Wyniki wyszukiwania - Biblioteka Nauki

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Application of low-field NMR in the study of flocculant-aided filtration process of coal tailings

100%

Guo Z. , Liang L. , Hu P.

Physicochemical Problems of Mineral Processing

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2021

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tom Vol. 57, iss. 3

1--7

EN

Preconditioning of coal tailings with flocculants is a useful technology to improve filtration performance. In this study, anionic and cationic polyacrylamides were used for the pretreatment coal tailings before filtration. Nondestructive and rapid measurement of the filter cakes of coal tailings at different filtration stages was conducted using a nuclear magnetic resonance (NMR). The transverse relaxation time (T2) results of NMR provided the information concerned the state of water in filter cake, showing that free water entrapped in larger pores was removed mainly during coal tailings filtration, and the pressure in this study cannot remove the inherent moisture of filter cake of coal tailings. The significant increase in the amplitude of T2 value between 0.1 and 1.0 ms revealed that the flocs collapsed into smaller ones with water entrapped in them during filtration. Comparing the NMR results with different flocculants shows that anionic polyacrylamide of 800 g/Mg produced a larger structure in the initial stage of filter cake formation. The final filter cake entrapped more water. The NMR results well validated the filtration experiments.

2

Effect of shear-induced breakage and reflocculation on the floc structure, settling, and dewatering of coal tailings

100%

Fan Y. , Ma X. , Song S. , Dong X. , Chen R. , Dong Y.

Physicochemical Problems of Mineral Processing

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2020

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tom Vol. 56, iss. 2

363--373

EN

Flocculation is crucial for the treatment of coal tailings in industries. In this paper, the effects of shear-induced breakage and reflocculation of the floc, settling, and dewatering of coal tailings were investigated. The results show that as shear strength increases, the settling velocity of flocculated tailings decreases. A shear rate of 200 rpm (170.6 s-1) leads to the loss of half the settling velocity. However, at high dosage cases, 200 rpm-300 rpm shear could improve the clarity of the supernatant. Small particles are flocculated preferentially, especially for particles below 10 µm. With the increase in dosage, the critical particle size for the occurrence of flocculation increases. The chaos index proposed can quantitatively reflect the degree of flocculation or reflocculation of coal tailings. At high dosage conditions, shear could enhance the dewatering performance of flocs by reconstructing the filter cake. Controlling the structure of flocs by dosage and shear strength can help obtain appropriate settling, clarifying, and dewatering performance of coal tailings.

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Investigation of flocculation properties and floc structure of coal processing plant tailings in the presence of monovalent and divalent ions

86%

Gungoren C. , Unver I. K. , Ozdemir O.

Physicochemical Problems of Mineral Processing

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2020

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tom Vol. 56, iss. 5

747--758

EN

Low-rank coals are generally processed with wet methods including washing, flotation, etc. Fine-sized tailings of these processes are discharged to tailing ponds with a significant amount of associated water which contains a high amount of dissolved ions. These tailings should be dewatered employing coagulation/flocculation in terms of technological and environmental aspects. In this study, the coagulation/flocculation behavior of coal processing plant tailings obtained from Manisa, Turkey was investigated in the presence of monovalent (Na+, K+) and divalent (Mg2+, Ca2+) ions and an anionic flocculant (SPP-600). First, the coagulation properties of coal tailings were determined. Then, the flocculation experiments were carried out, and the turbidity values of the suspensions were measured. Moreover, the sizes of the flocs were determined using a laser diffraction particle size analyzer to analyze the strength of the flocs. The results of the coagulation experiments showed that while divalent ions were more effective at 10-1 mol/dm3, higher settling rate and lower turbidity values were obtained in the presence of monovalent ions at 1 mol/dm3 concentration. The optimum flocculant dosage was obtained as 150 g/Mg from the flocculation experiments. The floc size and strength measurements indicated that the larger flocs were obtained with Na+ than Ca2+ in the presence of the flocculant. The strongest flocs were obtained at 10-1 mol/dm3 Ca2+ + 150 g/Mg flocculant. It can be concluded from this study that the coagulation followed by the flocculation method can be employed to obtain fast flocculation behavior and low turbidity for the dewatering of coal tailings.

4

Separation of Materials Containing Rare Earth Elements using Screening and Magnetic Separation

72%

Baron R. , Friebe P. , Matusiak P. , Kowol D. , Suponik T. , Lutyński M.

Inżynieria Mineralna

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2024

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tom Vol. 2, no. 1

227--234

EN

This article presents research on selected materials with the aim of determining their rare earth element (REE) content and attempting to intensify it. The test material was coal slurry, which is a waste product from the operation of a preparation plant of a closed coal mine. Research on REE concentration intensification tests was carried out using magnetic separation. Laboratory analyses determining the REE content in the samples obtained, were carried out using the inductively coupled plasma ionisation mass spectrometry (ICP-MS) technique. Carrying out this research by the KOMAG Institute of Mining Technology, is a continuation of work related to making mining waste economically useful and determining a new source of REE recovery. Previous research and development work showed REE content (scandium 40.49 ppm) in the coal slurries studied. The result of the work carried out is the determination of the economic utility of REE recovery from the studied waste.

PL

W artykule przedstawiono badania wybranych materiałów mające na celu określenie zawartości pierwiastków ziem rzadkich (REE) oraz próbę ich wzbogacania. Materiałem badawczym była zawiesina węglowa, która jest produktem odpadowym z eksploatacji zakładu przeróbczego zamkniętej kopalni węgla kamiennego. Badania nad testami wzbogacania REE przeprowadzono z wykorzystaniem separacji magnetycznej. Analizy laboratoryjne określające zawartość REE w pobranych próbkach przeprowadzono z wykorzystaniem techniki spektrometrii mas z jonizacją plazmą wzbudzoną indukcyjnie (ICP-MS). Przeprowadzenie tych badań przez Instytut Techniki Górniczej KOMAG jest kontynuacją prac związanych z ekonomiczną przydatnością odpadów górniczych oraz określeniem nowego źródła odzysku REE. Poprzednie prace badawczo-rozwojowe wykazały zawartość REE (skand 40,49 ppm) w badanych zawiesinach węglowych. Wynikiem przeprowadzonych prac jest określenie ekonomicznej użyteczności odzysku REE z badanych odpadów.