.In this study,the saturatedadsorption capacity,factors affecting adsorption and adsorption kinetics of halloysite for ammonium were investigated.The resultsindicated that the ammonium adsorption of halloysite was saturated with1.66mg/g at303K,pH of5.6and initial ammoniumconcentration of600mg/L(about half of the actual initial in-situ leaching concentration).When the initial concentration of NH4?-N,pH values and temperatures(288K to313K)increased,the ammonium adsorption capacity of halloysite increased.The ammoniumisothermal adsorption of halloysite matched the Langmuir and Freundlich isotherms.The adsorption process of ionic rare earthmining soils for ammonium was favorable.And the adsorption process followed closely the pseudo-second kinetic equation.

Review and prospects of bioleaching in the Chinese mining industry

As the world’s second largest economy experiencing rapid economic growth,China has a huge demand for metals and energy.In recent years,China ranks first,among all the countries in the world,in the production and consumption of several metals such as copper,gold,and rare earth elements.Bioleaching,which is an approach for mining low grade and refractory ores,has been applied in industrial production,and bioleaching has made great contributions to the development of the Chinese mining industry.The exploration and application of bioleaching in China are reviewed in this study.Production and consumption trends of several metals in China over the past decade are reviewed.Technological processes at key bioleaching operations in China,such as at the Zijinshan Copper Mine and Mianhuakeng Uranium Mine,are presented.Also,the current challenges faced by bioleaching operations in China are introduced.Moreover,prospects such as efficiency improvement and environmental protection are proposed based on the current situation in the Chinese bioleaching industry.

2017 US Rare Earth Industry

Rare earths were not mined domestically in 2016. Bastnaesite, a rare-earth fluorocarbonate mineral, was previously mined as a primary product at Mountain Pass, CA, which was put on care and maintenance in the fourth quarter of 2015. The estimated value of rare-earth compounds and metals imported by the United States in 2016 was $120 million, a decrease from $160 million imported in 2015. The estimated distribution of rare earths by end use was as follows: catalysts, 55%; metallurgical applications and alloys, 15%; ceramics and glass, 10%; polishing, 10%; and other, 10%.

China raised the first half of rare earth production quotas of 2021 by nearly 30%

Raw Material Industry Department of Ministry of Industry and Information Technology announced the first batch of rare earth production quotas this year on February 19,which was 84,000 tons of mining output (including 72,510 tons of light rare earths and 11,490 tons of heavy rare earths),and 81,000 tons of rare earth smelting and separating products in 2021.It was leaped by an astounding 27 percent over the first batch quotas of 2020.China has been increasing the output quotas for rare earths in recent years.The output quota for rare earth mining and rare earth smelting separation was increased from 120,000 tons to 132,000 tons and 115,000 tons to 127,000 tons respectively,increased by 10% in 2019.In 2020,the uptick pace was slightly slower,and the output cap of rare earth mining and smelting separation was increased to 140,000 tons and 135,000 tons respectively.

Study on radiation environmental impact of exploitation and utilization of Bayan Obo rare rarth ore

Taking Bayan Obo mining area of Baotou Iron and Steel Company as a typical case,the radiation environmental impact caused by the gas effluent emission from rare earth mining was investigated and evaluated.The evaluation results show that it has caused significant impact on the surrounding residents,although still lower than the limit of personal effective dose(1 mSv/a).

伊宁矿区北区西山窑组煤中稀土元素地球化学特征

煤中稀土元素具有重要的地质环境指示作用,也是潜在的稀土矿产接替资源。在伊宁矿区北区采集了西山窑组4个主采煤层的煤样进行了煤质与稀土元素地球化学测试分析。结果表明,西山窑组煤具有低灰、低硫、高挥发分、高发热量的特点,煤灰组分以Si、Al、Ca、Mg氧化物为主;煤中稀土元素含量为4.48~36.52µg/g,低于煤层顶板(36.68~191.35µg/g),其中7^(#)、6^(-2#)煤中稀土元素含量较低,为平坦型,具有Ce负异常;6^(-1#)、5^(#)煤中稀土元素含量较高,为左倾型,具有Ce轻微负异常、δEu略小于1的特点;煤中稀土元素与中酸性岩浆岩有关,以黏土矿物吸附的形式赋存。综合分析认为西山窑组沉积时期气候干热、以氧化环境为主,水深由7^(#)煤层到5^(#)煤层变浅,陆源碎屑对煤层成分影响较大。

云南普阳煤矿新近系褐煤中稀土元素的赋存状态

目前对于褐煤中稀土元素(REY)赋存状态的研究还存在较多疑问,主要体现在两个方面:一是褐煤中REY究竟主要赋存于有机质中还是矿物质中?二是褐煤含有较多容易受到酸溶干扰的含氧官能团,在逐级化学提取实验过程中,高比例HCl提取相中的REY究竟来自于碳酸盐、磷酸盐、单硫化物等矿物还是来自于有机质?着眼于此,本文在逐级化学提取这一常规元素赋存状态研究方法的基础上,结合密度分离实验、红外光谱(FTIR)等手段,对普阳煤矿新近系褐煤中REY的赋存状态进行了系统研究。研究结果表明,普阳煤矿M2和M3煤层为极低—中灰、中高—高挥发分、中硫分褐煤,其组成矿物主要为石英、方解石、高岭石、黄铁矿。M2和M3煤层中常量元素以Al和Si为主,其REY配分模式主要为L型和N型,其中M2煤层中REY轻度富集。逐级化学提取实验结果显示M2和M3煤层中的REY主要被HCl浸取,其次被HNO3浸取,同时还有部分REY保留在残渣中,HF对煤中REY的提取率很低(一般<10%)。密度分离实验结果表明REY主要赋存于低密度组分中。红外光谱分析结果显示煤样品经HCl处理后,酚羟基、羟基等含氧官能团增多,可能是经HCl浸取后样品中与酚羟基、羟基点位结合的REY被浸出迁移所致。综合来看,普阳煤矿M2和M3煤层中的REY主要赋存于有机质中,少量赋存于硅酸盐矿物中,碳酸盐、磷酸盐、单硫化物和双硫化物也可能是部分REY的赋存载体。逐级化学提取实验过程中HCl所提取的异常高比例的REY可能主要来自于有机质。

生物冶金技术的研究现状及发展趋势

低品位矿产资源的开发利用制约着全球绿色可持续发展,生物冶金技术是实现矿物加工和有色金属冶金领域绿色可持续发展的前沿性技术,同时在矿山重金属污染场地原位修复中发挥重要作用。综述了生物冶金技术的基本概念、微生物生理特征和作用机制,以及生物冶金在硫化铜矿浸出、难处理金矿氧化预处理、铀矿浸提、稀土提取等方面的应用和研究现状,提出未来应针对高效浸出微生物选育、生物浸出界面作用机制、高效节能装置和工程化技术等方面开展研究,并进一步拓展生物冶金技术研究及应用领域。

四川大陆槽稀土尾矿回收萤石实验

这是一篇矿物加工工程领域的文章。本文以德昌大陆槽稀土选矿尾矿为研究对象,开展了萤石回收的选矿实验研究,确定了该尾矿中萤石回收的“浮选脱硫-混合浮选-萤石、锶钡浮选分离”选矿工艺流程和药剂制度,在浮选实验中使用了新型捕收剂MQY与高效抑制剂DC-2,在对萤石高效捕收的同时实现了萤石与脉石矿物的精准分离,最终全流程实验获得了CaF_(2)品位94.39%,回收率51.41%的萤石精矿,实验指标较为理想。本文验证了从大陆槽稀土尾矿中回收萤石具有较好的可行性,最终确定的选矿工艺流程较为合理,实验指标较为良好,可作为大陆槽稀土尾矿中萤石资源利用回收的技术依据。

离子吸附型稀土矿电动开采技术初探

离子吸附型稀土矿是我国的特色资源,为全世界提供了90%以上的中、重稀土。然而,现有的离子吸附型稀土矿中铵盐原地浸出开采工艺存在环境污染严重、资源利用率低、开采周期长和滑坡地质灾害频发等问题,开发新一代高效绿色的离子吸附型稀土矿提取技术是国家稀土战略的紧迫需求。本文介绍了电动开采离子吸附型稀土矿的概念设想,并对电动技术的特点进行了初步探索。通过实验室土柱实验证实了电动开采离子吸附型稀土矿的可行性,结果表明:电动法稀土采收率高,约为同等条件下传统直接浸出方法的2倍。电动开采过程中,电压梯度对稀土回收有重要影响:电压梯度升高,稀土元素浸出速率提高,但同时电解强烈,导致阴极附近稀土元素沉淀含量增加,浸出液中稀土元素含量降低。其次,电动开采过程必须添加提取剂,提取剂起到增加体系导电性和交换解吸风化壳中稀土离子的作用。最后,结合电动过程阳极由于电解产生H^(+)的特点,本文还提出了采用碳酸钙作为复合提取剂成分的设想,起到了有效缓解土壤pH值变化,并释放钙盐的作用。

CaO-SiO_(2)-La_(2)O_(3)体系中最佳稀土富集相的在线分离与表征

内蒙古白云鄂博矿是世界上最大的铁-铌-稀土多金属共伴生矿床,稀土远景储量位居世界第一。在该矿床开采过程中,稀土等有价元素未能得到有效的提取而进入渣中,形成重要的稀土二次资源。为了回收其中的稀土资源,基于白云鄂博冶金矿渣主组元,以CaO-SiO_(2)-La_(2)O_(3)三元基础体系为研究对象,首先明确了该体系的最佳稀土富集相为Ca_(x)La_(4.67-x)(SiO_(4))3O_(1-0.5 x)相。随后引入超重力场,在G=1000、时间10 min、温度1350℃的条件下对Ca_(x)La_(4.67-x)(SiO_(4))3O_(1-0.5 x)稀土相与渣相进行在线分离,得到了高纯稀土相晶体。最后对得到的稀土晶体进行结构表征和Rietveld精修,明确了其具体化学式为Ca_(1.11)La_(3.56)Si_(3)O_(12.36),并获得了该稀土相的晶体结构、晶体数据等信息,进一步完善了稀土相的基础物理化学数据,为稀土资源的回收利用提供了理论依据。

赣南稀土尾矿山土体硝态氮累积特征研究

稀土开采会造成大量浸矿剂(硫酸铵)残留在土壤中,高浓度铵态氮(NH_(4)^(+)-N)可能在生物化学作用下转化为硝态氮(NO_(3)^(-)-N)。为探明NO_(3)^(-)-N在稀土尾矿山土体内的含量及影响因素,明确硝酸盐污染程度,本研究选择赣南地区一个离子型稀土原地浸矿尾矿山,由表土分层采样至基岩面,并分析土壤NO_(3)^(-)-N及相关的理化性质。研究结果表明,尾矿山土体NO_(3)^(-)-N含量变异范围非常大(2.80~193.99 mg·kg^(–1)),其平均值为46.30±55.16 mg·kg^(–1),表层土壤NO_(3)^(-)-N含量范围为2.89~6.75 mg·kg^(–1),与自然土壤相近;表层以下土壤NO_(3)^(-)-N含量明显高于自然土壤。尾矿山土体深部含矿层土壤NO_(3)^(-)-N含量明显高于表层,NO_(3)^(-)-N含量随深度的分布规律与自然土壤相反,这是矿体部分残留大量浸矿剂造成的。土壤NH_(4)^(+)-N含量主导了NO_(3)^(-)-N的产生量,但NO_(3)^(-)-N在土体不同深度、山体不同部位的累积量还受降雨淋溶及NO_(3)^(-)-N迁移过程的控制。开采结束4年后,尾矿山内累积的NO_(3)^(-)-N仍不断向环境中释放。长期来看,尾矿山土壤中富集的NH_(4)^(+)-N将不断转化为NO_(3)^(-)-N并随水迁移,持续威胁生态环境及人类健康。本研究可为稀土原地浸矿场地土壤及下游水体污染的评价和治理提供理论基础与科学支撑。

氮添加对稀土尾砂地猴樟幼苗根系生长、生物量分配及非结构性碳水化合物的影响

为探究氮添加对稀土矿尾砂地猴樟(Cinnamomun bodinieri)幼苗生长及非结构性碳水化合物(NSC)含量的影响,以1年生猴樟扦插苗为研究对象,选用硝酸铵钙作为氮肥(含N 15%),设置3种氮肥水平(CK(0)、N1(1.8 g·株^(-1))、N2(3.6 g·株^(-1))),分析不同氮添加水平下猴樟幼苗根系生长、生物量分配和NSC等指标的差异,探讨稀土尾砂地猴樟对氮添加的响应。结果发现:稀土尾砂地氮添加均增加了猴樟幼苗不同组织的生物量积累,其中N1处理下叶生物量、冠层生物量分别较N2处理下显著提升了44.75%、57.43%(P<0.05);N2处理下叶比重分别较CK、N1处理显著提升了123.53%、15.85%(P<0.05)。不论是粗根(直径>2 mm),还是细根(直径≤2 mm),氮添加均显著增加了植物的根长和根表面积(P<0.05),其中N1处理的促进效果最显著(P<0.05);N2处理下的比根长、比表面积均高于CK与N1,且与CK显著差异(P<0.05)。对NSC来说,N1处理提升了叶、茎中的可溶性糖质量分数,而N2处理下细根NSC质量分数分别比CK、N1显著降低了46.49%、28.61%。综上,在稀土矿尾砂地植被恢复过程中,宜选用1.8 g·株^(-1)硝酸铵钙氮肥对猴樟幼苗进行施肥管理。