Mineralogical and geochemical alteration of Hitura sulphide mine tailings with emphasis on nickel mobility and retention

Weathering of Hitura (W Finland) nickel sulphide mine tailings and release of heavy metals into pore water was studied with mineralogical (optical and electron microscopy, X-ray diffraction) and geochemical methods (selective extractions). Tailings were composed largely of serpentine, micas and amphiboles with only minor carbonates and sulphides. Sulphides, especially pyrrhotite, have oxidized intensively in the shallow tailings in 10–15 years, but a majority of the tailings have remained unchanged. Oxidation has resulted in depletion of carbonates, slightly decreased pH, and heavy metal (Ni, Zn) release in pore water as well as in the precipitation of secondary Fe precipitates. Nevertheless, in the middle of the tailings area, where the oxidation front moves primarily downward, released heavy metals have been adsorbed and immobilized with these precipitates deeper in the oxidation zone. In contrast to what was seen in pore water pH, but in accordance with static tests of the previous studies, the neutralisation potential ratio (NPR) calculated based on the mineralogical composition and the total sulphur content suggested that tailings are ‘not potentially acid mine drainage (AMD) generating’. However, the calculated buffering capacity of the tailings resulted largely from the abundant serpentine because of the low carbonate content. Despite its slow weathering rate, serpentine may buffer the acidity to some extent through ion exchange processes in fine ground tailings. Nevertheless, in practice, acid production capacity of the tailings depends primarily on the balance between Ca–Mg carbonates and iron sulphides. NPR calculation based on carbonate and sulphur contents suggested, that the Hitura tailings are ‘likely AMD generating’. The study shows that sulphide oxidation can be significant in mobilisation of heavy metals even in apparently non-acid producing, low sulphide tailings. Therefore, prevention of oxygen diffusion into tailings is also essential in this type of sulphide tailings.     

Otolith chemical signature and growth of Chaetodon speculum in coastal areas of New Caledonia

Coral reefs are one of the most diverse ecosystems on Earth. They are currently exposed to increasing levels of anthropogenic perturbations. Several recent reviews point to the lack of good indicators for these perturbations especially to monitor their effects on fish populations or fish assemblages. The SW lagoon of New Caledonia is an ideal location to test indicator species in this context as contrasting sites are present within a small geographical range. This study analysed fish from four sites, one with heavy industrial pollution, another dominated by domestic waste, a third with historic mining activities, and the fourth as a control. The butterfly fish, Chaetodon speculum, was chosen to determine C. speculum's potential as an indicator species due to its link to coral, its sedentary behaviour and its wide geographical distribution. The size distribution, growth rate, age distribution and whole otolith composition were analysed at each site. Age and mean growth rate were analysed from daily increments of the otoliths. The concentrations of eight elements (Li, Mg, Co, Ni, Cu, Rb, Sr, and Ba) were measured by ICP-MS in the otoliths of a subset of individuals. The sites under anthropogenic impact were distinct from the control site by fish size frequencies, age distributions, and the chemical content of their otoliths. The chemical elements Mg, Co, Ni, Cu, and Rb showed differences amongst sites. Fish belonging to the sites furthest from Nouméa could be discriminated in nearly 80% of samples or 60% of the cases when otolith weight or fish age respectively were taken into account. Ni concentrations of the otoliths were also higher in the bays where water concentrations of this element were known to be higher, but these differences were no longer significant once corrected for otolith weight. These results should be mitigated by the fact that: (1) despite significant differences between sites in age distribution and size frequencies there were no differences in growth rates or body condition; (2) differences in age or size were not correlated to perturbation levels; and (3) discrimination between sites based on chemical levels in the otoliths, even though significant, was not sufficient to identify the origin of the fish at a level useful for screening tests. The hypothesis that environmental differences between sites would be reflected in the otolith chemical composition is therefore not fully supported by our results.     

大倾角煤层分层综采再生顶板破断规律研究

针对大倾角厚软煤层下分层安全综采问题,结合淮南矿区潘北煤矿1212（3）大倾角厚软煤层分层综采下分层工作面地质与工程条件,综合运用基于数字散斑、声发射监测与分布式光纤传感技术的物理模拟试验、基于煤系地层赋存禀赋建模技术的数值模拟试验相结合的研究手段,开展了下分层开采再生顶板破断倾向分区演化、再生岩体变形声发射能量与光纤应变响应规律及应力分布特征研究。结果表明：再生顶板破断由其破断岩块滑移、低中位悬臂梁和高位铰接岩梁断裂组成,双梁破断是引起下分层支架失稳的关键所在。下分层中上部双梁破断声发射能量呈高度聚集且持续时间短,光纤感知低位悬臂梁破断且中上部光纤应变峰值高,下分层中上部是支架与再生顶板稳定性控制的重点区域。下分层下部再生顶板破断岩块充填密实且粒径小,是架间与架前岩块漏冒多发区域。下分层再生顶板中形成高应力组成的应力拱,距采空区高度约30 m,双梁破断主要发生在拱内,拱中岩体破断对支架具有一定的冲垮作用。     

EXPERIMENTAL AND FIELD STUDY ON MINING-PIT MIGRATION

1 INTRODUCTION Because of the large quantity of sand and gravel in their beds, rivers have always been considered as a major source of sand and gravel for civil works. Acceptable quality, ease of extraction and economy are some of the reasons could be mentioned. Unfortunately, specific laws and regulations regarding the safe in-stream mining have not been provided for users and officials. What should be taken into account are the effects of over-mining of sand and gravel, which can cause …     

中国开辟区不利开采地形类型及其分布

利用1998年"大洋一号"调查船近海底作业所获的深拖海底电视和照相系统资料,对中国开辟区不利开采地形类型及其分布特征进行了研究,并对海底地形的坡度进行了计算,结果表明:(1)中国开辟区东、西两区海底的东向坡和西向坡是均衡分布的。东、西两区海底地形坡度的分布特征明显不同,东区海底地形坡度以0～15°为主,而西区坡度大于3°的地形则很少。坡度大于5°的地形主要分布于坡脚处,特别是坡度超过15°的地形总是出现在水深变化的转折点处。(2)研究区不利开采地形可分为坡度为5～15°和大于15°两种类型,东区地形坡度大于5°的不利开采地形比西区多14%,东区坡度大于15°的地形为3.6%,比西区(仅为1.4%)多,东、西两区都有少量坡度近90°的地形出现,并且这种地形在东区所占比率比西区大,说明东区断崖、陡坎和断裂沟槽比西区多,地形也更为复杂多变。     

煤炭国家规划矿区管理及与煤炭矿区辨析

针对煤炭国家规划矿区与煤炭矿区易混淆不清问题,基于相关标准和通知,详细解读了煤炭国家规划矿区和煤炭矿区的定义,梳理了第一、二批煤炭国家规划矿区和《全国矿产资源规划（2016-2020年）》划定的煤炭国家规划矿区基本情况,并从划定目的、划定依据和形成时段等方面详细阐述了二者的区别。指明煤炭国家规划矿区划定主管部门是自然资源部,划定主要目的是控制矿权设置,规范矿业权管理;煤炭矿区划定主管部门是国家发展改革委,划定目的主要是为生产开发做准备。在未来煤炭国家规划矿区管理工作中,建议加强煤炭规划矿区基本理论、划定标准及规划矿区内矿产资源与环境影响等方面的研究。     

Coal mining along the Warfield Fault, Mingo County, West Virginia: a tale of ups and downs

Mine development along a 15-mile (24 km) section of the Warfield Fault in Mingo County, West Virginia has broadened the geological understanding of the fault and its related structures. The fault has been exposed in two new road cuts, one in the northeast-trending segment at Neely Branch and one in the eastern east-trending segment at the head of Marrowbone Creek. Both exposures show a well-defined normal fault with a 45° to 55° N dip, juxtaposing sandstone/shale packages from the roof and the floor of the Coalburg seam. The fault is associated with a thin gouge zone, some drag folding, and parallel jointing. Its trace tends to run parallel to the crest of the adjacent Warfield Anticline. Based on underground mine development and detailed core drilling, the vertical offset along the fault plane ranges from a maximum of 240 ft (73 m) in the central part of the area near the structural bend to less than 100 ft (30 m) in western and eastern directions. The fault is located along the relatively steeply dipping (locally in excess of 25%) southern limb of the Warfield Anticline, and appears related to a late phase of extension involving folded Pennsylvanian strata. On a regional scale, the lithological variations across the fault do not suggest any appreciable strike-slip component.Underground room and pillar mines in the Coalburg seam north and south of the fault have been greatly impacted by the Warfield structures. Due to the combined (and opposite) effects of the folding and faulting, the northern mines are located up to 400 ft (125 m) higher in elevation than the southern ones. Overland conveyor belts connect mining blocks separated by the fault. The practical mining limit along the steep slopes toward the fault is around 15%. Subsidiary normal faults with offsets in the 5- to 15-ft (1.5–4.5 m) range are fairly common and form major roof control and production hurdles. Overall, the Warfield structures pose an extra challenge to mine development in this part of the Appalachian Coalfields.     

论船舶物权变动登记之公信力

船舶物权变动采用登记公示方式,登记应当具有公信力,登记公信力制度的确立旨在保护第三人之利益。登记是制度创设,应该承认船舶登记的公信力以满足该制度之宗旨。船舶登记的对抗效力不影响登记公信力的存在,但该登记的公信力受到限制。     

K-means算法复杂度的能量分析方法

传统的算法复杂度分析方法重点对算法的内在流程进行分析,而且对于数据挖掘时具有很大不确定性,执行时间不能准确确定.用物理学原理从能量的角度对数据挖掘中的经典聚类算法K-means进行分析,并从算法的本质上推导出其复杂度下限,推导出该算法能优化到的极限值.     

肥城市采煤塌陷区治理模式探索研究

肥城煤田作为国家重要能源基地,开发历史悠久,为我国高速发展的国民经济做出了巨大贡献。但长期开采导致塌陷范围广、深度大、积水严重,生态环境遭受严重破坏,给矿区群众的生产生活带来严重影响。该文总结了目前普及化程度较高的采煤塌陷区治理模式,以此为基础,对肥城市采煤塌陷区按照因地制宜的原则,通过分析研究、归纳得出适应于肥城市采煤塌陷区四种不同的治理模式,分别为:土地复垦治理模式、“渔业+农业”治理模式、生态修复治理模式、综合治理模式,并对四种治理模式进行了阐述分析,对今后肥城市采煤塌陷区治理起到借鉴和指导作用。