Coal washability assessment based on sink–float tests and image-based RGB-HSV analysis

Study on dry separation technology of a continuous gas-solid separation fluidized bed with a moving scraper (И) – Separation performance

ABSTRACTThe use of low-rank coals as an energy source may cause environmental problems. Washability of a Turkish lignite sample was evaluated by conventional methods with sink-and-float tests and a Reichert spiral. Also, the fine size fractions were cleaned with enhanced gravity separation techniques, a multigravity separator (MGS), and a Falcon concentrator. The as-received lignite sample was sieved into five size fractions (-100 +25.4 mm; -25.4 +12.7 mm; -12.7 +1.2 mm; -1.2 +0.15 mm; -0.15 mm) and the washability characteristics of the first three fractions were separately investigated with sink-float tests. The -1.2 +0.15 mm size fraction was cleaned using a Reichert spiral. Tests with the MGS and the Falcon concentrator were conducted with a -0.15 mm fine size fraction. Sink-float tests results showed that the tested coal can be classified as difficult-to-clean coal due to the presence of high near-gravity material at lower separation densities than 1.7 g/cm3. However, the production of cleaner coal was easier at finer size fractions due to further liberation. Enhanced gravity separation techniques presented better results in terms of combustible recoveries.

Washability analysis is the basis for nearly all coal preparation plant separations. Unfortunately, there are no on-line techniques for determining this most fundamental of all coal cleaning information. In light of recent successes at the University of Utah, it now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. The successful development of such a device is critical to the establishment of process control and automated coal blending systems. In this regard, Virginia Tech, Terra Tek Inc., and Cyprus-Amax Coal Company have joined with the University of Utah and agreed to undertake the development of an x-ray CT-based on-line coal washability analyzer with financial assistance from DOE. The three-year project will cost $594,571, of which 33% ($194,575) will be cost-shared by the participants. The project will involve development of appropriate software and extensive testing/evaluation of well- characterized coal samples from three coal preparation plants. Each project participant brings special expertise to the project which is expected to create a new dimension in coal cleaning technology. Finally, it should be noted that the analyzer may prove to be a universal analyzer capable of providing not only washability analysis, but also particle size distribution analysis, ash analysis and perhaps pyritic sulfur analysis.

Washability analysis is the basis for nearly all coal preparation plant separations. Unfortunately, there are no on-line techniques for determining this most fundamental of all coal cleaning information. In light of recent successes at the University of Utah, it now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. The successful development of such a device is critical to the establishment of process control and automated coal blending systems. In this regard, Virginia Tech, Terra Tek Inc., and Cyprus-Amax Coal Company have joined with the University of Utah and agreed to undertake the development of a x-ray CT-based on-line coal washability analyzer with financial assistance from DOE. The three-year project will cost $594,571, of which 33% ($194,575) will be cost-shared by the participants. The project will involve development of appropriate software and extensive testing/evaluation of well-characterized coal samples from three coal preparation plants. Each project participant brings special expertise to the project which is expected to create a new dimension in coal cleaning technology. Finally, it should be noted that the analyzer may prove to be a universal analyzer capable of providing not only washability analysis, but also particle size distribution analysis, ash analysis and perhaps pyritic sulfur analysis.

The extent of coal cleaning is primarily dependent on three core factors: (1) coal liberation, (2) coal washability, and (3) separator performance. The most important factor that determines the extent of coal cleaning is the liberation of organic matter from mineral matter. In the past, various methods for estimating coal liberation characteristics have been used by different researchers such as fractionation method, macroscopic and microscopic techniques, advanced image analysis techniques, and methods based on float-sink data of coal. Some of these methods do not precisely represent coal liberation, some are purely qualitative, and some involve expensive equipment, extensive testing, and cumbersome mathematical analysis. Moreover, other than float-sink analysis, these techniques are not applicable to the original coal size range being treated in a coal preparation plant. This paper presents a critical review of previous work related to the assessment of coal liberation and proposes a simple mathematical expression for quantifying coal liberation characteristics. The proposed method is exclusively based on float-sink data and thus applicable to any coal size range being treated in gravity-based separators. The proposed method was applied to estimate and compare liberation characteristics of coals belonging to different countries of the world by using their published float-sink data.

Washability analysis is the basis for nearly all coal preparation plant separations. Unfortunately, there are no on-line techniques for determining this most fundamental of all coal cleaning information. In light of recent successes at the University of Utah, it now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. The successful development of such a device is critical to the establishment of process control and automated coal blending systems. In this regard, Virginia Tech, Terra Tek Inc., and several eastern coal companies have joined with the University of Utah and agreed to undertake the development of a x-ray CT-based on-line coal washability analyzer with financial assistance from DOE. The three-year project will cost $594,571, of which 33% ($194,575) will be cost-shared by the participants. The project involves development of appropriate software and extensive testing/evaluation of well-characterized coal samples from operating coal preparation plants. Each project participant brings special expertise to the project which is expected to create a new dimension in coal cleaning technology. Finally, it should be noted that the analyzer may prove to be a universal analyzer capable of providing not only washability analysis, but also particle size distribution analysis, ash analysis and perhaps pyritic sulfur analysis.

Washability analysis is the basis for nearly all coal preparation plant separations. Unfortunately, there are no on-line techniques for determining this most fundamental of all coal cleaning information. In light of recent successes at the University of Utah, it now appears possible to determine coal washability on-line through the use of x-ray computed tomography (CT) analysis. The successful development of such a device is critical to the establishment of process control and automated coal blending systems. In this regard, Virginia Tech, Terra Tek Inc., and several eastern coal companies have joined with the University of Utah and agreed to undertake the development of a x-ray CT-based on-line coal washability analyzer with financial assistance from DOE. The three-year project will cost $594,571, of which 33% ($194,575) will be cost-shared by the participants. The project involves development of appropriate software and extensive testing/evaluation of well-characterized coal samples from operating coal preparation plants. Each project participant brings special expertise to the project which is expected to create a new dimension in coal cleaning technology. Finally, it should be noted that the analyzer may prove to be a universal analyzer capable of providing not only washability analysis, but also particle size distribution analysis, ash analysis and perhaps pyritic sulfur analysis.

Greece has mineral resources in which strategic elements such as nickel (Ni) and cobalt (Co) are present. In this study, characterizations of the metal concentrations of three laterite deposits, as well as minerals from a kiln originating from a mineral processing plant, were carried out. The aim of this research was to integrate technological characterization data on the quantities of cobalt (Co) and nickel (Ni) present in the lateritic profiles of three mineral deposits from Greece and in kiln dust. The study was conducted at the Mineral Processing Laboratory of UPC/Bases Manresa. Aliquots were constituted for particle-size distribution tests by wet sieving followed by laser granulometry. Scanning electron microscopy (SEM) was used to determine the mineralogical compositions. Sink–float tests were conducted to estimate the particle liberation. Mineral liberation analysis (MLA) was performed to understand the liberation and the association of minerals in the samples.

This article presents the results of analysis of the hazards posed by coal mine dust and methane in the coal preparation plants of hard coal mines in Poland. It was shown how the number of workplaces in plants at risk of coal dust explosion and the highest permissible dust concentration changed in the period from 2003 to 2022 when compared with coal production. The methodology of assessing mine dust hazards was based on hazard ratios related to one million tons of hard coal enriched in preparation plants. As a result of the analysis, it was found that the explosion hazard index with zone 20 showed an increasing trend in the analyzed period, while the explosion hazard indices with zones 21 and 22 analyzed together and the maximum permissible dust concentration showed decreasing trends following a decrease in hard coal production. In the case of methane, no zone 0 explosion hazards were found, and there were only a few instances of zone 1 explosion hazards. However, it was determined that the explosion hazard index for zone 2 showed an increasing trend during the analyzed period, which is directly proportional to the coal produced and is a result of increasing depth of mining.

Coal cleaning is listed among the methods of mercury emissions reduction from the point of view of coal utilisation processes. The article quantifies the content of mercury in Polish hard steam coals, the charge of mercury and, for around 20 Polish Coal Preparation Plants (CPP), the split of mercury charge in raw coals between commercial coal products and waste. The mean mercury content in Polish hard steam coal is presented also. The differences between the washability (in terms of mercury behaviour) of different size fraction of raw coal are discussed and emphasized. Coal cleaning, giving us the benefit of cleaner fuel production, is accompanied by waste release. Waste from coal cleaning may be regarded as one of the sources of the release of mercury to the environment, what wasn’t the object of in-depth analyses so far. The annual charge of mercury in waste from hard steam coal cleaning in Poland was assessed and emissions of mercury from waste dumps as well as the increase of the mercury concentration in the surrounding soils are discussed.

Coal slime water treatment is a very important process in coal preparation plant, its treatment effect directly affects the reuse of washing water and closed-circuit circulation index, and on the other links of coal preparation plant such as separation efficiency, the number of product quality index has a great impact, and even restricts the economic and social benefits of an important system. Based on improved grey prediction fuzzy control principle, an improved slurry flocculating settling process of feed forward and feedback control strategy, the improvement is: using fuzzy algorithm to replace the current use of conventional fuzzy control algorithm, namely according to the online setting parameters of fuzzy rules, both to overcome the difficult to eliminate the steady-state error and fuzzy control to realize accurate control weaknesses, and overcome the difficulty of parameter setting, make them form a complementary advantages. Therefore, it is of great significance to study advanced control method and improve control effect in coal preparation plant.

The extent of coal cleaning is primarily dependent upon three core factors; (1) coal liberation, (2) coal washability, and (3) separator performance. The first factor has been dealt with in part 1. This part focuses on the second and third core factors. Coal washability data are typically generated by the standard float-sink test. Many researchers have proposed different washability indices based on float-sink data to describe coal amenability to washing, but most of these involve cumbersome mathematical calculations while relying on an error-prone graphical technique. Probable error (Ep) is generally used to represent coal separator efficiency but its calculation requires float-sink analysis of both feed and separator products. This paper proposes a simple equation for quantitative estimation of the degree of coal washing based on the feed coal washability data, clean coal yield, and ash. The proposed equation was applied to quantify and compare the washability characteristics of coals from different countries and provides an alternative method for measuring separator efficiency (in percentage).

This paper summarizes the results of determination of the washability characteristics of anthracite coal from Vrska Cuka coal mine, Serbia. The effect of different coal size fractions has been studied through washability studies. In this study, float-sink experiments were carried out with the anthracite coal samples on (−19 + 9.5) mm, (−9.5 + 4.75) mm, (−4.75 + 2.36) mm, and (−2.36 + 0.6) mm size fractions. Two washability parameters, Index of Washability (IW) and Near Gravity Material Index (NGMI), were calculated and the results were compared. The IW and NGMI values indicated that the washability of different size fractions of anthracite coal was easy to relatively difficult to wash. The obtained values of IW showed that the order of coal washing ability by size fractions was as follows: (−9.5 + 4.75) mm, (−4.75 + 2.36) mm, (−2.36 + 0.6) mm, and (−19 + 9.5) mm. The NGMI values decreased with increasing specific gravity and decreasing particle size fractions. The minimum values of NGMI were achieved at density of 1650 kg/m3 and these values were 0.1322, 0.0695, 0.0677, and 0.0240, respectively. The results presented in this study indicate that washability of the anthracite coal is relatively easy and should be washed at a specific density of 1650 kg/m3.

This Mine Safety and Health Administration (MSHA) report reviews in detail accident, injury, and illness experience in the anthracite and bituminous coal industries of the United States for 1976. Fifty-seven tables summarize the reported work injuries by work location, principal cause of injury, degree of injury, part of body injured, and nature of injury, and contain correlative information on employment, worktime, and operating activity. Concise historical information is presented in nine tables. Under provisions of Section III, Public Law 91-173, Federal Coal Mine Health and Safety Act of 1969, the Mining Enforcement and Safety Administration collects accident, injury, illness, employment, and production data for anthracite and bituminous coal mines and preparation plants in the United States by a mandatory reporting system.

The lower and upper coal seams of the Candiota Coalfield, Brazil — Geological setting, petrological and chemical characterization, and studies on reactivity and beneficiation related to their combustion potential