Evaluation of copper tailings from the abandoned Messina Mine for possible reuse in recreational projects, South Africa

Historic mining of copper around Musina Town left behind a sizeable unrehabilitated tailing dump. This article reports on the study conducted to investigate the suitability of using copper tailings as sand replacement in recreational projects. The methodology used involved analyzing the particle size distribution and plasticity index (PI) of the tailings and determining their particle density, bulk density, particle shape, total porosity, and permeability coefficient. The pH of the tailings, major element oxides, and heavy metals composition were all analyzed. The tailings were classified as poorly graded sand with silt (SP-SM). Low fines (9.6%) and PI (1.4) values revealed that the copper tailings were texturally suitable for application in rootzones of sports fields, courts for beach volleyball, and bunkers of the golf courses. Their particle density (2.90 g/cm³), bulk density (1.53-1.89 g/cm³), porosity (34.62-47.04%), and permeability (1.42 x 10-3 cm/sec) were all within the recommended range for application in rootzones. The angular particles of the tailings supported their uses in the bunkers. However, their pH (7.9) and high quartz content (69% SiO2) confirmed their suitability for rootzones. However, the high concentration of Cu (1872.0 mg/kg) and Cr (159.5 mg/kg) was identified as a potential risk of using the copper tailings in rootzones. This and the relatively high Al2O3 (11%) and Fe2O3 (8%) suggested that the copper tailings should be first washed or processed before being used in any recreational projects. Developing a suitable technique for processing the studied copper tailings to enhance their properties for different recreational projects was recommended.

Modeling the Process of Thawing of Tailings Dam Base Soils by Technological Waters

The storage of wastes from mining and mineral processing plants in the tailing dumps in regions with cold climates has a number of environmental consequences. Interactions of water with tailings in cold climates often lead to the thawing of permafrost soils, formation of technogenic thawing zones, and leakage of drainage waters. In the case of fault zones development in these areas, technogenic solutions are often filtered outside the tailing dump, promoting further development of filtration channels. In order to prevent leakage of solution from tailing dumps over time, it is necessary to determine the thawing zones and prevent the formation of filtration channels. In the case of the formation of a filtration channel, it is necessary to know what rate of rock thawing occurred near the formed filtration channel. In this study, for the tailing dump of a diamond mining factory, we calculated two exothermic effects: (1) due to physical heating of dump rock by filtering industrial water with temperatures from 2 to 15 °C through the rock; and (2) due to the chemical interaction of industrial water with the dam base rock. The amount of energy transferred by the water to the frozen and thawed rock over 10 years was calculated using thermophysical modeling and was 207.8 GJ and 8.39 GJ respectively. The amount of energy that the rock received during the ten-year period due to dissolution of the limestones and equilibration of solutions was calculated using thermodynamic modeling and was 0.37 GJ, which is 4.4% of the average amount of energy, expended on heating the thawed rock (8.39 GJ).

Toxic element distribution analysis in tailing technozems of the lead-zinc deposits in Eastern Transbaikalia

An analysis of chemical element distribution in technozems of tailing dumps of the lead-zinc deposits of Eastern Transbaikalia is carried out. The potential toxicity of tailing mine technozems was calculated. A comparative analysis of the toxic element concentrations in the technozems of the lead-zinc deposit tailing dumps has revealed significant differences in the concentrations of toxic elements. It was found that the highest concentrations of toxic elements of the first class of hazard (As, Pb, Zn, and Cd) are characterized by the technozems of the Blagodatsky Deposit, while the lowest concentrations by those of the Khapcheranginsky Deposit. It has been established that the greatest ecological hazard is posed by the tailing dump of the Blagodatsky lead-zinc deposit, whereas a significantly smaller one by tailing dumps of the Khapcheranginsky and Novo-Shirokinsky deposits.

ENSURING THE SAFETY OF THE GIZHGIT RIVER BASIN (BAKSAN GORGE, KABARDINO-BALKARIA)

The article presents materials on the current state of the Tyrnyauz Mining and Processing Plant’s tailing dump, its negative impact on the environment and a possible scenario of this impact in the future. An analysis of the development of dangerous natural processes in this area is given. The author indicates measures that can ensure the safety of this facility, and work currently being done in that direction is noted. The article considers measures for the reclamation of the dry beach of the tailings dump of Tyrnyauz Mining and Processing Plant, including the restoration of the discharge well, in the interest of preventing environmental contamination risks in the Gizhgit river basin area.

Efficiency Assessment of Allflot Pneumatic Flotation Machines in Beneficiation Slime Fraction of Old Tailings at Norilsk Processing Plant

The article presents a rational technology for processing old tailings and slime (cyclone overflows) of the -25+0 microns class at tailing dump No. 1 of the Norilsk Processing Plant. One of the current and urgent problems is the lack of an efficient technology to process the slime part of old tailings with fine particles of useful metals, which is not processed and is transferred to temporary tailing dump. Current development state of the flotation equipment and technologies allows to consider the problem of coarse-size particle flotability generally solved. The results of pilot testing of the Allflot pneumatic flotation cell that operates at the 5% content of solids in the slime at Nordinves LLC are presented. Comparative materials are provided on the Allflot re-treatment slurry flotation cell (500 l) and a laboratory mechanical machine (1.5 l). The results of qualitative and quantitative calculations of the flotation process as applied to the slime fraction of old tailings are given. Conclusions about the economic feasibility of using the Allflot Pneumatic Flotation Machine for slime beneficiation are made.

Investigation of biological activity of recultivated iron ore processing wastes of Abagur agglomeration and processing plant, Novokuznetsk

The problem of biotransformation of man-caused disturbed lands is of great importance for the restoration of soil fertility. The leading role in this process is played by soil microorganisms. Toxic industrial waste can make negative adjustments to the species composition of soil microflora (can cause mutation of many microorganisms, as well as the death of some of them). Under certain conditions, in the presence of harmful substances, new microorganisms can arise that decompose precisely those substances that cause soil pollution. Consequently, a new microflora appears, capable of carrying out its trophic functions on an inductive basis on industrially contaminated substrates. As a man-caused control, a mineral substrate of the tailing dump of Abagurskaya agglomeration and processing plant JSC, unfavorable for the vital activity of soil microflora, where, due to the absence of plant residues and other carbon-containing components, an extremely low level of intensity of enzymatic hydrolytic processes was used. The introduction of organic matter containing sewage sludge (WWS) into the substrate as a recultivator creates favorable conditions for the formation of a stable vegetation cover. The presence of an organic component in the mineral substrate of the iron-containing tailings waste creates favorable conditions for the vital activity of microflora. Carbon-containing compounds of technozems create a certain pool of microorganisms. The products of their vital activity create the basis for the formation of an organic-mineral substrate, favorable conditions for the growth of higher plants and the creation of a stable phytocenosis. For the induced manifestation of enzymatic activity under these extreme conditions, a considerable time is required for the bacterial forms introduced from the outside to be able to fix their presence. The maximum activity, comparable both after 1 month and after 3 months with the natural control, was noted on the experimental site with the placement of WWS as a soil conditioner. The presence of WWS and intensive accumulation of leaf litter and other plant residues contribute to the favorable development of cellulose-degrading bacteria, among which rod-shaped forms of the genus Clostridium predominate. The quantitative indicators of the enzymatic activity of technozems are close to the natural level and significantly exceed those of technogenic control.

MEASUREMENT OF RADON CONCENTRATION IN SOIL SAMPLES OF MAZAT AND KAFI-HABU MINING SITES, PLATEAU, NIGERIA

Radon and its short-lived progenies contributed significantly to natural background radiation. Long-term exposure to such radiation increases the probability of lung cancer to persons. To assess the radiological hazards associated with the inhalation of radon gas from ore dust in Mazat and Kafi-Habu mining sites of Plateau, Nigeria, 12 soil samples from an abandoned tailing dump ground were collected and analysed for radon using RAD-7 electronic detector. The dose rate of each sampling point was directly measured using RADOS RDS -120 portable survey meter. The results gave a mean radon concentration ranging from 771.51 ± 21.9 Bq/m3 to 5666.13 ± 28.8 Bq/m3 with 3451.13 ± 42.9 Bq/m3as the average value for all measurements. The average concentration of measurements from Mazat and Kafi-Habu is 3671.6 ± 41.2 Bq/m3 and 3010.16 ± 46.5 Bq/m3 respectively. The average values obtained from the analysis are significantly higher than the upper limit of 300 Bq/m3 set by the International Commission on Radiological Protection (ICRP) suggesting quick remediation on the host communities. The geometrical mean value of Dose Rate (DR) and Annual Effective Dose Equivalent (AEDE) were 870 nGy/hr and 1.04 mSv/yr respectively. Again, these values are above the global average limits of 59 nGy/hr and 1 mSv/yr. The result indicates that miners working in those sites and dwellers of the study areas are at higher risk of getting exposed to radon and need to employ protective measures. This work is useful in monitoring and control of radon level for the on-site workers and the

MODELIND OF THE PROCESS OF DISSOLUTION OF SOILS IN THE BASE OF A HYDRAULIC STRUCTURE BY ATMOSPHERIC WATER

The article presents the results of a flow-through experiment simulating the process of dissolution of soils of the foundation of a dam of a hydraulic structure by groundwater. The object of the study is the tailing dump of the concentrating plant, during the operation of which the permafrost soils of the coastal abutments of the enclosing dam thawed, significant volumes of circulating water leaked into the shunting tank located below. The development of filtration channels in fractured tectonic zones that make up the near-rock massif does not stop. Upon completion of the experiment, which lasted 20 weeks, an array of measured parameters of solutions at the exit from the columns was obtained: pH, specific conductivity and elemental composition. The data obtained made it possible to estimate the rate of dissolution of the soils of the dam foundation.