A. Mohamed, Abdou Azizi Oupoungam, Taha Boyraz
et al.
In the artisanal gold mining industry, due to the use of the inefficient amalgamation process, high-grade gold and an alarming quantity of mercury-containing tailings are released to the environment. Although these tailings pose serious environmental risks, they also represent a potentially lucrative source of gold. This study investigates tailings from artisanal gold mining (ASGM) in Cameroon, employing a comprehensive characterization approach that includes physical, chemical, and mineralogical analyses, as well as hydrometallurgical methods such as traditional cyanidation and innovative glycine leaching, complemented by ion exchange to recover metals from the leaching solution. Mineralogical analysis indicated that the sample predominantly consists of quartz and some low-grade silicate and iron minerals. The main constituents were SiO2, Al2O3, and Fe2O3. The gold, silver and mercury grades of the sample were 14, 4 and 8 ppm, respectively. The median particle size of the sample (d50) was 360µm. MLA results showed that some of the gold and silver electrums are locked inside quartz, pyrite and muscovite particles. The results of leaching experiments revealed that by applying cyanide leaching, 87% of gold recovery was reached, while the recovery rate of glycine leaching remained around 45%. On the other hand, neither lixiviants did achieve a satisfying mercury recovery, which remained around 30%. The process of grinding the sample resulted in a modest enhancement in the recovery rates of gold and silver; however, it adversely affected the leaching efficiency of mercury during cyanide leaching. The AmberSep M91419 ion exchange resin demonstrated significant efficacy in extracting metals from both cyanide and glycine solutions.
Beryllium (Be) is a relatively rare element and occurs naturally in the Earth's crust, in coal, and in various minerals. Beryllium is used as an alloy with other metals in aerospace, electronics and mechanical industries. The major emission sources to the atmosphere are the combustion of coal and fossil fuels, and the incineration of municipal solid waste. In soils and natural waters, the majority of Be is sorbed to soil particles and sediments. The majority of contamination occurs through atmospheric deposition of Be on aboveground plant parts. Beryllium and its compounds are toxic to humans and are grouped as carcinogens. The general public is exposed to Be through inhalation of air and the consumption of Be-contaminated food and drinking water. Immobilization of Be in soil and groundwater using organic and inorganic amendments reduces the bioavailability and mobility of Be, thereby limiting the transfer into the food chain. Mobilization of Be in soil using chelating agents facilitates their removal through soil washing and plant uptake. This review provides an overview of the current understanding of the sources, geochemistry, health hazards, remediation practices, and current regulatory mandates of Be contamination in complex environmental settings, including soil and aquatic ecosystems.
R.A. Abdulvaliev, Tatiana Surkova, Zhazira A. Baltabekova
et al.
The decrease in the quality of mineral raw materials processed by industry, as well as the increase in requirements for environmental protection, necessitate the development of new directions in the technology of their processing. Biogeotechnology refers to one of the modern areas of scientific and technological progress in the field of processing mineral raw materials. Biologically active additives are increasingly used along with the use of microorganisms in the extraction processes for non-ferrous and precious metals, in particular amino acids which are an integral part of the culture liquid of microorganisms. The processes of sulfuric acid leaching of copper from low-grade ore in the presence of amino acids of different structures and their effect on copper electrolysis were studied. Low-grade ore from one of the Kazakhstan deposits was used as the starting raw material. The copper content in the ore is 0.39%. The diffusion nature of the restrictions was established during the study of the kinetics of the process of sulfuric acid leaching of copper, and the rate constants and value of the effective activation energy were calculated, which amounted to 1.817 kJ/mol. The effect of amino acids with different structures on the leaching process was studied. The positive effect was increased in the glycine - leucine - cysteine - histidine - asparagine series. Depending on the structure of the amino acid, the degree of copper extraction into the solution increases in the range of 1-15%. The effect of aminoacetic acid as a biologically active additive on the process of electrolysis of copper from poor solutions was studied. It was established that the process is inhibited by the reduction of monovalent copper to the metallic state in the presence of glycine.
Economic and military power have rested on the possession of metallic minerals for many centuries; far longer than has been the case with hydrocarbons. Since minerals are unevenly distributed around the world, there have been many instances in history where countries have sought to bolster or extend their power by the acquisition of minerals from others through trade or through territorial expansion (empire-building). This article explores the interplay of mining, metals and power, through case studies of Ancient Rome, Spain during its colonisation of South and Central America, Britain’s maritime empire, and the Soviet Union’s belated and rapid industrialisation during the twentieth century. These case studies serve to make the point that current concerns in the USA, Europe, Japan and China about the vulnerability of their economies and military capabilities to the disruption of mineral supplies from overseas are nothing new, although the range of minerals now used, the complexity of modern supply chains and prevailing geopolitical norms suggest that there may not be too much in the historical record to assist these countries and regions address their concerns.
Critical raw materials are essential for various industries due to their importance, significance, and various applications. They are classified into various types, such as rare earth elements and strategic minerals, and have key characteristics such as scarcity, high economic importance, and geopolitical implications. Factors influencing the availability of critical raw materials include geological factors, environmental challenges, regulations, trade, and geopolitical factors. Global demand and supply of critical raw materials are also analyzed, with a focus on recycling and sustainable practices. Potential risks and challenges associated with critical raw materials include environmental and social impacts, dependence on these raw materials, and dependence on foreign countries. Understanding these factors is crucial for ensuring the continued success of critical metals in various industries. The research paper discusses the importance of critical metals in the circular economy, their definition, and the research's objectives. It also discusses the circular economy concept and its relevance to resource management, identifying critical metals and their specific roles, and discussing challenges and opportunities related to their use. The article focuses on the potential for critical raw material management within the circular economy. The study's goal is to investigate and analyse the various tactics and methodologies that can be used to successfully utilise, recycle, and reintroduce key metals into the economy. The circular economy is viewed as a method of improving sustainable resource management by closing the material flow and encouraging renewability and recycling. The circular economy is currently understudied in the context of critical metals - a set of raw materials that are vital for modern technology but are limited in supply and cause significant environmental damage.
Deus Albert Msumange, Joshua Albert Msumange, Kathy Bru
et al.
This paper aims to provide an overview of tungsten (W) tailings properties, detrimental impacts of these tailings, approaches to mitigate these impacts, and a presentation of methods to reprocess them to capture their economic value. Since W is widely used in a variety of industries, it has been extensively mined since the 19th century, and the mining continues to generate significant volumes of tailings. Recent data show that global W production stands at 84 kt per year, and more than 100 Mt of W tailings exist containing over 100 kt of WO3. The tailings contain variable amounts of valuable products and deleterious environmental substances. Some of the contained metals are in great demand for the energy transition. However, these tailings usually contain FeS2/Pyrrhotite and FeAsS minerals, which, when exposed to air and water, can produce acid mine drainage. As such, W tailings may pose environmental and human health risks. Globally, the reprocessing of W tailings presents a potential resource that can be regarded as a paradigm of sustainability and circular economy. Flotation, enhanced gravity separation, and wet high-intensity magnetic separation have been reported to be the common approaches to reprocessing W tailings. However, W processing presents particular difficulties owing to complex material properties, such as fine particle size, surface weathering, similarity in surface properties exhibited by gangue materials (fluorite, apatite, calcite), low concentrations of the elements of interest, and poor mineral liberation.
Sri Handayani, Reginawati Hindersah, Sunbaek Bang
et al.
Purpose. This research aims to characterize the Langkat quartz mineral, especially its impurities, and to study the effectiveness of fungal-based leaching methods to purify the mineral in order to improve the quartz quality for high-tech industrial applications. Methods. Quartz was firstly analyzed to identify the mineral and chemical impurities. Quartz purification and beneficiation was performed by direct bioleaching using live indigenous Aspergillus niger, indirect bioleaching using metabolic lixiviant of the fungus, and chemical leaching using analytical grade oxalic acid. Findings. The mineral composition of the Langkat quartz deposit is dominated by quartz mineral (93%) with minor amounts of orthoclase feldspar (KAlSi3O8, 5%) and calcite (CaCO3, 2%). The chemical composition comprises 98.1% SiO2 with metal impurities of 0.8% Fe2O3, 0.29% Al2O3, 0.03% NiO, 0.028% Cr2O3 and 0.063% CuO, indicating that quartz is still not enough for advanced material production industry. The bioleaching process removes up to 98% of iron (Fe2O3) from the original quartz sample, and completely removes other metals within eight days of the process by direct bioleaching and eight hours by indirect bioleaching. The content of Fe2O3 and other metals in the treated quartz meets the specifications of high purity quartz (≤ 0.05%) for advanced material production industry. Meanwhile, chemical leaching using 0.2 M oxalic acid removes 96.9% of iron and 92.8% of aluminium. Originality. Comparison of the bioleaching potential of present indigenous Aspergillus niger with some of the previous studies shows that this strain has a higher ability to remove metal impurities from quartz in a much shorter processing time (8 hours instead of weeks or months) than most of the previously published microorganisms. Practical implications. The experimental result of this research provides significant potential for using a fungus-based purification approach to obtain high-purity quartz to be used in a high-value-added modern commercial product.
Electronic waste (e-waste) is generated in enormous amounts worldwide, and this has become a global environmental issue because of the way it is handled, especially in developing countries. Africa undoubtedly is the fastest growing economy than any other continent, and this has resulted in increase in the importation of electronic and electrical goods and in the implementation of information and communication technologies. However, owing to inadequate infrastructure for e-waste management and nonenforcement of laws, multitudes of hazardous substances are released due to the crude way e-waste is recycled and could pose risks for humans and the environment. On the other hand, a lot of opportunities abound if it is handled well. These include precious metal recovery for industry, employment opportunities and economic benefits to e-waste collectors, helping to clean the environment, refurbishment for sale of cheap electronic and electrical equipment, benefits of recovered metals over mineral mining, among others. E-waste management is an issue in Africa because of the increasing global production of electronic and electrical equipment, lack of clear action plans by African governments on the handling of e-waste, and the absence of infrastructure for appropriate e-waste management.
The article assesses the situation and analyzes the current trends in the development of domestic foreign trade through the case of Dnipropetrovsk region. The analysis is conducted through the lens of identifying challenges and opportunities for the region that are opened up by foreign trade. The impact of the region's foreign trade on its international economic relations in the context of Ukraine's European integration and the deployment of globalization processes is significant. Dnipropetrovsk region is one of the leading exporters and, according to the results of 2018, ranks second place among the regions of Ukraine by the export of goods. Therefore, choosing the region for the study is determined by the importance of the development of international trade in its territories to strengthen the position of Ukraine's international competitiveness. The article identifies and analyzes the indicators of foreign trade of the Dnepropetrovsk region with the world countries, as well as the economic result and effect of it’s influence. The focus is put on assessing and analyzing the dynamics of changes in the structure of export and import of goods. In particular, the tendency of decrease in export of services of Dnepropetrovsk region to the EU countries during 2014-2017 is analyzed as a negative trend. Positive trend visualizes through increasing of this indicator in 2018. Overall, the increase of the number of regional enterprises engaged in the foreign trade of goods was shown. Emphasis is placed on the commodity structure of export. It is composed of ferrous metals (46.3%) and ores, slag and ash (23.2%). The basis of the commodity structure of import is mineral fuels; oil and its distillation products (30.3%), machinery, equipment and mechanisms; electrical equipment (14.4%), chemical products and related industries (11.3%), and precious metals (11%). The dynamics of the change in the export structure indicates a certain slowdown in the process of transition to a ‘new type economy’, which should be based not on direct consumption of resources, but on innovation, knowledge and technology, their application in products and services production. The article is a summary of the situation in the field of foreign trade of the region, which is carried out in the framework of the task of drafting the Strategy of development of Dnipropetrovsk region for the period until 2027.
Technological advancements dictate the productivity growth in all industries, including extractive ones. In the peculiar case of metallic mineral industries, this growth is also impacted by the natural variation in the metal content and chemical composition of the ore input, in the course of cumulative extraction and depletion of resources. Through a disaggregated treatment of productivity data achieved by using the input-output data on subprocesses of copper production and correlating them with input characteristics (ore grade), this study identifies and evaluates the impacts of the periodic changes in the natural input, as well as those of the technological progress, while reasonably controlling the influence of the other unrelated factors. This provides an objective assessment of the manner and extent of mitigation of the impact of the depletion-driven changes in the natural inputs of the said industry, through technological advancements. It reveals that the continuous and incremental developments in technology, successfully offset the detrimental effects of depletion on the copper sector productivity, often aided by the geological characteristics that changed to the miners’ advantage. However, the impact of depletion stands to outweigh the gains from innovative technologies, as soon as the ores breach a minimum threshold level of purity or chemistry. This study thus establishes the usefulness of productivity studies in estimating the impacts of depletion that may not proceed in strictly sequential and uni-directional manner. More importantly, it shows that the impacts are neither uniform nor linear and are not always detrimental to productivity growth. Though the study is primarily based on copper industry, the findings hold relevance for other metal industries too.