Coal Agglomeration Research Articles

The investigation of coal–pyrite/lignite concentration and their separation in the artificial mixture by oil agglomeration

In this study, the concentration of coal–pyrite and lignite taken from Yozgat-Ayridam (Turkey) Coal Management was investigated by oil agglomeration. In the previous studies, the agglomeration of coal–pyrite was investigated using different bridging liquids (fuel oil, diesel oil and kerosene) and the combination of reagent (KEX, Acorga M5397)+kerosene. When using only bridging liquids, the agglomeration recovery of pyrite was very low. To increase the hydrophobicity of pyrite, KEX was used. However, the pyrite was not agglomerated with an acceptable recovery. But when using Acorga M5397, which is a chelating reagent, the agglomeration recovery of pyrite was increased. The pyrite was agglomerated with a recovery of 76.70 wt% by single-stage agglomeration. In the optimum conditions which were determined for coal–pyrite, the agglomeration recovery of lignite was investigated. It was found that the lignite could not be agglomerated with an acceptable recovery. To investigate the separation of coal–pyrite and lignite, the artificial mixture of coal–pyrite and lignite was prepared with the weight ratio of 1/4 of coal–pyrite and lignite. It was found that the pyrite could be agglomerated at a recovery of 96.54% with three-stage agglomeration process. The lignite concentrate was produced with a recovery of 73.96 wt% and the pyrite content of 0.86 wt%. These findings showed that the coal–pyrite and lignite could be separated by oil agglomeration using appropriate reagent and bridging liquid.

Preparation and characterization of spherical activated carbons from oil agglomerated bituminous coals for removing organic impurities from water

A new and simple method of producing of spherical activated carbons (SACs) from different bituminous coals, i.e., gas coal, gas-coking coal and orthocoking coal, is presented. Coal agglomerates of spherical shape obtained by oil agglomeration using rapeseed oil and linseed oil, were subjected to carbonization and activation with steam at 850 °C. The SACs prepared from gas-coking coal (hvAb) agglomerates were characterized by the best developed porous structure with surface area S BET of about 800 m 2/g and pore volume of 0.40 cm 3/g. The adsorption capacity of the produced SACs was determined in terms of substituted phenolic compounds. The adsorption of 2-chlorophenol (OCP), 4-chlorophenol (PCP) and 4-nitrophenol (PNP) from aqueous solutions was studied under a static conditions on the SAC prepared from gas-coking coal agglomerated using rapeseed oil. At high concentrations of the solute the adsorption behavior of OCP was found to be different in comparison to PCP and PNP. The adsorption of the two last phenolic compounds on the selected SAC is very well described by Langmuir adsorption model. For OCP a two-stepped adsorption isotherm was obtained. The Langmuir isotherm equation fits very well only for the first stage of the OCP adsorption.

石炭の水中造粒への毛管吸引圧の影響

The effect of capillary suction potential on the agglomeration of coal in water was investigated at various concentrations of added surface active agent and addition ratios of bridging liquid. Agglomeration was carried out by injecting castor oil as a bridging liquid into the suspension, which consisted of disperse medium and ground coal. An aqueous solution of 10-2 mol · l-1-NaCl was used as the disperse medium, and sodium oleate was added to the solution as an additive surface active agent. The main results of this work are as follows:1) The addition of sodium oleate to the disperse medium modified both the contact angle of the bridging liquid on coal particles and the interfacial tension between the bridging liquid and the disperse medium and therefore affected the agglomeration phenomena.2) The equilibrium agglomerate diameter increased as the capillary suction potential increased. Based on a model in which the equilibrium agglomerate diameter is determined by the balance between the cohesive force caused by capillary suction potential and the destructive force caused by agitation, an empirical equation to determine relationship between the equilibrium agglomerate diameter and the cohesive force was obtained.

Coal Agglomeration with Microbubbles

Coal cleaning by selective agglomeration of an aqueous suspension of coal particles was demonstrated on a laboratory scale by employing a colloidal dispersion of microscopic gas bubbles as an agglomerant. The microbubbles were produced by saturating water with gas under pressure and then releasing the pressure as the water was agitated. The formation and stabilization of microbubbles was facilitated by employing a small amount of i-octane. Agglomeration was carried out in a closed system using a high shear rate and with no additional air present. The resulting agglomerates Boated readily since they consisted of a mixture of coal particles and microbubbles. Therefore, the agglomerates were recovered by allowing the treated material to separate into distinct layers under quiescent conditions. The upper product layer held most of the coal with greatly diminished ash content while the bottom layer was composed largely of ash-forming mineral matter. The effects of various process parameters were studied including solids concentration, i-octane concentration, and air saturation pressure. In addition, the results achieved with two agglomeration stages were compared with the results of a single stage.

Use of vegetable oils and fatty acid methyl esters in the production of spherical activated carbons

The possibility of using vegetable oils, i.e., rapeseed oil, soybean oil, linseed oil, tung oil, castor oil and dehydroxylated castor oil, and the fatty acid methyl esters (FAMEs) obtained from them, for the agglomeration of bituminous coals was investigated. Both vegetable oils and FAMEs were found to be suitable bridging liquids for the production of spherical agglomerates-precursor of spherical activated carbons. By replacing the petroleum and coal derivatives commonly used in coal granulation with liquids of natural origin the environmental nuisance in the production of activated carbon can be reduced. Coal agglomerates produced using vegetable oils and FAME, and subjected to carbonisation and activation with steam became spherical activated carbons characterised by well-developed porous structures, marked mechanical strength, and good sorption properties determined by the standard tests of methylene blue and iodine adsorption from aqueous solutions.

00/01249 Flow characteristics of coal-oil-water mixture prepared by disintegration of deashed coal agglomerates

00/01249 Flow characteristics of coal-oil-water mixture prepared by disintegration of deashed coal agglomerates

99/02723 Application of coal gold agglomeration process to gold recovering from amalgamation talling

99/02723 Application of coal gold agglomeration process to gold recovering from amalgamation talling

Application of Flow Consecutor for coal upgrading

One of the coal upgrading methods is selective coal agglomeration. The agglomeration process traditionally is performed in the stirred tanks and, because of its disadvantages, is not popular. To make the technology economically and technically more attractive, the stirred tanks can be replaced by a simple Flow Consecutor (FC). The results of the laboratory scale tests with Illinois, Kentucky, Upper Freeport and Pittsburgh coals showed that replacement of stirred tanks with the FC is feasible and ensures the performance indices of the upgrading process equally good as indices for stirred tanks. However, the FC technology consumes less energy and can perform in a very compact equipment, which is suitable for a mobile plant application.

Change in Power Number of Agitating Impeller at Phase Inversion in Wet Spherical Agglomeration of Coal.

In wet spherical agglomeration, rapid progress in the agglomeration process occurs at an almost definite elapsed time after the beginning of the agglomeration operation according to the agglomeration conditions. This rapid progress in the agglomeration process is called phase inversion, and at this point the power number of the impeller agitating the suspension in the agglomeration tank is also known to increase rapidly. In this paper, we report our experimental investigation of the cause of the increase in the power number of the agitating impeller at phase inversion of wet spherical agglomeration of coal. The power number after phase inversion is 1.3-1.5 times that before phase inversion. At phase inversion, the agglomerate diameter increases rapidly, and the bulk volume of the agglomerates in the suspension also increases. The increase in these values greatly influences the increase in the power number at phase inversion.

脱灰石炭造粒粒子の解砕による石炭‐重油‐水混合物の静置安定性

The static stability of COW (Coal-Oil-Water Mixture), which is made by the disintegration of leashed coal agglomerates, is investigated. The static stability is evaluated by two methods, that is, the direct measurement of coal volume fraction in COW and the rod penetration test. When the static stability of COW is high, the difference of coal volume fraction between the upper section and the lower section of the storage column is small, and the 50% diameters of coal particles in both sections are almost equal in size. On the other hand, when the static stability of COW is low, the coal volume fraction becomes large in the lower section, and in contrast the water volume fraction becomes large in the upper section. It is found that the rod penetration test only shows whether the hardpack layer of coal particles is formed on the column bottom. An empirical equation, which represents the degree of the static stability of COW, is obtained.

98/02695 Role of fine-coal classification efficiency on coal preparation plant performance: Firth, D. A. et al. Miner. Metall. Process., 1997, 14, (1), 1–6.

The aim of this work was to study the feasibility of using vegetable oils for coal agglomeration. Three Spanish anthracites were agglomerated with refined sunflower and soybean oils. The response of coals to agglomeration with these oils was evaluated by measuring the percentages of organic matter recovery and ash and pyritic sulfur rejections. The influence of oil type and concentration on agglomeration results was investigated. In addition, results were compared with those previously obtained in the agglomeration of these coals with n-heptane. It can be concluded that refined sunflower and soybean oils are suitable for use as agglomerants for these high-rank coals, especially to clean those coals with a high content of mineral matter.

98/01872 Selective oil agglomeration of Lafia coal, Nigeria : Uwadiale, G. G. O. O. Trans. Soc. Min., Metall., Explor., 1996 (Pub. 1997), 300, 179–180

98/01872 Selective oil agglomeration of Lafia coal, Nigeria : Uwadiale, G. G. O. O. Trans. Soc. Min., Metall., Explor., 1996 (Pub. 1997), 300, 179–180

Liquid bridge rupture distance criterion between spheres

In spherical agglomeration of coal, oil-extended flotation of minerals and other fields such as sintering, particles may aggregate through the formation of a liquid bridge between them. The stability of the bridge is important to the mechanical strength of the aggregate. In this paper, work on the stability of liquid bridges between spheres is reviewed and a criterion for liquid bridge rupture distance is proposed. The novelty of the present criterion is the elimination of the necessity of solving the Laplace–Young equation, a very complicated process necessary for determining rupture distance in most existing criteria. Furthermore, in calculating the rupture distance, the present criterion simultaneously gives the neck radius of the bridge which is important in some cases. The prediction by this criterion is in good agreement with that by the Lian et al. criterion and shows a longer rupture distance than the Rayleigh criterion predicts. Comparison is made between the calculated rupture distances and experimental results for two different systems and good agreement is found.

98/01027 Improving of coking properties of coal blends with products of liquefaction of brown coal: Malkova, V. V. et al. DGMK Tagungsber., 1997, 9703 (Proceedings ICCS '97, volume 2), 865–868

In terms of transforming the energetic usage to the material usage of low-rank coals, the production of lump coke is a promising perspective. Therefore, two essential steps are necessary: Firstly, the processing and agglomeration of the non-caking coal is highly important, since they do not offer any baking capacity and thus the reachable quality of the coke is mainly set by the briquette quality. Secondly, to obtain high quality cokes the briquettes need to be coked using a well-adapted heating regime to ensure the gentle degassing of volatile matter with a minimum weakening of the briquette structure. The brown coal high temperature technology (BHT technology) developed in 1952 by Rammler and Bilkenroth was a milestone in coal conversion for brown coal but the coke strength was limited at that time. In current systematic studies, the lump coke quality of Lusatian brown coal and Indonesian brown coal was investigated varying the processing, briquetting and heating regime in laboratory scale. Those investigations should lead to a new processing and agglomeration technology to create lump coke from non-caking coals. The experiments varying the processing parameters of the coal showed that the briquetting of pre-granulated coal or pellets from a modified flat die press achieve the highest increase in briquette and coke quality. In the second step, the heating regime during pyrolysis was investigated. The results show, that the highest coke quality may be achieved using the Vollmaier regime. However, a single-stage heating regime with a heating rate of 2.85 K min−1 shows promising results as well.

98/00089 Use of coke tar for spherical agglomeration of coal

98/00089 Use of coke tar for spherical agglomeration of coal

脱灰石炭造粒粒子の解砕による石炭‐重油‐水混合物の流動特性

The flow characteristics of coal-oil-water mixture (COW) was investigated. COW was prepared by a disintegration of deashed coal agglomerates, which were obtained by the oil agglomeration of coal. When the volume fraction of dispersed waterdrops in COW was smaller than 0.2, the dispersed waterdrops influenced the flow characteristics of COW to the same extent as the dispersed coal particles. COW behaved as Bingham fluid. Both the yield value and Bingham viscosity increased with increasing total disperse phase volume fraction in COW, and with decreasing temperature. The relative viscosity of COW was well correlated by the equation derived with reference to Mooney's equation.

97/03546 Fiber reinforcement of coal logs

The Coal Log Pipeline (CLP) is a novel technology based on the concept that coal ran be compacted into circular cylinders (coal logs), and transported by water or slurry flowing through an underground pipe. There are many advantages of the Coal Log Pipeline. Since 1992, the CLP technology has been the subject of intensive research and development at the Capsule Pipeline Research Center (CPRC), University of Missouri, Columbia. Many detailed studies have been accomplished in these years and the CLP technology is rapidly approaching commercialization. The commercial applications of the CLP depend, to a large extent, on the ability of coal logs to sustain limited wear and damage during pipeline transportation over a long distance. Therefore, a most important task for the development of the CLP is to develop economical processes that produce high strength, wear-resistant coal logs. The researchers at the CPRC have completed extensive research on the coal log manufacturing processes. Two main methods of coal agglomeration have been investigated: extrusion and compaction. Many promising processes of coal log fabrication have been developed and documented to facilitate the commercialization of the CLP technology. The purpose of this research is to determine whether adding a small amount of low-cost,more » combustible fiber can improve the wear resistance of coal logs. For this purpose, a review of literature concerning the fiber reinforcement of brittle materials was conducted first; Then the effect of fiber reinforcement of coal log on its wear resistance was studied. The results from this study showed that coal log wear resistant capability was increased to some extent under some compaction conditions.« less

97/02537 Recovery of fine coal from coal preparation plants and tailings ponds by selective oil agglomeration

Environmental pressures are mounting over the practice of washery rejects disposal in tailings ponds and it is also recognized that reject fines are a valuable source of coal. Oil agglomeration has always been a potential candidate for fine coal recovery, but it has failed to see widespread use in the past, due mainly to the high cost of the oil. A hitherto unutilized source of low cost rejects oil was used successfully as an agglomerating agent in laboratory studies and favorable economics have been demonstrated. High yields of reduced ash coal have been obtained, with low oil to coal loadings. The oil is abundant, low in sulfur, ash and heavy metals, and has a low toxicity. Effective utilization of the oil required the development of a suitable emulsion chemistry, capable of handling the changing properties of the various feeds (thickener feed, thickener underflow and tailings pond). With successful development of the process in the laboratory, a PDU scale up followed, incorporating a number of novel ideas. Inclusion of an aeration technique enhanced flotation, allowed higher coal yields and facilitated the removal of water and mineral matter from the coal agglomerates. A pilot plant of two tonnes per hour is beingmore » installed in a coal washery located in Nth Western NSW, based upon the laboratory and PDU studies. There are two coal sources, one an underground coal seam and the other an open cut. Reject fines from both these sources will undergo processing in the agglomeration plant, as well as material from a large tailings pond. The laboratory studies, PDU studies and pilot plant will be discussed and an economic assessment of the PDU presented.« less

97/00059 Surface thermodynamic theory of the oil agglomeration of coals

97/00059 Surface thermodynamic theory of the oil agglomeration of coals

Selective oil agglomeration of Lafia coal, Nigeria

Because mineral matter is finely distributed within the matrix, Nigerian Lafia coal is nonresponsive to conventional processing techniques. However, testing has shown that Lafia coal can he upgraded by selective oil agglomeration. The optimum oil concentration was found to be 10 mL of paraffin per 25 g of coal. A product containing 6% ash and 1.9% sulfur was obtained with a yield of 90%. Optimum results were achieved with a grinding time of from 2.5 and 3 hrs, which produced a 98% −400 mesh product. However, further grinding was found to be deleterious to the process. Also, high pH adversely affected concentrate yields. Utilizing kerosene as a bridging liquid, a product containing 4% ash and 0.33% sulfur was achieved at a natural pH of 6.3 with a yield of 85%. At pH 9 and 10, a product containing 4.5% ash was achieved with a yield of >90%.