Acid activation of clays is a process in which sulphuric acid is usually used in order to obtain a material with enhanced surface properties. Several researchers have studied acid activation of aluminosilicates by using mineral acids. An alternative method to sufficiently producing acid activated minerals with eliminated environmental cost, however, could be achieved by using oxalic acid. Oxalate is a polyfunctional organic acid that forms strong complexes with aluminum and ferrous ions and enhances the dissolution rate of the minerals. It also has high acidity and preserves the clay structure during activation. Moreover, effluents resulting from oxalic acid activation are considered more environmentally friendly than those resulting from activation by inorganic acids. The main advantage of using oxalic acid is the formation, during activation, of soluble complexes which can be decomposed both microbiologically and under the action of daylight.
The target of this work was to compare the surface and structural properties of the materials produced by oxalic acid activation of different smectite samples with the conventional inorganic acid activation.
The physicochemical characteristics of raw materials and products were evaluated by various methods: X-Ray Fluorescence (XRF), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and BET (Brunauer-Emmett-Teller) and BJH methods for specific surface area measurement and definition of pore size distribution of the samples.
Results showed that acid activation led to new materials with higher specific surface areas and diverse porosity, compared to the raw materials. The organic and inorganic acid activation products presented structural differences which effluent their appropriateness to adsorb undesirable organic molecules.
As the highly respectable Mining Journal (issue 20. May 2019) recently stated: “Mining may have pedigree, with its roots in the Bronze Age, but with direction and momentum established over some 5,000 years it also has the turning circle of the QEII and, as such, has long been regarded as an innovation and technology laggard among industries.” This reputation is currently changing fast with major international mining companies and the World Bank Group jointly promoting “The growing role of Minerals and Metals for a Low Carbon Future” [1].
Traditional comminution systems for ores such as ball and SAG mills are trusted for their robustness but also known for their inefficiency, particularly in energy consumption and general rock breakage [2]. With more than 50 % of energy being consumed in a typical mining operation for crushing and milling and – even worse – only 1 % of the energy consumed by a conventional ball mill used for breakage and the rest wasted as heat, there is huge potential for radical improvement.
The VeRo Liberator® was invented some 6 years ago and achieves high-velocity, high-frequency impact comminution through a vertical four-fold axle-in-axle system with hammer tools, rotating clockwise and anticlockwise [3]. The impacts produce highly turbulent particle flow and trigger fracture nucleation and propagation at and along phase boundaries. With energy consumption being reduced by over 70 % and particle liberation far superior to conventional systems, this new technology offers huge operational and economic advantages. The VeRo Liberator® operates dry and thus produces waste that does not require dewatering and allows for safer direct dry stacking.
The VeRo Liberator® achieves its drastically energy-efficient particle size reduction and particle liberation by high-velocity impacts that achieve an efficient momentum transfer into the ore particles. This leads to the disintegration or quasi “explosion” of the ore particles, predominantly without actual contact with the impact tools. Consequently, the VeRo Liberator® uses less energy, shows surprisingly little wear, and operates at very low noise levels. Market entry of the VeRo Liberator® technique was achieved in 2017 and several units are now performing in industrial-scale operations or are on their way to installation for Anglo American. It is now up to the wider mining industry to test and embrace the new technology and develop it to its full potential.
The underground coal mine operating environment is harsh, and mine accidents occur frequently. The automation of underground safety and production management is an important technical way for coal mine enterprises to achieve safe operation and improve production efficiency. [1] The mine roadway not only undertakes the transportation channel for daily production, but also the main escape route for the staff in emergency situations. Therefore, the environmental monitoring of the main roadway of the mine is the basis for ensuring production and safety. [2] At present, the monitoring of roadway deformation mainly adopts manual measurement [3]. This method cannot achieve real-time continuous monitoring and early warning purposes. The automatic transmission and long-distance communication functions especially cannot be realized. Therefore, according to the characteristics of roadway deformation and domestic application, an automatic monitoring and early warning system for surrounding rock deformation of underground mine roadway was developed. The monitoring system collects monitoring data through a series of sensors and passes the microprocessor and RS485 bus. When a dangerous situation is found, the computer will send an AT command to the GPRS (General Packet Radio Service) module according to the set procedure. After receiving the command, the GPRS module will send an alarm message to the set mobile phone. The monitoring system accomplishes the continuous real-time monitoring of the deformation speed of the surrounding rock of the roadway. The data transmission distance is long, the operation is simple, and the single monitoring station is small in size and light in weight, which is particularly suitable for deformation monitoring of various mine roadway projects.
Keywords:Applying power ultrasound during solidification has proven to be an effective way to improve the microstructure and enhance the mechanical properties of metallic alloys. However, most previous investigations focus on the dendritically solidified Al or Mg based single phase alloys, the effect of power ultrasound on the multiphase alloys, including eutectic, pertiectic and monotectic alloys are still remains unclear. In present work, the solidification mechanism of these three kinds of metallic alloys is summarized on the basis of the authors’ work.
For binary Sn-Pb eutectic alloy, differing from the regular lamellar eutectic formed during static solidification, there are two typical kinds of spherical eutectic cells formed within the ultrasonic field. Theortectical analysis shows that the local high undercooling induced by cavitation takes responsibility to the formation of anomalous eutectic, while the radial symmetry of both the concentration and temperature fields induced by acoustic streaming ensures that the solid-liquid interface is symmetric in three dimensions.
As for binary Cu-Sn peritectic alloy, the ultrasonic field brings about a striking size refinement effect to the primary intermetallic compound by more than one order of magnitude. Meanwhile, it facilitates or even completes the usual peritectic transformation which occurs only to a very limited extent during static solidification. These lead to the remarkable improvement of mechanical properties for such Cu–Sn alloy, whose compressive strength and microhardness are both remarkably increased.
Power ultrasound is also introduced to the liquid phase separation and dynamic solidification of ternary Cu-Sn-Bi monotectic alloy. It is found that as compared with the layered structure formed under static condition, the macrosegregation resulted from liquid phase separation is remarkably reduced with the increase of ultrasonic amplitude. This is mainly ascribed to the ultrasonically induced cavitation and acoustic streaming, which promotes the nucleation, the fragmentation, and the dispersion of secondary droplets. The finally solidified immiscible alloy exhibits obvious improvements in electrochemical corrosion resistance, microhardness and wear-resistance.
My career as a metallurgist with a U.S. copper mining company ASARCO LLC (Asarco) has been bookended with stints of consulting with Arthur D. Little, Inc (A.D. Little) before my tenure at Asarco and with tfgMM Strategic Consulting, a firm I founded after retiring from Asarco in 2015. This paper discusses how my consulting experience prepared me for my sustainability journey. Dr. Arthur Dehon Little, a Massachusetts Institute of Technology chemist who co-founded the company believed that science and technology can be used to solve societal problems and is illustrated by two examples—making a silk purse from a sow’s ear and flying a lead balloon. My sustainability journey began with the presentation in Bhubaneswar, India of a paper co-authored with Asarco’s Vice President of Governmental Affairs in 1998. That paper examined the trends facing the mining industry, one of which was the application of sustainable development principles to mining.
The last 15 years of my tenure at Asarco provided an in-depth opportunity to research and be involved in projects that promoted sustainable development. Based on the classic Brundtland Commission definition of sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” this paper describes how metal mining can be compatible with sustainable development and how sustainability considerations have been applied in the primary copper industry, using selected examples of sustainable mining past and current practices from Asarco operations.
The metals mining, smelting and refining industry has been and will continue to be an essential contributor to the economic and social development for generations to come. The demand for minerals and metals will grow to satisfy the needs of a growing world population which is anticipated to grow from 7.7 billion to 9.6 billion by 2050. In order to meet the challenge of declining ore grades, industry will have to focus on increasing productivity through automation, big data analytics and technological and business innovation. It will face challenges related to regulation, geopolitical risks and demands for increasing transparency from increased scrutiny from shareholders, investment community and the public. There will be pressures to transition to a low-carbon economy. Companies in order to succeed in this environment will have to skillfully navigate these challenges and seize on the opportunities. The papers to be presented in this Symposium address the technical, environmental and socio-political aspects of sustainable development as applied to mining.
Finally, this paper discusses how these considerations might be used in the future by discussing the need for developing a sustainable development strategy and how this strategy can be aligned with the United Nations Sustainable Development Goals.
Backfill technology is regarded as an important technological carrier to realize safe, green and efficient deep mining [1]. According to the coupled problems of high-stress, high-temperature and multitudinous-goaf, etc., in deep mines, as well as high-cost of backfill mining, an academic ideal of Functional Backfill (FB) was put forward. The proposed FB can not only realize the function of traditional backfill, but can also achieve the expanded functions, i.e., cold-loading, heat-saving, energy-storage, seepage-proofing, etc.
Firstly, the concepts of Functional Backfill Materials (FBM) and Functional Backfill Technology (FBT) were scientifically defined, and the conceptual model of the FBM was established. Secondly, from the functional point of backfill materials, the evolution process of backfill technology can be divided into three stages, e.g., volumetric backfill, structural backfill and functional backfill. Finally, on the basis of backfill material functions, the functional backfill were classified as Cold Load /Storage-Functional Backfill (CLS-FB) [2-3], Heat Storage & Release-Functional Backfill (HSR-FB) and Cavity-building -Functional Backfill (CB-FB).
Correspondingly, the concepts, functions and basal principles of the mentioned three functional backfill were presented in detail. The application and exploration of functional backfill materials & technologies will further improve the backfill technologies in mines, which have an important and far-reaching impact on the deep mine geothermal co-exploitation, underground goaf reuse and strategic energy reserves, etc.
In 2009, NASA launched the LCROSS mission to the South Pole of the moon to perform a spectral analysis of the contents of the crater material remotely. The results of the mission were positive with strong indications of H2O and other materials from the analysed plume of material. This began worldwide speculation on returning to the moon with countries setting up programs to consider lunar prospecting and exploration to be followed by creating initial mining plans.
Finding H2O engaged the world in plans for emerging opportunities for new space based industries. Cheap abundant water allows consideration of potentially cheap fuel which is very available. Inexpensive off-earth propellant could be used for future satellite refueling, science missions within the solar system and beyond, and enables commercial missions for mining, hotels and industry.
The military in the USA created the first lunar mining plan in 1959. Since that time, many have been created with varying levels of credibility. In 2006, the Canadian Space Agency requested Dr. Baiden to devise a plan for lunar mining. This question resulted from the mining robotics research at his labs in Sudbury Ontario Canada. The plan was created over a two year timeframe and was presented to the AAIA in 2010. It was subsequently refined through work with Shackleton Energy and is now being further refined by a new start-up called MoonRise.
Lunar prospecting and exploration will require teleoperated control of exploration robots from earth. There is much work in the literature, showing successful teleoperation with time delays of 2-3 seconds. This type of lunar surface operation has already been performed by NASA and Russia. The data on the size and quality of the H2O will soon be validated by lunar surface missions in order to consider mining feasibility. Mining plans that have been performed from an aerospace perspective have little real mining work being considered by miners with industry experience.
From a miner's perspective there are four major issues that need to be dealt with if lunar mining is to become a reality. These are: gravity, temperature, radiation and the lack of atmosphere. In all terrestrial applications, miners use gravity to their advantage. In thinking about lunar gravity, one sixth gravity is a major consideration. On one side, gravity requires less work, but in actual fact, the same work for mining needs to be done as on Earth. In terms of temperature, H2O is located in the cold traps of these polar craters. If we mine in warmer areas, the H2O immediately vaporizes, so we must mine in the cold traps at -250°C or 25 kelvin. Current mining experience limits are digging tools in the oil sand at -70°C. Finding and creating robots and mining tools to work in these temperature environments is another major consideration. As a mining facility, operations can be teleoperated or made autonomous, however, maintenance is a different story. Replacement parts will need changes, so a minimum amount of personnel will be necessary on site. This ground truth means a local habitat will need to be created for operations to occur. And finally, solar radiation is the main constraint for personnel on site as it has a large potential to be the literal fatal flaw. The numbers show extreme danger for personnel without proper protection. Adaptation of terrestrial tunneling technology, however, could provide a simple solution to this dilemma by enabling underground access to get to a sufficient level of protection.
This paper presents current thinking from a miner's perspective. This mining plan has been presented and augmented by input from CSA, NASA, Shackleton Energy Co., and now MoonRise Inc.. It identifies the main "show stoppers" or risks for mining H2O from the moon. The next steps include a recent statement by a major US launch company (United Launch Alliance) of willingness to buy lunar propellant in space. Note this substantially reduces customer or business risk. NASA has also expressed interest in purchasing locally manufactured lunar propellant.
Nearly every decision-making process in mineral research or the mineral industry depends on analytical data. It is not sufficient, however, to merely data. The data must be traceable and comparable. Precise results are not good enough to warrant reliable data. The lack of accuracy can cause seriously biased results and erroneous decisions. Certified reference materials (CRMs) play an important role in assuring analytical results of high quality. A CRM is a material that is sufficiently stable and homogeneous with respect to one or more specified properties which establish the CRM to be fit for its intended use in a measurement process. This is characterized by a metrologically valid procedure, accompanied by a certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability [1]. Its uses may include the calibration of a measurement system, assessment of a measurement procedure, assigning values to other materials, and quality control [2]. CRMs are also used in interlaboratory comparisons for method validation and for assessing laboratory proficiency. The demonstration of the scientific and technical competence of reference material producers (RMPs) is a basic requirement for ensuring the quality of CRMs. It is not only necessary for RMPs to provide information about their materials in the form of CRM documents, but also to demonstrate their competence in producing CRMs of appropriate quality [3].
The Center for Mineral Technology (CETEM), a R&D Institute under the Brazilian Ministry of Science, Technology, Innovations and Communications, has been accredited as an ore and mineral certified reference material producer in accordance with ISO 17034 since June 2011. The production concerns all necessary activities leading to a reference material supplied to customers, including production planning, production control, material handling and storage, material processing, assessment of homogeneity and stability, characterization, assignment of property values and their uncertainties, issue of certificates and post-distribution service. The Certified Reference Material Program (PMRC) was established to coordinate all management and technical aspects of the production of certified reference materials at CETEM. It has a fully equipped laboratory for handling large amounts of material, preventing contamination among samples, as well as from outside sources, and a qualified technical team that is committed to ensuring the quality of the reference materials produced. Currently, the majority of CETEM’s certified reference materials are bauxite ores originating from various regions in Brazil. There is a continuing effort for the development of other natural matrix reference materials, driven by the needs of analytical laboratories associated with mining, metallurgy and the environment. CETEM also provides custom-made CRMs from client-supplied materials in order to meet a specific or special application need.
This paper describes the production of CETEM’s certified reference materials.
Cemented paste backfill is an increasingly popular technique to improve ground stability in underground mines[1]. This technique is used in several mining methods that require strength evaluation for the vertically exposed cemented backfill following the excavation of an adjacent stope on one side. The critical strength is generally evaluated with an analytical solution proposed by Mitchell et al. [2]. Despite its wide acceptance in academia and application in the mining industry, the Mitchell solution has received only a few updates in the literature, including some new developments given by the authors and colleagues[3].
The original Mitchell solution and its variants were mainly validated against the physical model test results obtained by Mitchell et al. [2]. Even though the Mitchell model debatably assumed a zero backfill friction angle, the required strengths predicted by the Mitchell solution corresponded quite well to those obtained by physical model tests[4].
This study reanalysed the Mitchell solution and its physical model. The testing conditions and procedures for measuring the shear strength parameters are investigated. The stability of the cemented backfill upon removal of a confining wall is analysed with FLAC3D. The comparisons between the numerical modellings, experimental results and analytical solutions are presented, and the applicable range of the classical Mitchell solution is discussed.
A new analytical solution is proposed to evaluate the minimum required strength of the cemented backfill confined by two sidewalls exposed on one side and subject to pressure from uncemented backfill on the opposite side. The proposed analytical solution is validated by numerical simulations with FLAC3D.
The proposed analytical solution is used to determine the theoretical strength requirement of cemented backfill in primary stopes of an iron mine that employs stage stoping with subsequent backfill mining. The floating Factor of Safety (FS) characterising the current backfilling quality control level of this mine was statistically evaluated with a large amount of uniaxial compressive strength (UCS) data after testing vast drilled samples from field stopes. The engineered strength requirement of the cemented backfill in primary stopes had been finalised by combining the analytical results and floating FS of the mine.
This paper presents an experimental study on the strength and suction evolution of cemented paste backfill (CPB) and CPB that contains blast furnace Slag (Slag-CPB) with different content of sulphate at early ages. CPB and Slag-CPB with 0, 5,000, 15,000 and 25,000 ppm sulphate content were prepared and cured at room temperature (20°C) for 1, 3, 7 and 28 days. Mechanical, hydraulic conductivity test and microstructural analyses were performed on the studied samples, suction and electrical conductivity of the samples were monitored. The results show that sulphate has a significant negatively effect on the early age strength and suction evolution of CPB and can lead to a positive or negative effect on Slag-CPB i.e., cause an increase or decrease in strength and acceleration or reduction in the amount and rate of self-desiccation. Inhibition of cement hydration and pozzolanic reaction, ettringite induced coarseness of pore structure and sulphate absorption by C-S-H are found as main reasons that affect CPB strength and suction evolution. This study has demonstrated that the effect of sulphate on the early strength and self-desiccation of CPB is an important factor for consideration in the designing of cost-effective, safe and durable CPB structures as well as using slag for reducing the mining cycle time in sulphide mines.
Keywords:As extraction rates of finite mineral resources, and the relative environmental impacts of these activities grow globally (Kesler, 2007; Parameswaran, 2016), initiatives to improve the sustainability of mining have been undertaken (Parameswaran, 2017). A framework for the assessment of sustainability of mining is needed. A review of existing thoughts at the intersection of sustainability and mining has been performed to identify existing frameworks. A common sustainable mining framework is focused on reducing environmental impacts of mining through measuring, monitoring, and working to improve various environmental performance metrics. A more comprehensive framework is emerging, however, that takes into account the complete life cycle of the mineral and includes circularity metrics and a systems view of mineral use in society. This transition from the emphasis on the environmental footprint of mining operations to responsible management of non-fuel mineral resources throughout their entire life cycle, including use phase and end of life, has benefits including reducing the quantity of mined material and preserving reserves for future generations (Gorman and Dzombak, 2018).
In this work, through the collection of primary stocks and flows data for the complete copper life cycle from 1970 to 2015, life cycle and circularity analyses were applied to assess sustainability of copper mining, use and recovery in the United States. This is followed by dynamic modeling and assessment of the data. The circularity, and therefore sustainability, of copper is found to be limited by end of life collection. This is mostly from building and construction and electric utility sectors, as well as exports of scrap which limit availability of recyclable copper material in the U.S. and requires raw material imports and continued extraction of virgin materials.
Copper prices are determined by world supply and demand. The increasing demand for a higher quality refined copper product from ores containing as little as 0.5% copper; varying levels of valuable constituents such as gold, silver, platinum group metals, nickel, selenium and tellurium; and potentially destructive impurities such as arsenic, antimony, lead and bismuth provide the impetus for researching, developing and implementing innovative process technologies in several areas within the copper electrorefining operation.
Recent technological innovations have allowed companies to reduce inefficiencies (e.g., energy consumption, waste generation) and unit costs while meeting increasingly stringent environmental, safety, and health regulations. One promising approach is the adoption of processes incorporating green chemistry, which is defined as “the design of chemical products and processes to reduce or eliminate the generation of hazardous substances.” It has become evident that incorporation of green chemistry principles into innovative process development has helped support investment decisions for these new processes.
This paper presents several examples of green chemistry technologies which have been implemented at copper electrorefineries, including (1) use of SuperLig® Molecular Recognition Technology (MRT), a highly selective technology capable of achieving loading to elution ratios of more than 40 bed volumes (BV) and flowrates above 0.2 BV/minute, in controlling antimony and bismuth concentration levels in copper electrolyte and for the separation of platinum group and other metals in electrorefining; (2) the recovery of sulfuric acid and arsenic in electrolyte purification using acid purification technology via an acid purification unit (APU®) in comparison to the conventional liberator cell (electrowinning) process; (3) recovery of tellurium from copper anode slimes initially through a cementation process followed by alkaline leaching, and (4) recovery of metals such as lead and nickel in electrolyte purification using a selective two-step alkaline precipitation.
Sustainable development is a development that achieves the present needs while making sure that the needs of future generations are taken into account as well.
Today, clean and smart technologies play an important role in sustainable development; including economic efficiency, environmental and social aspects.
Mining industries elevate the lives of millions of people around the world, mainly in rural areas. Therefore, sustainable development in the mining industry focusing on innovative and clean technologies is much needed. Mining agriculture, tourism, clean process technologies, and wastewater treatment are the examples which secure future jobs and protect the environment creating smart communities.
Existing and developed digital and clean technologies will assist the industry to be sustainable. Process Research Ortech (PRO) is helping and focusing on developing innovative clean technologies for mining industries for many years. The paper will include innovative technologies that are developed at PRO for Gold, Nickel, Titanium and water treatment.