The exchange of hard mineral resources during this time period was MOST important to the

VI Metallogenic Patterns in Time

Though mineral deposits can be described in terms of spatial plate tectonic relationships, it has been thought by some that mineral deposit types may also have changed with time. For instance, most of the earth's iron ores were formed at around the transition period from Archean to Proterozoic, which is also taken as the period during which the earth developed an oxygen-bearing atmosphere (the oxy-atmo inversion). Lambert and others suggested that there were three evolutionary stages in earth history, and hence in mineral deposits. The earliest was the Greenstone Belt Stage, followed by the Cratonization Stage, and finally the Stable Craton-Rifting Stage. Watson suggested that during the Archean, when the crust was supposedly hotter, most mineral deposits were derived relatively directly from the earth's mantle. With the change to the Proterozoic about 2.7 Ga, there was an increase in the variety of ore deposits, particularly with the first sedimentary deposits formed then, including uranium and iron formations. Later, mineralization became increasingly more variable, being derived directly from the mantle and by the numerous surficial processes, particularly the blossoming of organic activity, which recycled metals already dispersed in the continental crust.

Meyer proposed that metallogeny is more fundamentally driven by mechanisms for the relative generation or dissipation of the earth's internal heat energy, hence temporal thermal variations will effect plate tectonism and mineral deposition.

According to Hutchinson, mineral deposits go through evolutionary changes in composition and geological setting through time, reflecting evolutionary changes in the earth's systems. The corollary of this is that mineral deposits have become more diverse and complicated through time.

A conceptual breakthrough of sorts was provided by Barley and Groves, who suggested that there are three main controls on the evolution of mineral deposits—viz. (1) evolution of the hydrosphere and atmosphere, (2) decreasing global heat flow, and (3) long-term large-scale tectonic trends. Points (1) and (2) address the fact that certain types of mineral deposits are restricted to specific periods in earth history, e.g. (1) the Archean paleoplacer Witwatersrand (South Africa) uraninite-gold deposits and the large Proterozoic iron formations, which result from the lack of oxygen and the build-up of oxygen in the atmosphere, respectively; and (2) high temperature, high magnesium komatiite basaltic flows, and associated nickel sulfide mineralization solely in the Archean. In terms of long-term tectonic trends, Barley and Groves suggest that the cyclic aggregation and breakup of large (super) continental masses (i.e., a super Wilson cycle) control mineral deposit formation and hence metallogeny of the earth. For instance, mesothermal lode gold deposits reflect periods of intense convergent margin tectonics; conversely, in periods of more quiescent rifting/subduction when supercontinents were extant, anorogenic magmatic and sediment-hosted lead–zinc and copper deposits predominate.

Based on the strictures of plate tectonic theory, metallogeny is best described in terms of accretional, rifting, or anorogenic processes, although it could be argued that anorogenic processes are actually the products of superaccretional periods when supercontinents were present.

Other Measurements

Mineral deposits and tars associated with coal fires were analyzed by a wide variety of methods. Unglazed ceramic tiles (Stracher, 2011; Stracher et al., 2013) were successfully used to “force” coal-fire gas to nucleate orthorhombic sulfur-8 and gypsum. See the “Minerals” and “Coal Tars” sections of this chapter for the details.

In a Colorado study (Ide et al., 2011), a magnetometer was used to characterize a subsurface coal fire. A magnetometer was also used in a North Dakota study (Sternberg, 2011) to characterize a coal-fire burn site there. Magnetometer surveys are useful for high-resolution areal mapping that differentiates among previously burned, currently burning, and unburnt coal seams. Remanent magnetism revealed by these surveys; in combustion metamorphic rocks, may be useful for determining paleomagnetic field directions.

Aerial TIR of coal fires in the Powder River basin, Wyoming, utilized an automated FLIR® A320 camera mounted under the wing of an aircraft during predawn flights. Temperatures derived from the data acquired are a function of land surface emissivity. Fire area, perimeter, and temperature were estimated.

Tedlar® gas bags, made by Dupont™, was used by Stracher (2007) for collecting samples of coal-fire gas and it proved unreliable because gas chromatographic analyses revealed that the bags exchange coal-fire gas with the atmosphere. Giggenbach gas sampling bottles used by some volcanologists, made from fused silica, have not yet been used to collect samples of coal-fire gas.

Table 29.1.1 lists short-term sampling technologies used and preferred for coal-fire gas composition, temperature, and velocity measurements. Table 29.1.2 lists long-term technologies used for coal-fire gas composition and temperature measurements.

Table 29.1.1. Short-term sampling technologies.

Table 29.1.2. Long-term sampling technologies.

2.1.2 Mineral Resources Including Energy Resources of Geological Origin

Some mineral resources are shown in Fig. 2.10, but have been evaluated in monetary terms as a kind of wealth based on their short-term potential for commercial trading. In reality, the mineral resources called “depletable” are not really “used,” but transformed into other chemical forms, for which economic exploitation is less obvious. The carbon of fossil energy resources is converted into carbon dioxide, which has far fewer commercial uses (e.g., for sparkling drinking water or as a reinjection gas used to increase the recovery fraction of mining other subsurface fossil fuel deposits) than the originally extracted oil, gas, or solid coal, and which if not collected, will stay for considerable lengths of time in the atmosphere and cause increased greenhouse warming. Also mineral resources, such as metals or rare earth elements are not disappearing, but transformed and incorporated into, say, consumer goods (from window frames to computer circuits), from which they may, at the end of the product’s service life, be recovered after dismantling and disassembly and reused or recycled. Currently, many produced pieces of equipment are poorly manufactured as judged from a recycling perspective, requiring much effort to disassemble and thus inviting the less efficient melting down process of incineration, followed by a partial recycling of only those components that have not escaped as air or waterway pollution but lend themselves to separation into new primary materials for a second manufacturing cycle. Of course, using economic price setting as a guideline for recycling, the declining availability of virgin materials will eventually force an increase in recycling fraction. Still, even future insistence on products optimized for end-of-life disassembly will not allow recovery of minerals that have already been reduced to compounds spread over the environment in concentrations not inviting extraction.

Figs 2.12–2.16 show a selection of important mineral resources currently mined and mapped according to their location. The quantity of minerals at each site is not shown and is less easy to quantify than the resource extraction level that may be achieved in the next decades, eventually by exploitation of new deposits, either those already known or those that may be found in promising geological areas. Often, the geology of underground ores and composites do not allow a precise quantification of the overall resource or the economy of recovery. As always in resource estimation, there is a cut-off toward concentrations, for which recovery is considered highly uneconomical or impossible, at least with currently known extraction technology. One uses terms, such as proven reserves, possible reserves or ultimately recoverable resources to classify the estimates. The proven resources are often quite low, allowing only some 15 years of extraction at current level for minerals such as gold, silver, or lead and no more than 90 years for resources such as iron and aluminium (World Bank, 2011).

However, unlike fossil fuels, mineral resources like metals or building materials are not irrevocably depleted by their use in human society, but may as mentioned be reused or recycled. At present, recycling fractions range from under 1% (e.g., lithium or germanium) to over 50% (e.g., iron, copper, silver, gold, and platinum), as shown for the product end-of-life recycling levels in Fig. 2.17. Additional recycling options exist at the resource extraction and product manufacture levels. The global amount of minerals imbedded into buildings and other structures, vehicles, industrial equipment, and consumer goods on average works out to some 80 kg/cap. of aluminium, 45 kg/cap. of copper, 2200 kg/cap. of iron, 8 kg/cap. of lead, and 0.1 kg/cap. of silver, with the transportation sector being the primary user of aluminium, followed by the buildings and construction sectors, which are also the prime users of copper, iron, and lead, while the principal use of silver is in consumer goods, such as jewellery (UNEP, 2010). Some minerals are presently growing in importance, for example, lithium used in batteries that are currently expanding from consumer electronics to road vehicles, and this will certainly demand moving Li from the low recycling level of Fig. 2.17 to a much higher value (Mohr et al., 2012).

Whereas current mineral extraction is mostly from mines drilled into the subsoil of land areas, at the surface or deeper, there has long been an interest in offshore mining (Odell, 1997; Baturin, 1997), notably of the nodules with a high mineral content found on the bottoms of many ocean locations. However, the cost of extraction is in most cases still seen as too high. New focus with more short-term prospects has been directed at what is called ‘urban mining’, meaning extraction and recycling of mineral resources from the urban waste, which currently is increasingly being collected and separated (rather than incinerated, at the source or at a waste treatment centre) in a number of countries around the world (Zhu, 2014). A variety of recycling processes, adapted to the relevant product mix, have been developed and in many cases, and recycling rates of over 90% are available (e.g., for chromium and certain iron products; UNEP, 2011) or promised in the near future. An important example is recycling of rapidly growing amounts of scrap from electronic equipment (Tuncuk et al., 2012). For other products, such as the dominant current type of solar cells, the recycling request must be based on environmental concern because the chief material, silicon, is an abundant mineral and recycling therefore not warranted by direct economy (McDonald and Pearce, 2010).

3.3.2.4 Oil Sands

This mineral resource of unconventional fossil fuel is also known as tar sand bitumen, bitumen-rocks oil, bituminous sand, impregnated rocks, oil sands, and rock asphalt and is mostly found in the Canadian province of Alberta (Athabasca Oil Sands). It consists of a sand-like rock (mainly quartz) impregnated with bitumen and moisture. Only a weight fraction of 10–20% from rough oil sand can be extracted as crude oil (denoted as synthetic crude oil in this context).

The molecular weight of bitumen is in the range of 540–800 kg/kmol. The valuable part of oil sand is bitumen, which represents a significant supply of energy and can be separated from the sand matrix by various methods and then converted into synthetic crude oil. In Table 3.11 the main properties of bitumen from oil sand in comparison to conventional crude oil are given. As observed, the hydrogen content in bitumen is ~ 3% less by weight with respect to conventional crude oil, which shows an important hydrogen deficit from a fuel utilization point of view. This illustrates that bitumen requires processing by hydro-treating (for hydrogen addition) and/or cocking (for carbon removal). Synthetic crude oil derived from bitumen has about 32 °API and 10 cP with sulfur and nitrogen weight fractions of 0.2% and 0.1%, respectively.

Table 3.11. Average Properties of Bitumen Compared to Conventional Crude Oil

Note: TST, Tar Sand Triangle (Utah); PRS, P.R. Springs (Utah); NWAR, Northwest Asphalt Ridge (Utah).

Source: Lee et al. (2007) and Bunger et al. (1979).

According to Bunger et al. (1979) the heating value of tar sand bitumen can be estimated based on the Boie equation—Equation (3.2)—as a function of the weight fractions of carbon, hydrogen, sulfur, oxygen, and nitrogen. The average composition of tar site bitumen at four major exploitation sites in North America is listed in Table 3.11. The chemical exergy of tar sand bitumen can be estimated using Equation (3.12) on a dry ash-free basis and Equation (3.13) on a wet basis.

9.3 Coal Utilisation and Clean Coal Technologies

The MEMR released a National Coal Policy in January 2004. The aim of the policy is to provide guidance in the management, exploitation, utilisation and development of coal from 2005 to 2020. The GOI’s National Energy Policy, formulated in presidential Decree No. 5/2006 and presidential Instruction No. 2/2006 (Ministry of Mines and Energy), places increasing emphasis on coal as an energy source. Coal’s share of national primary energy production is forecast to increase from 18% in 2009 to 33% in 2025. Indonesia’s challenges include how to effectively utilise the vast resources of low rank coal in Kalimantan and Sumatera as a long-term energy source for national development whilst maintaining the valuable thermal coal export industry revenues. Figure 9.7 provides an overview of the National Coal Policy objectives.

The National Coal Policy aim is to develop the coal industry and secure coal supplies and efficient utilisation for national development. The focus is on the utilisation of Indonesia’s abundant low rank coal resources, which are positioned as a strategic energy source for Indonesia. Tax incentives for investment in low rank coal upgrading and clean coal technologies are offered under government regulations No. 1/2007 and No. 62/2008.Table 9.7 describes the R&D and operating technologies that have been or are under investigation within Indonesia for low rank coal.

Table 9.7. I ndonesian clean coal technology R&D

The MEMR drives R&D in Clean Coal technology. MEMR has an agency for R&D, known as tekMira, which has developed a Coal Centre at Palimanan in West Java. The tekMira Coal Centre Master Plan shows below facilities in operation and planning stages.

Biocoal briquette demonstration plant;

Activated carbon pilot plant;

Upgrading brown coal (UBC) pilot plant;

Foundry coke pilot plant; Hybrid coal gasification pilot plant;

Coal-water mixture pilot plant;

Cyclone burner pilot plant;

Coal gasification pilot plant;

Coal liquefaction pilot plant.

The Indonesian Agency for the Assessment and Application of Technology (BPPT) owns the national energy research centre located in Serpong Java. They manage the country’s only pilot scale coal milling and combustion test facility known by its Indonesian acronym B2TE (BalaiBesarTeknologiEnergi). This facility has completed many tests on Indonesian coals for domestic and export consumption and consists of test milling apparatus, drop tube furnace and test boiler.

9.3.1 Coal upgrading

Coal upgrading has been carried out at mainly pilot and demonstration scale in Indonesia. There are several processes that have been investigated. In the 1990s and 2000s the Japanese government was the main partner providing technical and financial support through JCoal and Japan International Cooperation Agency (JICA) to MEMR, PLN and other GOI agencies for clean coal technology, effective utilisation and industry development.

Upgrading brown coal (UBC)

tekMira in conjunction with JCoal operated a demonstration scale UBC plant in Palimanan West Java since 2003. The plant was successfully run at 5tpd rate which led to the development of a 600 tpd pilot scale plant at Satui in South Kalimantan adjacent to the Mulia Ecocoal mine, shown in Figs 9.8a and 9.8b. The process produced a 6000 kcal/kg gross as received (GAR) product from the 4200 kcal/kg GAR feedstock and a reduction in Total Moisture from 35% feed to about 10% product. Kobe Steel has successfully trialled the UBC product in Japan at pilot scale as a single product and in blends with bituminous coals (Akiyama et al., 2010).

Figure 9.8. (a) Satui UBC plant. (b) Satui UBC plant.

Binderless coal briquetting (BCB)

White Energy developed the BCB technology at pilot scale in Australia, after initial work by CSIRO. In partnership with Bayan Group, White Energy formed PT Kaltim Supa Coal, and constructed a commercial scale 1 Mtpa plant at Tabang in East Kalimantan. The BCB process takes 4200 kcal/kg GAR feed and produces a 6100 GAR product. Its difference from Kobelco’s UBC process is that BCB does not use any binder to reconstitute the dried product.

This project has been terminated due to commercial differences between the partners. The financial model used a sub-20 coal price delivered from mine mouth to plant. Bayan Group changed the price to follow the Indonesian Reference Price which more than doubles the feedstock cost. The parties are in negotiations to settle the dispute (White Energy, 2011).

This is the first commercial scale plant upgrading low rank coal in Indonesia.

Rotary drum dryer (RDD)

Some Indonesian coal companies are looking at this technology in partnership with Chinese providers. RDD removes mainly free moisture from the coal.

Coal upgrading briquetting (CUB)

PT BaktiEnergiPersada is reviewing this US developed technology. The process utilises a flash dryer to remove mainly free moisture.

Coal drying briquetting (CDB)

tekMira is developing this technology at bench scale based on a steam tube dryer. Potential application is in the tea industry to dry harvested tea leaves, as well as other small-scale agricultural and industrial plants.

X Environmental Engineering and Reclamation

Mining removes mineral resources from their natural environment, and hence by definition disturbs nature. It is the function of enviromental engineering to ensure that the impact of the mining operations on the natural environment—on land, on air, and on water, or, more generally, on the biosphere—is minimized or is maintained within acceptable limits. Mining, surface mining in particular, requires a change in land use, at least for the life of the mine. Reclamation restores land use as rapidly as possible, during or after mining, or returns the land to an environmentally acceptable condition upon completion of mining.

Effective reclamation requires that the postmining condition of the land be taken into account during mine planning, that is, that the mining operations be planned and designed with the ultimate land restoration and use as an integral part of the planning objectives. (This consideration helps explain the difficulties encountered by mines when stringent reclamation requirements are imposed or changed while they are already operating, i.e., when mining methods and plans already have been selected, mining equipment has been acquired, etc.)

The environmental impact of mining can be subdivided into the impact on land, on water, and on air. The primary air pollution resulting from mining is the generation of dust, that is, particulate matter that becomes airborne. (Sulfur emissions from coal-burning power plants or metal-ore smelters are more directly associated with the user, or customer, of the mine, than with mining itself.) The federal government and most states have enacted legislation that requires the mine operator to maintain fugitive dust within acceptable limits. Typical control procedures include extensive water spraying of haul roads, by means of special large tank trucks, of transfer (loading, unloading) points, and of storage areas. Wetting agents often are added to the water in order to improve retention efficiency.

Land reclamation is a particular concern for surface coal mining, especially strip mining which tends to disturb relatively large ares in a relatively short time. (The abandonment of unreclaimed surface coal mines, especially in Appalachia, is at least partially responsible for the enactment of strict reclamation legislation. Some of the more destructive past practices, such as conventional contour mining, have now been replaced entirely by mining methods, such as haulback mining, that allow full reclamation of the mined areas.)

Reclamation practices of necessity must differ significantly depending on local soil, topographical, and climatic conditions (e.g., revegetation in the semiarid Southwest imposes significantly different seeding, watering, feeding, and contouring requirements than in the Midwest, where precipitation usually is ample). The typical first step in reclamation is the removal and temporary storage of the top-soil, prior to mining (Figs. 4 and 5). Waste rock removed during mining is spoiled in mined-out areas. Upon completion of grading or surface recontouring, the top-soil is replaced. The restoration of the land is completed with revegetation. The latter phase usually is accomplished with the assistance, or under the direction, of agronomists and plant scientists. The major environmental impacts of underground mining include subsidence of the ground surface as a result of removing rock from the subsurface and changes in the groundwater, primarily the water table level drawdown caused by pumping water from the mine. Acidic mine drainage can result where the water is released from operating or abandoned coal or metal mines in which the rock contains sulfur. Remedial action includes water treatment, mine design to minimize releases, and mine closure and abandonment procedures engineered to eliminate long-term impacts.

Reducing environmental impact has become a major preoccupation for the mining engineer. It affects all phases of engineering, from premining impact evaluations and extensive permit applications, through mine closure. Environmental protection is a major area of research and development, both by the industry and by the federal government.

7.5.3.11 Exploration and Production Techniques

The search of mineral deposits is the first phase of the mining cycle. Applications of the GIS helps mining professionals to perform in-depth analyses, get insights into the data and make high-level decisions. Integration of GIS with CMS provides the ability to blend non-structured documents with maps in heterogeneous and geographically distributed locations and to analyze, survey, and make reports while studying maps of specific mine sites (Aysan et al., 2011). The facility to view the integrated GIS through a portal application helps improve the decision-making process across various aspects related to mining.

3.15 Mongolia

Mongolia possesses large mineral deposits which, owing to the political isolation of Mongolia during most of the 20th Century, remain largely undeveloped. Some mining operations were established prior to 1989 with the help of the Soviet Union and Eastern European countries but following the breakup of the USSR, the move by Mongolia to a free economy and the Minerals Law being passed in 1997, the potential is being recognized.

Numbered among the indigenous minerals are oil shale deposits from the Lower Cretaceous Dsunbayan Group, located in the east of the country. Exploration and investigation of the deposits began as long ago as 1930 but it was only during the 1990s and with the help of Japanese organizations that detailed analyses began. Twenty six deposits were studied and found to be associated with coal measures. During 2004, Narantuul Trade Company, the owner of the Eidemt deposit was investigating the possibilities of developing the potential of the field with the aid of international cooperation. It was reported in late-2006 that China University of Petroleum had signed a contract to undertake a feasibility study on the Khoot oil shale deposit.

7.2.3.6 Poland

The most important mineral resource in Poland is hard coal (mainly located in Upper Silesia and the Lublin coal basins), being the ninth largest hard coal producer and the largest one in the EU. Besides, Poland also has significant deposits of lignite, located in Turoszow, Konin, and Belchatów (Mills, 2016). Therefore, coal plays a major role in Poland's energy security, providing the reliable and affordable energy supply that is fundamental to Poland's economic stability and ongoing development, as 85%–90% of the electricity and heat generated in Poland is produced from local coal (Gawlik and Mokrzycki, 2016; Sobolewski, 2016).

Based on the new technology developed by the “Institute for Chemical Processing of Coal”, a new coal gasification project has been proposed by Grupa Azoty. The project was approved by the Polish government in June 2015, and the start date is expected to be 2020–21 (Sciazko et al., 2014; Skoupka and Sciazko, 2016; Sobolewski, 2016; Sobolewski et al., 2015; SourceWatch, 2015).

As in many other countries, in addition to IGCC technologies, another approach studied in Poland to coal gasification process is underground coal gasification (UCG). Some interesting works have been carried out by the GIG's Clean Coal Technology Centre (Glówny Instytut Górnictwa, translated as “Central Mining Institute”), both in Katowice and Mikolów, to finally conduct a pilot test in the operated mine KWK Wieczorek. After a 3-month trial, the results have been very promising and, consequently, a technological project of UCG demonstration installation has been proposed (Stańczyk, 2015, 2016; Stańczyk et al., 2015).

9.1.1 General considerations of the effects of underground mining on subsurface rock deformation and subsidence

Rock overlying a mineral deposit is in a state of natural equilibrium. Unsupported mine voids created during underground mining cause a disequilibrium in rocks, leading to their displacement and deformation. Rock displacement that occurs in the vicinity of an underground mine working extends upward to the upper layers of the overburden. Once the underground working reaches a sufficiently large size, the displacement of rock strata will extend to the ground surface, which will in turn undergo deformation. As early as the mid-19th century, subsidence began to cause severe damage to buildings, facilities, transportation links, and agricultural land in a number of European coalfields. This led coal mine surveyors to install monitoring stations and conduct systematic monitoring of subsurface rock deformation and subsidence. Based on the summary of the results of this monitoring and theoretical understanding, a new subfield was formed within mining science—rock deformation.

Rock deformation and subsidence during underground mining developments of coalfields are among the most extensively investigated processes. Therefore, the presentation of material will be based primarily on the results of studies conducted in the coal-mining regions of the Commonwealth of Independent States (CIS).

In underground coal gasification, the immediate roof strata not only undergo displacement and deformation involving a loss of continuity but also change their mechanical properties, chemical, and mineralogical composition and its aggregate state. This results in a loss of integrity of the underground UCG gasifier cavity, increased losses of oxygen supply (injected air) and gasifier gas losses, and a heat loss to the surrounding strata, with some peripheral process air leakage occurring that can disrupt the entire UCG plant process.

Technological process parameters and the specifics of a coal-mining operation determine the shape of the depleted UCG cavity and the nature of overburden deformation, which in turn have a direct impact on process consistency and stability and on process performance and economic sustainability. It is for this reason that monitoring and research into rock deformation and subsidence during underground coal gasification and conventional underground coal mining is of great importance not only for prediction of the undermining of surface structures and their protection but also for the continued improvement of these methodologies.

As research results showed, the principal processes of rock deformation during UCG or conventional shaft mining of coal are driven by a common set of mechanisms. It is therefore useful to begin by considering the general principles that were identified in relation to conventional coal-mining settings.