Operational ore/waste classification at a surface gold mine

Abstract

The daily determination of ore blocks and waste blocks in a surface gold mine can be formulated as a binary integer programming problem. While the geometric mining constraints complicate the problem beyond the capabilities of standard algorithms, the special structure of the problem allows the development of a fast alternative. Using the theory of generalized Lagrange multipliers, the problem can be decomposed into a series of one dimensional problems amenable to a dynamic programming solution.     

MULSOPS: Multivariate Optimized Pit Shells Simulator for tactical mine planning

Abstract

Production planning, scheduling and allocation of resources in large-scale surface mining operations present a great challenge to mine planning engineers. Ore and waste extraction plans must be executed to achieve tactical objectives using appropriate tools. Many production planning and scheduling and resource allocation methods are based on trial and error, crisis management or subjective judgements with no detailed economic basis or mathematical rigour. In addition, these methods do not consider the random processes governing critical development and production variables. In this study, the authors develop a multivariate pit shell simulator, MULSOPS, which addresses these problems. Rigorous geometric formulations of the ellipsoidal approximations of the pit shells geometry, their expansions and sequential interactions are modeled to mimic material displacement dynamics in an open pit operation. Stochastic and numerical modeling techniques are used to provide solutions to the time-dependent geometric models in random multivariate states Under different production and economic paradigms, the geometric models are simulated to yield the source and characteristics of appropriate cuts. Combined production from successive exposed cuts provides periodic targets for tactical planning. Variance simulation is also used to provide analysts with sensitive stochastic variables for input data definition and tight production target tolerance. A numerical example is used to illustrate the use of MULSOPS for tactical planning in a typical open pit operation.     

Pollution of Water and Stream Sediments Associated with the Vale De Abrutiga Uranium Mine,Central Portugal

Abstract.   The Vale de Abrutiga uranium deposit, located in Central Portugal near the Aguieira dam reservoir, was surface mined. Low-grade ore and waste rock were deposited on permeable ground, close to the mine, and were not revegetated. A lake has formed in the open pit. Surface waters draining the mine site are acidic, have high conductivity, and high concentrations of U, SO42-, Zn, Fe, Mn, Ra, Cu, Th, and Pb. The groundwater and the water from the reservoir cannot be used for human consumption or irrigation. The sampled waters show higher contaminant concentrations in winter than in summer. Stream sediments have high geoaccumulation indices for U, Fe, Ag, Zn, Cr, Co, and Pb. In general, sediments bordering the dam reservoir have higher metal contents in winter than in summer.     

Effectiveness of mineral waste management

Abstract

Mineral waste is a side effect of mineral industry activity. In the case of metal industry, flotation waste generated during ore treatment and slag produced in metallurgical processes are large in quantity. Implementation of effective methods for utilisation of waste is one of priorities, leading to measurable economic and environmental effects. Taking these facts into consideration, four effectiveness models were proposed and analysed in terms of waste management in current processes as well as waste utilisation in new products. Calculation algorithms for all models have been developed.     

Variable zone modeling – A different approach to ore deposit modeling

Abstract

Geology and separation of ore and waste are two fundamental factors in modeling epigenetic deposits. Epigenetic deposits are those deposits where there is a time lag between the deposition of the ore and the host rock. Geologic features such as lithology, facies, and faults are important contributing factors in ore deposition and should be taken into consideration during data categorization and modeling. Separation of ore and waste should-be handled at the block level. Even though the conventional block modeling technique is claimed to take geology into consideration, this is not accomplished to the extent necessary to produce a representative model and to take advantage of, all the available information. A new modeling technique developed by MK-Environ-mental, called “variable zone modeling” (VZM), takes these geologic features into consideration during data categorization and continues using related information throughout the modeling process.     

Geostatistics applied to short-term mine planning

Abstract

Geostatistics is being used today for long-term mine planning (e.g., ore reserve estimation and mine model development) and for production scheduling (e.g., ore-waste selection) at many of metal mines in the U. S. Geostatistics is not as yet used for short-term mine planning, although geostatistics provides ideal tools to satisfy several goals of short-term mine planning.

This paper reviews the probable reasons for the lack of geostatistical applications in short-term mine planning and demonstrates the practicality of routine implementation of the University of Arizona's short-term mine planning system, if there exists either an economic or a political incentive to do so.     

Completion criteria - Case studies considering bond relinquishment and mine decommissioning: Western Australia

ABSTRACT

The Western Australia Government Agencies controlling environmental bond assessment and land relinquishment after mine decommissioning advocate proactive environmental management. Meeting environmental objectives ensures return of bond monies and facilitates release of the Company from environmental obligations. Completion criteria that confirm establishment of a self-perpetuating and resilient vegetation cover over mine waste are being developed. Post-mining land use generally reverts to maintaining the natural ecosystem or rangeland. Within this climatic zone very distinct vegetation communities are closely linked to soil substrate classification. Matching surface waste characteristics from a mine waste dump with those of surrounding analogue communities is the first step in determining an achievable vegetation cover. Examples of the methodology as applied to one Western Australian mine site, a semi-arid location (annual rainfall 320?mm) (Westonia - 31°18'S, 118°42'E) is presented. There has, at Westonia, been establishment of Eucalypt Woodland on mildly saline waste surfaces. The combination of direct seeding at the appropriate sowing time and good topsoil management, has led to successful revegetation of a suite of species with all life forms represented.     

Optimizing short-term production schedules in surface mining: Integrating mine modeling software with AMPL/CPLEX

Abstract

Short-term production scheduling is the operational basis for mine production over time spans of days, weeks and months. Short-term schedules concentrate on making long-term mine plans operationally feasible and ensuring a steady flow of product for both meeting gross production targets and blending ore. Mathematical programming techniques have been applied to optimize short- and long-term production schedules, but widespread application of these techniques has been limited by the use of routines that are opaque to the end user or difficult to implement. Several examples are provided to illustrate the advantages of using the math modeling language AMPL in conjunction with Techbase, a popular mine modeling package. The strengths of MIP methods as applied to production scheduling are discussed, as are techniques for coping with the limitations of these algorithms.     

Oil sands mine planning and waste management using mixed integer goal programming

Strategic mine planning and waste management are an important aspect of surface mining operations. Recent environmental and regulatory requirements make waste management an integral part of mine planning in the oil sands industry. The research problem here is determining the order of extraction of ore, dyke material and waste to be removed from a predefined ultimate pit limit over the mine life that maximises the net present value of the operation. We have developed, implemented, and tested a proposed mixed integer goal programming theoretical framework for oil sands open pit production scheduling with multiple material types. The formulation uses binary integer variables to control mining precedence and continuous variables to control mining of ore and dyke material. There are also goal deviational variables and penalty costs and priorities that must be set up by the planner. The optimisation model was implemented in TOMLAB/CPLEX environment. The developed model proved to be able to generate a uniform schedule for ore and dyke material. This is in line with recent regulatory requirements by Alberta Energy Resources and Conservation Board (Directive 074) which requires oil sands mining companies to develop life of mine plans which ties in to their in-pit tailings disposal strategy. It also provides a practical mining sequence that is consistent with mining oil sands deposit. Similarly, tradeoffs between achieving a goal and maximising NPV can be made.     

Examples of open pit mining instability

Abstract

Geotechnical technology for surface mining has become increasingly sophisticated as lower grade ore deposits are being developed. With larger and deeper open pits, more detailed and accurate investigation has become necessary during the past decade.

Many variables influence successful open pit operations. These include ore grade, metal price, development costs, construction costs, mine design, stability and operating costs. With the great increase in the size of open pits to depths over 600 ～ 800 meters, the determination of pit slope angle and control of wall stability has a major influence on project economics.

This paper briefly discusses preliminary considerations for pit slopes from a geotechnical standpoint to optimize economics and safety, describes recent developments in stability engineering and to illustrate a wide range of stability problems, typical examples are briefly reviewed.     

Mathematical expressions for simulating a dragline mining system

ABSTRACT

Mathematical expressions for simulating a dragline mining system are presented. Six particular cases grouped into two categories -with and without rehandling of removal material- are simultaneously considered while designing a two-dimensional sequence of cuts. A system of non-linear equations resulting from a material balance established between the overburden material to be removed and the space available for spoiling into, produces the solution to the unknowns that define the geometry of a cut. Constraints associated with both the operative dimensions of a dragline and the fulfilment of a minimum ore production target are jointly considered as part of a model for simulating dragline land movement. Results from a real case illustrate the selection of a dragline having the minimum operating cost among several others tendered by their manufacturers.     

回填废石层下放矿损贫预测及颗粒流数值分析

露天转地下开采,回填废石层在放矿过程中对矿石的损失和贫化有一定的影响。回填废石层下放矿损贫的主要影响因素有回填层厚度、废石的粒径和非均匀度3个方面,对不同试验者的实验数据重新处理,总结出了回填废石层下放矿贫化率和损失率的数学模型,并结合司家营铁矿Ⅲ采场的露天转地下工程进行了回填废石粒径与非均匀度的设计。通过颗粒流数值正交试验方法,分别从绝对因素和相对因素回归建立了贫化率λ、回填层厚度h、回填层粒径d、回填层粒径非均匀度K4个因素和损失率之间的关系,为类似条件下的回填层合理设计提供参考。     

铁矿废石综合利用研究进展

随着我国铁矿资源的不断开采,不可避免地产生大量废石,伴随着绿色矿山理念的深入,这些铁矿废石的处理及利用一直是各地矿山企业关注的热点和难点.当前,我国对铁矿废石的处理手段主要包括采空区回填、工程运用、回收铁矿石以及制备砂石骨料等多种方式.本文在介绍当前我国铁矿废石资源基本情况的基础上,综述了近些年来国内外铁矿废石资源的综...     

矿山废石对环境的污染及其综合利用研究现状

在矿产资源开采过程中会产生大量不含矿的围岩和夹石,称为废石.废石是一种固体废弃物,一般以堆存的方式存放.随着我国对矿山环保要求的不断提高,废石的大量堆存及其造成的环境污染已成为现在亟需解决的问题.本文介绍了矿山废石堆存对周边水体、土壤和大气造成的危害,并指明目前这类废石的综合利用方式主要包括有价金属提取、工程化利用以及...     

铀废石、尾矿最终处置技术探讨

本文对铀废石、尾矿的辐射特性及对环境危害作了分析，探讨了铀废石、尾矿的最终处置技术，结合我国铀矿山环境治理经验，提出了最终处置的建议。     

基于Dmine的数字化矿山生产配矿研究

对于夹层较多,矿石品位相差较大的石灰石矿体,尽可能多地利用低品位矿石或废石,其关键是制定周密的配矿计划。为了达到最优的配矿目的,首先利用Dmine软件建立数字化模型;然后基于详细的地质勘查数据进行生产配矿。结果表明,经过配矿不仅可以降低矿山生产剥采比,提高企业的经济效益,同时,又减少废石的排放,降低环境污染的程度。     

Predicting Geochemical Behaviour of Waste Rock with Low Acid Generating Potential Using Laboratory Kinetic Tests

Techniques developed for acid mine drainage (AMD) prediction might not be suitable for contaminated neutral drainage (CND) generating sites. The Tio mine waste is known to generate Ni contaminated neutral drainage in some of the piles, but humidity cell tests fail to generate the Ni concentrations observed in the field. Weathering cell tests (small-scale humidity cell tests) were performed on fresh and weathered (produced 25 years ago) waste rock samples from the Tio mine containing various levels of hemo-ilmenite ore, and results were compared to humidity cell results on similar samples. The main constituents of the waste rock are the hemo-ilmenite ore and the plagioclase gangue; these minerals were purified from the waste rocks and the purified fractions were also submitted to weathering cell tests. The fresh waste rock samples were also submitted to sorption cells (modified weathering cells), which showed that the waste rocks have an important Ni sorption potential and that the sorbed phases are stable under weathering cell conditions. Even though the Ni concentrations obtained from the laboratory tests remain significantly lower than those obtained in field conditions (from field test pads and from waste rock piles), the results from the present study give important insight into the geochemical processes implicated in CND generation.     

Kinetic Testing and Sorption Studies by Modified Weathering Cells to Characterize the Potential to Generate Contaminated Neutral Drainage

Techniques developed for acid mine drainage (AMD) prediction might not be suitable for contaminated neutral drainage (CND) generating sites. The Tio mine waste is known to generate Ni contaminated neutral drainage in some of the piles, but humidity cell tests fail to generate the Ni concentrations observed in the field. Weathering cell tests (small-scale humidity cell tests) were performed on fresh and weathered (produced 25 years ago) waste rock samples from the Tio mine containing various levels of hemo-ilmenite ore, and results were compared to humidity cell results on similar samples. The main constituents of the waste rock are the hemo-ilmenite ore and the plagioclase gangue; these minerals were purified from the waste rocks and the purified fractions were also submitted to weathering cell tests. The fresh waste rock samples were also submitted to sorption cells (modified weathering cells), which showed that the waste rocks have an important Ni sorption potential and that the sorbed phases are stable under weathering cell conditions. Even though the Ni concentrations obtained from the laboratory tests remain significantly lower than those obtained in field conditions (from field test pads and from waste rock piles), the results from the present study give important insight into the geochemical processes implicated in CND generation.     

铁蛋山矿床露天转地下开采的实践

通过保国铁矿铁蛋山矿区露天转地下开采实践,顺利地解决了铁蛋山矿区露天转地下开采挂帮矿石回采,强化开采露天底部矿石,形成废石覆盖层,保证选矿生产,地下开采采矿方法的选择等问题,取得了良好的效果,实现了对矿区资源和机械设备利用的最大化,并保证了过渡时期矿石的生产能力,创造了巨大的经济效益,为我国中等规模的露天转地下开采的矿山提供了成功的样板。     

Combined extraction of metals and production of Mg(OH)2 for CO2 sequestration from nickel mine ore and overburden

Carbon storage by mineralisation (CSM) is an option for CO₂ emissions mitigation that has been under intensive study at Åbo Akademi (ÅA), Finland. Magnesium from silicate rocks is extracted with recoverable ammonium salts at 250–500 °C. The extracted elements are separated by selective precipitation and Mg is subsequently carbonated in a pressurised fluidised bed. This work studies the applicability of the process for co-extraction of Ni, Cu, Fe and Mg from nickel ore and nickel mine waste rock (overburden). The rock samples were collected from the Hitura Nickel mine, Finland. The results show that it is possible to co-extract the listed elements and integrate CSM (by the ÅA process) with steelmaking and Ni production industries.