Development and implementation of spin to stall resin at Anglo Americans Australian underground coal operations

Longwall mining is by far the most common method of underground coal extraction in Australia. The industry trends and expectations are placing increasing emphasis on the reliability and productivity of these operations. The longwalls are becoming wider and longer while retreat rates are continuously increasing due to significant improvements achieved in longwall equipment reliability and automation.This increased longwall productivity is placing significant emphasis on the reliability of longwall panel development. Although there have been significant improvements in the reliability of continuous miners and hydraulic drill rigs,the traditional resin encapsulated bolt installation is still the principal method used in all major coal-producing countries around the world. Anglo American realised an opportunity existed to introduce an alternative roof bolt installation technique called ‘‘spin to stall" in Australia.Spin to stall was first introduced in Anglo American Coal in South Africa where it has been successfully used for over a decade,though implementation of South African spin to stall resin in Australia has proven to be near impossible due to a significant difference in geotechnical conditions,mining method,and,subsequently,roof bolting equipment. Therefore,a new spin to stall development project was initiated between Anglo American Coal and Jennmar Australia(SPIN2STALLò). This paper summarises the journey of this project,the results,and the successful implementation of spin to stall achieved at Grasstree Mine.

A three-dimensional feature extraction-based method for coal cleat characterization using X-ray μCT and its application to a Bowen Basin coal specimen

Cleats are the dominant micro-fracture network controlling the macro-mechanical behavior of coal.Improved understanding of the spatial characteristics of cleat networks is therefore important to the coal mining industry.Discrete fracture networks(DFNs)are increasingly used in engineering analyses to spatially model fractures at various scales.The reliability of coal DFNs largely depends on the confidence in the input cleat statistics.Estimates of these parameters can be made from image-based three-dimensional(3D)characterization of coal cleats using X-ray micro-computed tomography(m CT).One key step in this process,after cleat extraction,is the separation of individual cleats,without which the cleats are a connected network and statistics for different cleat sets cannot be measured.In this paper,a feature extraction-based image processing method is introduced to identify and separate distinct cleat groups from 3D X-ray m CT images.Kernels(filters)representing explicit cleat features of coal are built and cleat separation is successfully achieved by convolutional operations on 3D coal images.The new method is applied to a coal specimen with 80 mm in diameter and 100 mm in length acquired from an Anglo American Steelmaking Coal mine in the Bowen Basin,Queensland,Australia.It is demonstrated that the new method produces reliable cleat separation capable of defining individual cleats and preserving 3D topology after separation.Bedding-parallel fractures are also identified and separated,which has his-torically been challenging to delineate and rarely reported.A variety of cleat/fracture statistics is measured which not only can quantitatively characterize the cleat/fracture system but also can be used for DFN modeling.Finally,variability and heterogeneity with respect to the core axis are investigated.Significant heterogeneity is observed and suggests that the representative elementary volume(REV)of the cleat groups for engineering purposes may be a complex problem requiring careful consideration.

鄂西黄壤和紫色土上小麦施用杂卤石效果研究

采用全生育期温室盆栽试验方法,以氯化钾处理为对照,研究了鄂西黄壤和紫色土上小麦施用杂卤石的效果。结果表明,在2种土壤上小麦施用杂卤石均显著增产,黄壤和紫色土上小麦子粒产量分别比对照高28.7%和46.6%,主要是由于杂卤石处理显著增加了小麦的有效穗数,黄壤和紫色土上小麦有效穗数分别比对照高31.2%和37.5%。在黄壤上,杂卤石处理的小麦,其钙和镁吸收量与对照基本持平,硫吸收量比对照增加44.6%;在紫色土上,施用杂卤石显著提高了小麦对钙、镁和硫的吸收量,提高幅度分别为7.7%、25.0%和81.8%,杂卤石在紫色土小麦上的施用效果比黄壤好,与紫色土有效钙、有效镁和有效硫的含量均较低有关。

Cooling pathways for deep Australian longwall coal mines of the future

Cooling of coal mines in the Bowen Basin, characterized by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be required to focus their cooling resources more intensively to manage a challenging thermal environment where virgin coal temperatures over 50 °C at a depth of 500 m are expected. Currently, mine cooling systems are employed to maintain the wet bulb temperatures(WBT) to below 27 °C at which point the risks of heat stroke or other heat related issues are manageable. The capacities of these systems are in the range of 6–10 MW refrigeration power. The relationship between high working temperature environment and injury frequency rates is well established. Therefore, provision of appropriate cooling strategies and understanding their optimum performance and suitability are important to Australian coal mines of the future. This paper evaluates the underground temperature profiles of deep, gassy coal mines with propensity for spontaneous combustion and proposes the long term cooling pathways to effectively manage the thermal hazards. Thermodynamic modeling is performed on a longwall face and includes air leakage effects from goaf streams at various locations along the longwall face. The strategy summarizes the application of underground bulk air cooling, chilled water sprays on the shearer and the resulting temperature profiles. Considering the new mining projects planned for the Bowen Basin region, a review of implementable cooling strategies such as mid-gate mobile bulk air coolers(BACs), spot coolers, underground bulk air cooling and the use of chilled water to enhance the positional efficiency of cooling plants,are discussed in this paper. Finally, the comparison of ‘rental' versus ‘ownership' of cooling plants is analysed as part of long-term cooling strategies.

中国商用车领域的铂族金属需求依然强劲(英文/中文)

2020年以来中国商用车市场发生了很多变化,近期卡车销量从疫情萧条中大幅反弹,物流、基建以及排放标准升级共同推动了2020年商用车市场需求,对铂族金属的需求更加有利,对铂金需求的预期增长似乎比对钯金需求更有保障。

Evaluation of gravimetric sampler bias, effect on measured concentration, and proposal for the use of harmonised performance based dust sampler for exposure assessment

The last three years has brought about alarming news of re-identification of coal worker’s pneumoconiosis(CWP)or‘black lung’in Australia after reporting nearly being absent for over five decades.While,the CWP statistics in South Africa(SA)are unverifiable,but certainly CWP has not been eliminated.These events have re-kindled the need for better understanding of the dust monitoring,performance of sampling devices,and compliance determination.Over the last half century,gravimetric sampling has been the fundamental means for dust exposure monitoring using recognised respirable size-selective standards.In both South Africa and Australia,the gravimetric sampling technique in coal mines has been followed since 1988 and 1983 respectively using samplers of original Higgins-Dewell(HD)type design.This paper provides the evaluation results of currently used South African and Australian gravimetric samplers compared against the original UK SIMPEDS‘true reference’sampler.The results consistently suggested that the South African and Australian cyclones do not conform to the required size selective curve or even the‘true’reference sampler.The results show that the currently used SA and Australian samplers showed a D50 sampling bias as high as 59%and 47%respectively against the size-selective curve.Similarly,under the controlled laboratory coal dust test conditions measuring the same coal mine dust level in a chamber,the South African,Australian and UK standard SIMPEDS sampler were 7.87,9.79 and 6.71 mg/m3 respectively,which aligned with the sampling bias.The differences can in part be attributed to the‘un-auditable’inherent design and manufacturing quality,or unverifiable data on sizeselective sampling curve.This finding has significant implications towards exposure data collected over the last 25 years and their subsequent use in the arrival of the dose-response curves.Therefore,it is strongly recommended that the harmonised use of‘true reference’SIMPEDS cyclone that meets the ISO(1995)criteria uniformly across the industry would benefit the exposure assessment and compliance determination.

Risk management in open cut coal mines

There are a number of geotechnical systems used at open cut operations of Anglo American's Metallurgical Coal business unit in Australia. These systems are mainly mine site specific, based on geological information and used as hazard plans. They are qualitative and reliant upon the experienced judgement of site based engineers and the general workforce. They are not suitable for calculating the associated risks of geological structures and mining responses. A uniform risk rating system that can be used to provide an unbiased, standard and quantifiable assessment of the risk from highwall and lowwall failures is therefore developed using the experience gained with such systems in Anglo American's South African operations. This system is a semi-quantitative risk rating system and takes into account the relative differences in the importance of hazards as experienced at each mine site as a result of different combinations of geotechnical factors and mining conditions. It is based on critical geotechnical and other parameters that have been identified by site mining engineers, geologists and geotechnical engineers. The primary advantage of this risk rating system is that all open cut mines in the Anglo American's Metallurgical Coal operations use a near identical system, which enables the user to compare the risk after each blast and with other mines. The system can be adjusted to meet local mine specific requirements. The implementation of this system, a computer program that automatically calculates the risks and recommends predetermined controls, has been made as practical and as easy to use as possible. This program can be used by personnel from other mining disciplines not directly related to geotechnical engineering.

未来氢能经济所需的铂资源是否充足(英文/中文)

对于未来氢能和燃料电池行业对铂金需求量的分析,市场人士的各种预测不尽相同。但是,我们相信即使在该行业出现了一个高增长的情况下,铂金的供应量也足以满足未来十年乃至更长时间的需求。

How relevant are engineering samples in the management of personal dust exposure?

A directive, legislated by the South African Department of Minerals and Energy(DME) in 1997, was introduced to reduce the dust exposures of continuous miner(CM) operators to below 5 mg/m3, when measured at the operator's cab position. The focus of this paper is to review the effectiveness of observing this rule for almost two decades and discuss industry perceptions arising from the application of this rule. The results have demonstrated that the engineering sample cannot predict the personal shift dust exposure of a CM operator. Therefore, it is recommended that the engineering sampling, as currently practiced,should be reviewed with the objective to discontinue and replace it by the approved PDM3700 realtime dust monitor.

汽车领域用铂替代钯--不是“要不要”,而是“什么时候”的问题

2017年,钯有史以来第二次比铂还贵。由于铂相对于钯的新价格优势,我们研究了把它用在汽油车催化转化器上的可能性。汽油车和油电混合动力汽车的销量预计将持续增长,这应该会促使该领域的钯供应愈加紧张。我们认为钯供应的增长,包括原矿开采和回收在内,不太可能满足下一个十年里不断增长的钯需求。基本的经济理论表明这将导致汽车领域的需求受抑,汽车制造商将不得不减少每辆车的钯用量。在催化转化器中使用铂替代钯看起来对汽车公司是最切合实际的途径,在符合减排规定的同时减少钯用量。虽然在汽油催化转化器中使用铂还有一些壁垒,不过我们认为这些是可以克服的并且相信汽车催化剂行业的钯总需求中至少25%可以轻而易举地被铂替代。虽然用铂替代汽油车催化剂中的钯的过程势必会困难重重,不过我们认为2020年初有望开始商用。

Proactive interburden fracturing using UIS drilling with validation monitoring

A series of gas inrush events occurred during development at Grosvenor Mine resulting in exposure to elevated levels of methane at the production face.A total of 22 gas inrush events occurred,with between 15 and 130 m3 of methane released during each event.The presence of an undrained seam in the immediate floor,geotechnical characteristics of the floor,and the stress environment all contributed to these dynamic floor events,while the geological characteristics of the seam below,such as the seam thickness and ash content of 75%,prevented effective predrainage.However,events only occurred in headings mined parallel to the principal horizontal stress direction.In cut-throughs(C/T)perpendicular to the principal stress direction no events occurred,and higher methane levels were observed at the production face.The solution to preventing the gas inrush events involved creating a conduit in the interburden between the mined seam and the seam in the immediate floor to allow the gas to be drained during the development of the headings,as occurred in the cut-throughs(cut-through and cross-cut are regional terms that are analogous).A series of underground inseam(UIS)holes were drilled using the directional drill rig with the aim of fracturing this interburden ahead of the face and promote floor failure to allow the gas to release consistently.The floor fracturing was conducted using water pressure generated from a longwall salvage pump,with the current UIS drilling equipment retrofitted with a series of subs,packers and a fracturing tool.The packers and the fracturing tool were shifted to desired locations along the drilled UIS borehole to achieve the required fracture.The fractures were monitored using a proving hole and with a HYDAC data logger attached to the salvage pack,with the results analysed on the surface to ensure connectivity to the working seam.

Improved TARP development based upon mine specific data

The trigger action response plans （TARPs） are inherent to managing the multiple hazards such as： high gas content with multiple coal seams, high spontaneous combustion （sponcom） propensity, heat and ventilation, TARPs aim to provide assurance and guidance when the situation deviates from the original plan or there is a change conditions that could he hazardous, Over the years, learnings from various incidents has continuously required the coal operations to re-visit the TARP trigger values that were based on historic data or based on guidance values from the industry, In most cases, the background to the basis of TARP statistical data, viz,, average, maximum, hourly, daily for the monitoring or sampling location is also unknown, Introduction of real-time monitoring devices to monitor the gases and airflows has provided greater understanding of the hazard scenarios and their controls, This paper analyses the carbon monoxide data from operating longwall mines and compares these with the historic trigger values to understand the changes and determine improvement opportunities while setting trigger levels in the TARPs, As an example of setting trigger values, those used in during the sealing of a panel are explored in terms of setting values based upon the sampling location and the level of risk, It is envisaged that the learning＇s shared herein would further enhance the understanding and management of multiple hazards in Australian coal mines,

铱资源是否足以支撑未来氢能经济的发展

铱在氢能经济中的主要角色是和铂金一起作为质子交换膜电解水制氢反应的催化剂。目前铱在质子交换膜电解水制氢领域的消费量为每年几百千克。预计到2030年,用于质子交换膜电解水制氢的铱年需求量将达到1 t。如果质子交换膜电解水制氢产能大幅增长,铱的用量也会相应增加,而且铱在其他工业领域未来可能也会带来需求增长。估计铱的地质储量约3000 t,每年铱的矿产量约为7 t,铱的可获得性不会成为未来大规模制取绿氢的限制因素。

“未可言说之美”:评《美与崇高:文艺认知美学》——兼与帕特里克·霍根教授商榷

美国康涅狄格大学文学认知研究专家霍根教授再推力作《美与崇高:文艺认知美学》(1);该书尤其旨在为文学中诸多纷繁的个体审美反应探求一种结构性主张,同时借助与认知科学的对话,使得文学美学研究中那向来"未可言说"的部分获得空前的认知审美观照。本文拟聚焦于"信息加工"与"情感机制"、"审美共性"与"个性品味"以及"变奏""经典化"与"审美争议"等三大关键节点,在对它们加以厘清的同时,凸出围绕文学认知研究路径中出现的相关问题加以商榷。

Unwrapping reworked crust at the Columbia supercontinent margin within central southern Amazon Craton using multi-source geophysics and geochronology data synergy

The geometry and evolution of pre-existing basement in accretionary belts bordering supercontinents are often unclear.Integrative interpretation of long-wavelength potential field satellite data can image deep crust structure,improving our understanding of lithospheric processes that formed these margins bottom-up.Here,we present a multidisciplinary interpretation of the lithospheric architecture of the central southern Amazon Craton,a fragment of an accretionary belt at the southwestern Columbia supercontinent margin.Satellite-borne gravity and magnetic data,airborne magnetic data,passive seismic(V_(p)/V_(s) ratio,crustal thickness)and seismic tomography data reveals that basement terranes from the interior of the craton extend into the accretionary margin of Columbia.We demonstrate a vertically heterogeneous structure with an underlying strongly reworked pre-Columbia tectonic wedge that sustained prolonged modification during the supercontinent assembly as corroborated by Nd isotope and geochronology data.Nd isotope data suggest that the protracted orogenic wedge was influenced by subduction angle shifts over time,including addition of substantial juvenile material during slab retreat events.This interplay promoted Craton growth at the supercontinent margin while keeping a subtle record of the pre-existing framework.Our findings point to the possible misrepresentation of basement extension and geometry of supercontinent margins elsewhere.

Solvent Extraction Developments in Southern Africa

The largest solvent-extraction plant in the world at the time, the Nchanga Copper Operation, was in Zambia. The first commercial process using solvent extraction for the refining of the platinum-group metals was in South Africa. More recently, the Southern African region has seen the implementation of solvent extraction for other base metals, precious metals, and specialty metals. These include the world firsts of primary production of zinc at Skorpion Zinc in Namibia and the large-scale refining of gold by Harmony Gold in South Africa. Several other flowsheets that use solvent-extraction technology are currently under commissioning, development, or feasibility study for implementation in this part of the world, including those for the recovery of copper, cobalt, nickel, tantalum, and niobium.