Toward Sustainable Mining: Exploring Alternative Mineral Resources and Innovative Extraction Techniques

Optimisation of production planning for an innovative hybrid underground mining method

The broad objective of this research was to improve current surface mining practices and reduce negative environmental impact of overburden removal in West Virginia (WV). The specific objectives were to (i) compare conventional surface mining method (drilling, blasting, digging, and loading) to a surface miner (SM) method, and (ii) apply the analytical hierarchy process (AHP) to help select the optimal mining method based on production, cost and environmental criteria. The design and the procedures used in this research involve five interrelated modules: (i) rock properties of overburden in WV, (ii) drilling and blasting, (iii) digging and loading, (iv) SM method, and (v) comparative analysis and selection of the optimal mining method by AHP. Results of this research indicate that application of SM method would yield higher cost of overburden removal than conventional mining methods in rocks with a high unconfined compressive strength and abrasivity. A significant advantage of SM method, where applicable, is the elimination of the negative environmental impacts associated with blasting.

The greenhouse gas footprint of in-situ leaching of uranium, gold and copper in Australia

Summary. One possible drawback to the use of in-situ leaching to recover uranium is the potential release of previously insoluble chemical species into the formation water. Before a pilot test of in-situ uranium leaching at Crownpoint, NM, was begun, extensive laboratory studies were undertaken to develop chemical methods for treating one possible contaminant, molybdenum (Mo). New Mexico regulations restrict the amount of Mo permissible in formation waters after leaching to less than 1 ppm. permissible in formation waters after leaching to less than 1 ppm. Two techniques to restore Mo after leaching were studied with core and pack tests. These studies suggest that if Mo restoration problems occur in the field, the use of precipitating agents such as Ca 2 + or reducing agents such as Fe 2 + may be helpful in ameliorating such problems. Introduction Typically, uranium has been produced by conventional underground mining and surface milling methods, but insitu leaching has recently emerged as an attractive alternative for uranium recovery. Before an in-situ leach operation to produce uranium in the Westwater Canyon member of the Morrison formation near Crownpoint, NM, was begun, comprehensive laboratory studies of ore mineralogy and leachate formulations were undertaken. The resultant pilot test was the deepest (2,000 ft [610 m]) successful in-situ uranium leach test carried out in the U.S. and the first operation of its type conducted in New Mexico. While in-situ leaching has significant advantages over conventional uranium recovery methods, one possible drawback is the release of previously insoluble chemical species into the formation water. Of course, conventional mining also has the potential to mobilize hazardous trace metals in the environment, as indicated by the elevated concentrations of Mo in waters downstream from the large Mo deposit at Climax, CO. Before the start of the Crownpoint pilot test, laboratory testing was undertaken to develop chemical methods for treating one possible contaminant, Mo. Ore analyses from the Westwater sands at the Crownpoint pilot site revealed Mo occurrences in the intended leach zone. In-situ production of uranium entails oxidizing uranium from the insoluble +4 oxidation state to the soluble, readily complexed +6 state, i.e., However, this process also transforms insoluble Mo 4+ minerals such as molybdenite or jordesite, both MoS2, into the soluble +6 form, molybdate, MoO4 2-, i.e., Current New Mexico environmental regulations restrict the amount of Mo permissible in formation waters after leaching to less than 1 ppm. Restoration of formation water to acceptable levels for each of the dissolved solids is the final phase of leaching operations. Three recent reports deal with restoration operations in in-situ uranium leaching in a most comprehensive manner. The main difficulty is that the original chemicalreducing environment underground has been changed to an oxidizing one during the leaching process. Undesirable species can continue to be slowly released from underground rock surfaces long after the primary leaching has ceased. Obviously, the contaminants need to be rendered insoluble. To reduce Mo levels in groundwater after leaching operations, there are at least two methods of restoration:the MoO4 2- may be precipitated by addition of a cation orthe oxidizing environment can be changed to a reducing one, converting the Mo back to the less soluble +4 oxidation state, perhaps to Mo3 O8. The latter technique has been characterized by Henry et al. as recreating the original mineralization process. Both techniques were studied in the experiments described in this report. Calcium ion (Ca2+ was used to precipitate MoO4 2 -. Ferrous ion (Fe2+ a reducing precipitate MoO4 2 -. Ferrous ion (Fe2+ a reducing agent, was studied to see whether it could render Mo insoluble. JPT P. 1301

Closure issues vary depending on the mining method, creating different biophysical challenges on the surface and underground. In turn, mining methods depend mainly on the geology of the ore deposit, which itself is defined by regional characteristics, such as morphology and local tectonics, etc. The closure is an important factor in developing and planning new mines but is often subordinate to other factors. The mining method is often selected based on pre-feasibility studies and there is limited ability to change the operational characteristics once implemented. If the ability to close the mine, re-use the landscape and contribute to the community and post-mining economy is to become driving factors in the selection of the mining methods and subsequent mine operations, then they should also be carefully considered in early decision-making. A few new mining methods have been proposed for zero-entry and invisible mining that leave waste in place and reduce ore movement. Since these methods require the use of alternative technologies, such as robotics for automation, leaching, and efficient cutting, they will introduce a different set of biophysical issues that will affect the closure and post-mining land use. The potential benefits may be outweighed by their risks, or they may introduce a new set of opportunities for closure at a lower cost and with minimal biophysical risks. This study has, therefore, aimed to compare the biophysical closure impacts of conventional and novel mining methods and to identify if the new mining methods, especially in-place mining, support a business case for closure that enables and motivates the industry to adopt these new mining methods. We identify, compare, and contrast biophysical impacts on post-mining land use for in-place mining methods relative to more traditional mining methods using desktop studies, workshops, and interviews with member company representatives. The study also identifies opportunities to use new mining methods that enable alternative closure options. The study develops and uses a comparative matrix that compares the biophysical impacts of novel mining approaches with the more traditional mining methods (e.g., open pit mining, underground stope mining, and cave mining). The study highlights the current problems, identifies transformational opportunities, and determines future activities that could enable mining methods with improved closure outcomes. The biophysical impacts of different methods should be compared quantitatively, although the current reference site approach has flaws. The use of the rock engineering system enabled quantitative analysis of the survey data, though highlighted that many experts are unaware of the biophysical impacts at closure. The findings also show that the new mining methods are expected to modify and reduce the closure issues relative to the conventional mining methods, which often require large open pits, voids underground, and large tailings footprints. Further investigation is needed to further develop the novel mining methods and to evaluate the applicability of the methods for local small operations as the transition point to full-scale adoption.

Marble is an ornamental stone, extremely popular for use as architectural and sculptural purposes. Nonrenewable marble resources in Khyber Pakhtunkhwa (KP), Pakistan are mostly mined by conventional mining methods(producing irregular shaped blocks) instead of using mechanized mining producing regular shaped blocks.Conventional mining methods are more economical but are less environment friendly due to more quantity of wasteproduced. While, mechanized marble mining has a better recovery, reduces mining cost (processing and transportation)and is less environmentally hazardous. In this study a situation and sustainability analysis of marble mining operationsat Buner, the most productive marble mining cluster in KP, Pakistan, is carried out. Buner has about 1.4 billion tons ofmarble resources and contributes around 51 percent of total country’s marble production. Analytical Hierarchy Process(AHP) is used on the basis of key sustainability factors (economic, technical, social, environmental and safety) forselection of most sustainable mining methods. The analysis revealed that conventional mining is least sustainable andproduces maximum waste, cracks, irregular shaped blocks, high working faces, back break, rock falls and accidents. Itwas concluded and recommended that these conventional mining methods should be replaced with the more sustainablemining methods i.e. semi-mechanized (controlled blasting / expansion material) at sunny grey and get black marbledeposits and mechanized mining (rope cutting) at Bampokha No.1 and Chagharzai white marble deposits.

Marble is an ornamental stone, extremely popular for use as architectural and sculptural purposes. Nonrenewable marble resources in Khyber Pakhtunkhwa (KP), Pakistan are mostly mined by conventional mining methods(producing irregular shaped blocks) instead of using mechanized mining producing regular shaped blocks.Conventional mining methods are more economical but are less environment friendly due to more quantity of wasteproduced. While, mechanized marble mining has a better recovery, reduces mining cost (processing and transportation)and is less environmentally hazardous. In this study a situation and sustainability analysis of marble mining operationsat Buner, the most productive marble mining cluster in KP, Pakistan, is carried out. Buner has about 1.4 billion tons ofmarble resources and contributes around 51 percent of total country’s marble production. Analytical Hierarchy Process(AHP) is used on the basis of key sustainability factors (economic, technical, social, environmental and safety) forselection of most sustainable mining methods. The analysis revealed that conventional mining is least sustainable andproduces maximum waste, cracks, irregular shaped blocks, high working faces, back break, rock falls and accidents. Itwas concluded and recommended that these conventional mining methods should be replaced with the more sustainablemining methods i.e. semi-mechanized (controlled blasting / expansion material) at sunny grey and get black marbledeposits and mechanized mining (rope cutting) at Bampokha No.1 and Chagharzai white marble deposits.

A mobile application has been developed for selecting the most convenient underground mining method for a mine by employing well-known multi-criteria decision-making methods such as TOPSIS, VIKOR, ELECTRE, FMADM and PROMETHEE. The developed mobile application can carry out the selection process by prioritising valid alternative set of underground mining methods for taking into account some decision factors which are not considered in the conventional underground mining method selection approaches. In this way, the engineers are able to use this application for the selection of underground mining method on their mobile devices in anywhere.

About one quarter of the coal produced in Australia is by underground mining methods. The most commonly used underground coal mining methods in Australia are longwall, and room and pillar. This paper provides a detailed review of the two methods, including their advantages and disadvantages, the major geotechnical and operational issues, and the factors that need to be considered regarding their choice, including the varying geological and geotechnical conditions suited to a particular method. Factors and issues such as capital cost, productivity, recovery, versatility and mine safety associated with the two methods are discussed and compared. The major advantages of the longwall mining method include its suitability for mining at greater depth, higher recovery, and higher production rate compared to room and pillar. The main disadvantages of the room and pillar method are the higher risks of roof and pillar collapse, higher capital costs incurred as well as lower recovery rate.

In the last few decades, many underground mining methods were proposed for extractions of ores. The decision-making for selecting the most suitable mining method for a typical ore depost depnds on various intrinsic and extrinsic factors (intrinsic – dip, shape, thickness, depth, grade distribution, RMR (rock mass rating) and RSS (rock substance strength) of ore, hanging wall, footwall, and extrinsic – recovery, dilution, safety, productivity, flexibility, capital). The present study aims to develop a hierarchical Fuzzy-AHP (FAHP) model for choosing the most suitable underground mining method for an ore deposit. The structure of the proposed hierarchical FAHP model consists of five levels. The level-1 of the hierarchy defines two variables (intrinsic factors and extrinsic factors). These are further classified into quantitative or qualitative nature of variable (listed in level-2). The criteria, sub-criteria, and mining method variables are listed respectively in Level 3, Level 4, and Level 5. For each level of the hierarchy, a fuzzy pair-wise comparison matrices are developed using the corresponding levels’ listed variables. These matrices at each level are subsequently used to determine the local and global weights of each variable. The global weights are used for prioritizing the different mining methods. The proposed hierarchical FAHP model was validated by considering the field data of two different ore deposits in India. The results showed that the most appropriate mining method predicted from the decision-making model and the adopted mining method for extracting the ore deposit are same in two case studied mines.

The goal of a Mineral Resource statement is to estimate the in-situ tonnage and grade that might reasonably be expected to be extracted using the contemplated mining methods. Despite the transition by the mining industry to the use of computer-aided methods for preparing Mineral Resource estimates, the fundamental realities of complying with the CIM Definition Standards requirement of “Reasonable Prospects for Eventual Economic Extraction” (RPEEE) have not changed. Computer-aided block modeling can result in an irregular, patchwork of blocks above and below cutoff grade, termed the checkerboard effect. In such cases, for underground mining methods, strict application of a block cutoff grade does not consider the impact of any internal dilution blocks that may be present, while also potentially including blocks above cutoff grade that may not have sufficient spatial continuity. Considering the block dimensions relative to the selectivity of the potential underground mining method, this can result in material errors in Mineral Resource statements. The impact of the checkerboard effect varies from deposit to deposit. While several techniques are currently employed by Mineral Resource practitioners to ensure compliance with the RPEEE requirement of a Mineral Resource, practitioners are encouraged to develop additional methods and techniques that provide reasonable results.

Coal is China’s main source of energy, and its production causes a certain degree of air, water, and land resource pollution. Therefore, it is necessary to compare environmental pollution caused by different mining methods. When mining underground coal resources, different mining methods have different levels of environmental impacts. To identify the mining method with the least environmental impact, different mining methods were evaluated by means of a life cycle assessment using Simapro 9.0.0 software. The Ecoinvent v3 database was used to provide background data, and the results were calculated using the Eco-indicator99 method. The findings show that for a 20 m coal column, respiratory inorganics were identified as the dominant impact category based on normalized results, followed by fossil fuels, carcinogens, and climate change. The contribution analysis indicated that electricity and coal mining are fundamental in contributing to these significant impact categories and should be of particular concern. According to the sensitivity analysis, reducing mining activities and increasing extraction efficiency and use are the primary responses to addressing environmental pollution, followed by reducing environmental pollution caused by electricity and steel production. In addition, a summary comparison of the single scores of different mining methods suggests that the environmental burden of pillarless mining is the lowest, and as the width of the coal pillar gradually increases, its single score shows a trend of increasing and then decreasing. Therefore, the single score of non-pillar mining is the lowest compared to that of other mining methods and can be the optimal mining method. This study can provide a scientific basis for the selection of green mining and underground coal resource mining methods.

Relevance. Insufficiently high labor productivity at coal mining enterprises actualizes a study to increase the efficiency of their activities based on the factor of productivity growth. Purpose – substantiation of a possible increase in labor productivity with a change in the ratio of open and underground mining methods. Methodology – analysis of changes in labor intensity with various options for the share of open and underground development methods, as well as assuming an increase in production. Results. Issues of effective production and economic activity of coal industry enterprises are considered taking into account the factor of increasing labor productivity of workers. For the efficient functioning of coal mining enterprises, certain correlations should be fulfilled between the rates of change in the volume of coal production, labor productivity and the cost of coal production. Changes in coal production can be achieved mainly by the ratio of underground and open-cast mining. An approach to determining the level of labor intensity of work in the coal industry with a change in the ratio of underground and open coal mining methods is proposed; with a corresponding increase in labor productivity, the unit cost of production in the planning period is determined. The factors of growth of labor productivity in the coal industry are given: an increase in the utilization rate of combines for sewage treatment and bucket excavators for opencast mines; progressive changes in the design and operational characteristics of the main coal mining equipment; the use of imported equipment only in economically feasible mining conditions; the possibility of growth of stimulating factors to ensure the corresponding labor productivity of coal mining workers; increase in the share of coal from mines and opencasts with low cost of coal mining. Conclusions. The approach developed by the authors to determine the level of reduction in the labor intensity of work in the coal industry can be used in conditions of changing the ratio of open and underground mining methods, and accordingly, the change in the cost of production of one ton of coal as a whole for the joint-stock company can be forecasted.

The paper provides an overview of the many challenges facing prospective underwater mining ventures and an overview of processes which have been proven to be successful in overcoming these challenges. The paper is based on 15 years of practical consulting and project experience working with a diverse set of clients and client needs. The information provided will be beneficial to business and project managers involved with exploration and for new mineral resources and underwater sampling and mining systems development. Underwater mining has been practiced for centuries, but in recent times we have seen both success and failure. As land based resources diminish and technology developments progress, underwater mining has become increasingly accepted as a viable alternative source of minerals to land based resources. Successful operations are built on sound system identification and development processes of the resource, the equipment and the management processes. It is becoming increasingly important to not only focus on the technical solutions but also the system acquisition processes and subsequent operations management of underwater mines to ensure sustainable success. In order to initiate a sound acquisition process it is necessary to develop a comprehensive set of system requirements which will satisfy the business need. Together with these requirements it is also crucial to gather sufficient geotechnical information to enable mining tool design. It is equally important to be aware of and manage the regulatory and environmental aspects during the development process. The process of licensing and approval can take years, and as such, it is necessary to initiate these processes very early in the mine development cycle. Mines within the exclusive economic zones are governed by the coastal nations legislation, and mines beyond that are governed by the International Seabed Authority. System acquisition requires a structured approach to ensure successful identification, selection and development. Due to the relatively recent and progressive move into underwater mining there are few ‘off the shelf’ solutions and as such it must be accepted that there will be some level of development in most if not all underwater mining projects. Challenges include clients unfamiliar with the underwater mining environment, lack of geotechnical information, ore-body variability, reliance on research and development, early investment requirements during the project cycle, and limited benchmarking opportunities. Specific project implementation and operations challenges are in many cases similar to the offshore industry. Challenges include space and weight constraints, implementation in foreign countries, and complex integration of marine, mining and beneficiation plant equipment on highly congested work sites. Mining is by nature a harsh working environment for both people and equipment. A thorough development process of both the resource and the mining systems, and sufficient investment in personnel and equipment can however mitigate the risks and set resource license holders up for many years of profitable operations.

Seawater reverse osmosis (SWRO) desalination generates a concentrated brine byproduct rich in dissolved salts and minerals. This study presents an extensive economic and technical analysis of recovering all major ions from SWRO brine, which includes Na, Cl, Mg, Ca, SO4, K, Br, B, Li, Rb, and Sr in comparison to conventional mining and chemical production of these commodities. Data from recent literature and case studies are compiled to quantify the composition of a typical SWRO brine and the potential yield of valuable products. A life-cycle cost framework is applied, incorporating capital expenditure (CAPEX), operational expenditure (OPEX), and total water cost (TWC) impacts. A representative simulation for a large 100,000 m3/day SWRO plant shows that integrated “brine mining” systems could recover on the order of 3.8 million tons of salts per year. At optimistic recovery efficiencies, the gross annual revenue from products (NaCl, Mg(OH)2/MgO, CaCO3, KCl, Br2, Li2CO3, etc.) can reach a few hundred million USD. This revenue is comparable to or exceeds the added costs of recovery processes under favorable conditions, potentially offsetting desalination costs by USD 0.5/m3 or more. We compare these projections with the economics of obtaining the same materials through conventional mining and chemical processes worldwide. Major findings indicate that recovery of abundant low-value salts (especially NaCl) can supply bulk revenue to cover processing costs, while extraction of scarce high-value elements (Li, Rb, Sr, etc.) can provide significant additional profit if efficient separation is achieved. The energy requirements and unit costs for brine recovery are analyzed against those of terrestrial or conventional mining; in many cases, brine-derived production is competitive due to avoided raw material extraction and potential use of waste or renewable energy. CAPEX for adding mineral recovery to a desalination plant is significant but can be justified by revenue and by strategic benefits such as reduced brine disposal. Our analysis, drawing on global data and case studies (e.g., projects in Europe and the Middle East), suggests that metals and salts recovery from SWRO brine is technically feasible and, at sufficient scale, economically viable in many regions. We provide detailed comparisons of cost, yield, and market value for each target element, along with empirical models and formulas for profitability. The results offer a roadmap for integrating brine mining into desalination operations and highlight key factors such as commodity prices, scale economies, energy integration, and policy incentives that influence the competitiveness of brine recovery against traditional mining.