Coal Collector Research Articles

Adsorption of Multi-Collector on Long-Flame Coal Surface via Density Functional Theory Calculation and Molecular Dynamics Simulation

The quantum chemical properties of long-flame coal (LFC) and collectors (kerosene, diesel, diethyl phthalate (DEP), biodiesel collector (BDC), and emulsified biodiesel collector (EBDC)) were analyzed via the density functional theory (DFT). The molecular dynamics (MD) of the coal–collector–water system and the adsorption of collectors on LFC were conducted based on the first principles. The results showed that the frontier molecular orbitals of kerosene, diesel, DEP, and BDC were 0.38 eV, 0.28 eV, 0.27 eV, and 0.20 eV, respectively. The chemical reactivity order of the above mentioned collectors was BDC > DEP > diesel > kerosene. Kerosene, diesel, and DEP adsorbed with carbonyl, hydroxyl, and carboxyl groups in LFC, respectively. Carboxyl groups in BDC and carboxyl groups in LFC bilaterally adsorbed, while BDC repelled water molecules via hydrogen bonds on the LFC surface. In the systems of BDC and EBDC, the diffusion coefficients of a water molecule were 2.83 × 10−4 cm2/s and 3.73 × 10−4 cm2/s. The emulsifier that adsorbed onto the oil–water interface of the coal–BDC–water system improved the dispersion of BDC during flotation, while at the same time increasing the number of hydrogen bonds between BDC and LFC, which accelerated the migration of water molecules from the LFC surface.

Problematics in the Case of Bribery of State Officials in the Case of Illegal Mining (Ismail Bolong)

There are many definitions of unlawful acts, some call unlawful acts as violations of the law, as acts that violate the rights of others. The purpose of the research conducted was to solve the problem of bribery cases of state officials in illegal mining cases. The research method used is The research approach that researchers use is the Legal-Live Case Study approach. The results of the research conducted were based on the author's research in the field, Ismail Bolon's statement stated that he was a coal miner in Malangayu District, Kutai Katanegara (Kuka) Regency because he admitted his own actions as a coal collector and was suspected of bribing a police officer. This happened because of the weak enforcement of Article 158 of Law Number 4 of 2009 concerning Mineral and Coal Mining. Based on the author's research in the field, Ismail Bolon's statement stated that he was a coal miner in Malangayu District, Kutai Katanegara (Kuka) Regency, for admitting his own actions as a coal collector and allegedly bribing a police officer. This happened because of the weak enforcement of Article 158 of Law Number 4 of 2009 concerning Mineral and Coal Mining. The conclusion of the research conducted by the monitoring of the illegal mining process in the East Kalimantan region is still weak considering that there are dozens or even hundreds of illegal mines operating and it is suspected that there are law enforcement personnel who own this business and are involved

Performance of used lubricating oil as flotation collector for the recovery of clean low-rank coal

In this study, the possibility of used lubricating oil (ULO) as a collector to float low-rank coal was explored; a traditional coal collector, diesel oil (DO), was used for possible comparisons. Experimental measurements including Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry, and zeta potential were used to determine the chemical constituents of the collectors. Flotation tests were conducted to investigate the flotability, flotation rate, and flotation selectivity. The coal-water, coal-collector, and coal-bubble interactions were emphatically analyzed using X-ray photoelectron spectroscopy, water contact angle, coal-water-collector contact angle, and the designed particle-bubble wrap angle experiment. The results indicate that ULO contains more oxygenated functional groups, aromatic groups, and long-chain hydrocarbons than DO, leading to its strong interaction with low-rank coal. A significant increase in zeta potential was also observed in the ULO environment, which could decrease the repulsion between particles. Flotation results confirm that ULO can significantly enhance the clean coal yield and flotation rate, and present high flotation selectivity. Furthermore, the mechanism of ULO as a flotation collector was examined. The adsorption of ULO increased the carbon content and decreased the oxygen content on the low-rank coal surface. This is beneficial as it helps to decrease coal-water interaction. Meanwhile, ULO showed stronger interaction with the coal, and coal particles pretreated with ULO more easily adhere to the bubble surface. The application of ULO can promote low-rank coal flotation, and has an important role in saving coal resources and alleviating the impact of used oil on the environment.

INVESTIGATION OF PROPERTIES OF CURRENT COLLECTOR ELEMENTS AND THEIR EFFECT ON THE PERFORMANCE OF TRIBOSYSTEM «CONTACT WIRE - CURRENT COLLECTOR ELEMENT»

Purpose. The paper is devoted to the detailed analysis of interrelations at the contact point of friction pair «contact wire – current collector insert». In the work it is necessary: 1) to examine quality of manufacturing of specimens of current collector elements from different manufacturers; 2) to narrow the range of hardness for carbon inserts; 3) to develop a technique of sorting carbon current collector inserts for the structural parameters. Methodology. The executed work was based on the use of the theory of reliability of technical systems and electromechanical processes. Findings. The paper studies the interrelation at the contact point of friction pair «contact wire – current col lector insert», the connection was established between the hardness and electrical resistivity. It is proposed to narrow the range of carbon inserts hardness. The method of sorting coal collector inserts in hardness was developed, and the research has revealed the discrepancy of current collector inserts with existing regulations. It was proposed to equip the pantographs slide with current collector elements using special scheme and to develop a specialized research facility, which will be possible to conduct studies of the interaction of the friction pair «contact wire – current collector insert». Originality. In the course of the study the current collector inserts the sharp structural heterogeneity and fluctuations of the density of the material along the length of the insert were established. The dependence between hardness of inserts and electrical resistivity was established. It was analyzed and concluded about the need to reduce the values of the normal range of hardness. Based on the results of the research, the experimental dependences were obtained and proposed the method for sorting carbon current collector inserts for the structural parameters. Practical value. The obtained results of coal current collector inserts define the need to use method for sorting the coal current collector inserts and the use of a special scheme for equipping pantograph slide. It will allow optimizing their work, knowing the limitations for edges in exploitation and the type of the objective function that should be achieved. The proposed measures can reduce the intensity of the electrical and mechanical wear of materials friction pair «contact wire – current collector inserts». The use of specialized research facility for the study of the friction pair, will allow carrying out the studies to determine the intensity of wear of contact surfaces of the pair of friction and the coefficient of friction at various external factors.

Coal flotation using wash oil as a new type of collector

The use of wash oil as a coal collector is proposed to overcome the disadvantages of regular collectors in coal slime flotation. These disadvantages include high price, limited sources and high consumption. The effect of additives on flotation was studied and an innovative “one rough separation—one cleaning separation” flotation technology was developed. The experimental results show that the clean coal ash content decreases by about 1.36% and the clean coal yield declines by around 10% with the application of the depressant. There is an increase of 3.76% in the yield of clean coal and a decrease of 0.40% in the ash content caused by utilizing a dispersant. An ultimate product having an ash content of 10.78% and yield of 70.12% can be attained using a combination of dispersant and depressant. The use of this new technology decreases the ash content by 1.21%, decreases the yield by 2.80% and an increases the coal flotation perfect index by 2.03%. Compared to common flotation, the utilization of the new technology reduces ash by 0.17%, increases yield by 5.3% and increases perfect index by 4.18%.

Chemical Reagents for Enhanced Coal Flotation

Designing new reagents is of vital importance for the flotation of coal, especially for processing low-rank and/or oxidized coals, which are difficult to float with commonly used fuel oil or kerosene because of the high surface oxygen content. Because of the complex nature of coal surfaces, both hydrogen bonding and aromatic-aromatic interactions were considered in searching for more effective coal collectors. The flotation of two high-sulfur coals was studied in detail, using a series of nonionic surfactants as collectors containing oxygenated as well as aromatic functional groups. Most of the work was conducted with tetra-hydrofurfuryl esters (THF) as the coal collectors, and the performance of these reagents was compared with that of two oily collectors, namely dodecane and nonylbenzene. With some of the reagents, comparable combustible matter recovery can be achieved at a fraction of the dosage of dodecane collector required. More important was the performance of these compounds as promoters for oxidized coal flotation. Finally, joint collector flotation experiments were conducted, and the results showed that a very small addition of a THF reagent before the dodecane addition greatly enhances the flotation of coal. Mechanisms of interaction of these compounds with coal are suggested.

The Influence of Reagent Dosage on the Floatability of Pyrite During Coal Flotation

Abstract In general, as the quantity of frother and/or coal collector is increased, so too, does the flotation of the undesired pyrite. The problem is particularly serious with oily reagents. For some coals, however, a collector, such as fuel oil, is required to achieve a high coal recovery. This requires a compromise between the competing desires of a high coal recovery and a high pyrite rejection. This study gives the quantitative effect of reagent dosage on coal and pyrite floatability and details several means of minimizing pyrite floatability during coal flotation. The effect of fuel oil on coal flotation is especially interesting in that the flotation process changes from froth flotation to emulsion or agglomerative flotation as the amount of oil is increased. This phenomenon provides an additional method of rejecting pyritic sulfur.

炭鉱の珪肺および珪肺結核の結果

Course of illness of 909 miners with silicosis and 143 silicotic miners covered by the Workmen's Compensation Law was observed from 1952 to 1959, 5 to 6 years for each patient. The results are as follows. If silicosis is graded as S0, S1, S2, S3 and S4, with increasing severity, S0-1, are found among workers in employment over 3 years below ground, S1 and the above are among those in employment over 5 years underground, and most silicotic miners covered by the Law are found among those in employment of 7 to 9 years underground. According to the film examination, aggravated cases are found 7.1% in S0-1, 22.5% in S2, and 88.2% in S3. Among these aggravated cases infiltration images are found in 97.6%. Socalled unusually large which has big significance in the aggravation of silicosis is found in 21.1% of S1, 73.5% of S2. The development of this nodulation shows almost no difference among workers of different kinds of work, except significutly low incidencer among coal collectors. However, aggravated cases are found among workers in decreasing degree in such order as: coal-face workers, indirect workers, and collectors. Cases of direct workers, infiltration are mostly of tuberculosis nature, and some of them are due to conglomeration of silicotic modules.