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Characteristics of rhizobacteria in potential hyperaccumulator vegetation and their resistance to gold mine tailing stress

Aminatun Tien, Rakhmawati Anna, Atun Sri, Idrus Arifudin, Simbolon Doly Risdo, Restele Laode

Journal of Water and Land Development

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2024

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no. 60

209--218

EN

The use of local bacteria is preferred in bioleaching as an environmental-friendly alternative technology in gold mining. In a preliminary study, rhizobacteria were isolated and cultured from three types of hyperaccumulator vegetation from the Ratatotok gold mine, Indonesia, namely Pteris vittata L., Syzygium aromaticum L., and Swietenia mahagoni Jacq. These rhizobacteria still need to be characterised and identified. This study is aimed to cover bacterial phenotypic characterisation, assessment of bacteria resistance to tailing, and identification of bacterial strains the exhibit the highest resistance to tailings. The assessment was carried out across a spectrum of tailing concentrations, selecting the three most robust strains for molecular identification. The process involved genotypic characterisation to determine the species name by analysing the 16S rRNA gene. The results reveal that the phenotypic characteristics of the bacteria isolates vary, but all of them are the indole acetic acid (IAA) hormone producers. The highest IAA producer is the isolate from the rhizosphere of S. aromaticum. Based on the genotypic characterisation test, three most resistant isolates to tailing stress are the following strains Pseudomonas aeruginosa (RTKP1) and Stenotrophomonas geniculata (RTKP2), both from the rhizosphere of P. vittata; as well as Bacillus cereus (RTKS) from the rhizosphere of S. aromaticum. These three strains need to be further tested for their bioleaching capability to recover gold from tailings. Additionally, this study recommends that gold recovery using biological agents can combine the role of hyperaccumulator plants in phytomining and rhizobacteria in bioleaching.

2

Geochemistry of the Heavy Metals in the Tansrift Mine (Atlas of Beni Mellal, Morocco) – A Pollution Assessment

Ouahzizi Youssef, Charroud Mohamed, Ali Abdelkhiar Ait, Choukrad Jaouad, El Azzab Driss

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 3

253--263

EN

The Tansrift mine is an open-pit exploitation mine that mines copper substances. It is located on the southwestern flank of the Beni Mellal Atlas, 9 km Northeast of Ouaouizaght village. The mining activity delivered about 650 000 t of 1.5% Cu, with an estimated reserve of 1 Mt to 1.32% Cu. In this study, seven hazardous heavy metals (Cd, Cr, Cu, Pb, Zn, Fe, and Ni) have been studied in the tailing and exploitation of the Tansrift mining district. The geochemical analysis contents of the metals were measured in the samples collected from this area. In addition, the pollution indexes, including the geo-accumulation index, the enrichment factor, the contamination factor, and the pollution load index, were used to assess pollution levels caused by those heavy metals. The Igeo index revealed a high to extreme copper contamination with a value above 4. As for the contamination factor, extreme and moderate contamination is shown by the copper and chrome in the totality of the exploitation and tailing areas. Moreover, the pollution load index shows very high pollution in all samples. The climatic conditions are also affecting the pollution of the atmosphere by contaminated dust and the water table and watershed by the contamination from the tailings and mineralized structures.

3

Estimation of grade and recovery in the concentration of barite tailings by the flotation using the MLR and ANN analyses

Deniz Vedat, Umucu Yakup, Deniz Orcun T.

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 5

art. no. 150646

EN

This study aimed to find optimal models in a comparative framework to estimate the recovery and grade of barite concentrate obtained from the rougher flotation of the barite tailings. Therefore, firstly, the effect of four operating parameters (flotation time, pH, collector dosage, and depressant dosage) on the rougher flotation of the barite tailings containing 37.23% BaSO4 was experimentally investigated. Secondly, two models called the multivariable linear regression (MLR) and the artificial neural network (ANN) were used for the estimation of the recovery and grade of the barite concentrate for the rougher flotation optimization. The R2 values found from the MLR and ANN models were 0.828 and 0.995 for the concentrate recovery, and 0.977 and 0.960 for the barite concentrate grade, respectively. In the comparison of the models determined, it was found that the ANN model expressed quite well than the MLR models, especially for the recovery of the rougher concentrate.

4

Efficiency of Vegetative Reclamation of Coal Spoil Heaps

Popovych Vasyl, Petlovanyi Mykhailo, Henyk Yaroslav, Popovych Nataliya, Bosak Pavlo

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 1

172--177

EN

Coal spoil-heaps cause man-made pressure on the environment of the coal mining area. Coal mining, and in recent years the mass closure of mines, have been accompanied by a negative impact on natural objects and engineering structures; the basements of houses and buildings are flooded, walls and wooden fences rot, crops, trees and bushes are destroyed. Reclamation is carried out on spoil-heaps of coal mines to reduce the man-made pressure. However, in the process of rock dumping on the spoil-heaps, a neorelief begins to emerge causing the vegetation development. The emergence of vegetation groups is a positive phenomenon, as phytomass decomposition promotes the formation of humus. The development of vegetation on the surface of coal spoil-heaps is called vegetative reclamation or phytomelioration. The efficiency of vegetative reclamation is calculated in points and is an indicator of the suitability of a particular man-made object for natural overgrowth. The aim of the work was to establish the features of spatial arrangement of plants in populations on the surface of coal spoil-heaps. It was established that on the coal spoil-heaps, as well as under natural conditions, vegetation tends to aggregate, thus forming phytogenic fields. It should be noted that at different stages of successions, phytogenic fields are formed in different ways. A monocentric phytogenic field arises on the waste heaps during the syngenetic stage of succession. The initial endecogenetic stage of succession provides the formation of phytogenic fields of two types. The first type is the initial polycentric phytogenic field. It is characterized by the ability to combine several individuals of the same species. The second type is a mature polycentric phytogenic field. It is characterized by higher resistance, and plant community is already able to convert geoprocesses. The mature endoecogenic stage of succession is characterized by the development and expansion of tree species, and the phytogenic field is acentric and global. This kind of phytogenic fields is found on tailings with artificial vegetative reclamation.

5

Application of multiple linear regression (MLR) analysis for concentration of chromite tailings by the flotation

Deniz Vedat

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 4

579--589

EN

In this study, the concentration of chromite minerals by amine flotation of a chromite tailing (slime) with content 23.84% Cr2O3 from Yeşilova-Burdur (Turkey) was investigated. In experimental studies, firstly, some operating parameters of the rougher flotation observed for a low-grade chromite tailing were investigated. Secondly, multiple linear regression (MLR) analyses were performed to determine the effects of some operating parameters on the performance of the rougher amine flotation. From the experimental results, multiple linear regression equations were developed to predict the recovery and grade of the chromite concentrate, and the regression coefficients between experimental and predicted values were found to be quite good (R2 values of 0.772 and 0.917, respectively). Additionally, it was found that the conditioning time and low pH value using H2SO4 showed an important effect on the recovery and the grade of the chromite concentrate.

6

Speciation of Mercury Contaminant in Public Gold Mine Tailing and its Stabilization Using Sulfur and Sulfide

Trihadiningrum Yulinah, Latif Rezki Amalia, Rachman Ranno Marlany

Journal of Ecological Engineering

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2019

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Vol. 20, nr 4

29--34

EN

The mercury-containing tailing waste from public gold mines in Indonesia is generally deposited on soil without treatment. This research aimed at determining the amount and composition of mercury species in the tailing, and testing the effect of sulfur and sulfide on mercury stabilization. Samples were collected from a tailing pile at different depths in a public gold mine in Kulon Progo, Indonesia. The samples were characterized according to the mercury concentrations and Toxicity Characteristic Leaching Procedure (TCLP) test. Mercury speciation was carried out using nitrogen gas flow into tailing samples, which were placed in three test tubes. The released mercuric species was entrapped in KCl and KmnO4 solutions. The mercury stabilization was carried out using sulfur and sodium sulfide. TCLP test was performed to the stabilization products. The mercury concentrations were measured using a mercury analyzer. The results showed that the mercury in the tailings were dominated by elemental Hgo, the concentrations of which in the tailing piles of 30, 60, and 90 cm depths were 74.7%, 71.6%, and 76.5% respectively. Those of ionic Hg2+ form were 25.3%, 28.4%, and 23.5%, respectively. Additions of sulfur powder and sodium sulfide solution produced stable black-colored mercury sulfide. When compared to sulfide, sulfur was more recommended for stabilizing mercury in the tailing waste.

7

An investigation of the effect of NaCl concentration on the electrocoagulation of coal preparation plant tailings

Eskibalci M. F., Ozkan M. F.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

934--943

EN

Coal preparation is the process of separating the coal from mineral impurities to produce high-grade coal, and the wastewater of the coal separation process is mainly consisted of fine coal and clay particles. Electrocoagulation (EC) is one of the effective methods for wastewater treatment. In this context, this study was aimed to investigate the evaluation of EC process for coal preparation plant wastewaters. Several key parameters affecting the efficiency of EC were investigated with laboratory scale experiments in search of optimal parameter values. Most importantly, the effect of NaCl concentration on the precipitation of coal preparation plant tailings by EC was investigated. Current density, electrolysis time, mixing speed, mixing time, pH, and salt concentration were studied using an aluminum electrode. Based on the results obtained from this study, the optimum conditions were found to be as pH 7.88 (natural pH), current density 40 (A/m2), mixing speed 360 rpm, premixing time 120 sec, and electrolysis time 300 sec. Under the optimum operating conditions, the results indicated that EC can be successfully applied for the coal preparation wastewaters, and the turbidity was reduced from 1260 NTU to 63 NTU (95% efficiency) with an operating cost of $5.67/Mg of tailings. By the increasing the salt content, a small increase in the turbidity was observed with a decrease in the voltage. With only a 1% decrease in the removal efficiency, the cost was reduced to $3.19/Mg with a 44% operating cost reduction.