Rainfall-triggered waste dump instability analysis based on surface 3D deformation in physical model test

Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability.

Innuendoes of Sterilisation Drilling in Surface Mining Operations—A Case Study

Surface mining operations play a crucial role in meeting the world’s increasing demand for mineral resources for the advancement of technology and debauched expansion of economies. The search for and exploitation of these mineral resources are therefore important for the sustainability of the mineral extraction industry. To this end, efficient mine planning must incorporate sterilisation drilling and effective waste rock management principles in the search and exploitation of these minerals. In this article, sterilisation drilling is being reviewed vis-a-vis the establishment of waste and tailings dump locations, backfilling of open pit excavations and mine closure giving critical attention to the minerals and mining laws of Ghana. Subsequently, a detailed case study of a surface mining operation that successfully incorporated sterilisation drilling in determining waste dump location in its mine planning process has been presented in this study. The findings indicate that the proposed waste dump location could present a potential mining prospect in the future based on enhanced milling capacity/technology and improved mineral commodity price;underscoring the significance of sterilization drilling in the sustainability of the mining industry.

Triggering mechanism and dynamic process of water-rock flow in Nanfen waste dump in 2010

Water-rock flow is a kind of debris flow with more coarse particles and low viscosity, which occurs in many areas of the world. In this work, the water-rock flow that occurred on May 24, 2010, at Nanfen’s open-pit mine of China was investigated by combining field investigation, meteorological and hydrological survey with numerical simulation to understand its triggering mechanism and dynamic process. The field data shows that the short-term high-intensity rainfall is the most direct inducement to trigger water-rock flow in the waste dump. The loose shallow gravel soil and the V-shaped valley with a certain slope provide the necessary conditions of the occurrence of water-rock flow in the waste dump. Moreover, the possibility criterion of water-rock flow is presented by analyzing the historical rainfall data. In addition, the smoothed particle hydrodynamics(SPH) method was employed to simulate the waterrock flow under the conditions of Newtonian fluid with uniform distribution of water and coarse-grained materials. The simulating results show that the flow distance, velocity, shape, and deposition profile of water-rock flow are in good agreement with the field observation. The present work is beneficial to the risk assessment and mitigation design of water-rock flow disaster in the waste dump.

Classification of fires in coal waste dumps based on Landsat,Aster thermal bands and thermal camera in Polish and Ukrainian mining regions

A self-heating intensity index(SHII)based on the highest(pixel max.)and lowest(pixel min.)values taken from satellite thermal maps of burning coal waste dumps are proposed.The index enables the classification of such fires in Ukrainian-and Polish coal waste dumps.Both in Ukraine and in Poland,varying thermal intensities during 1985–2019 are revealed,using the SHII and following thermal intensity threshold values,namely,extreme thermal activity([7),advanced(3–7),moderate(3–1.5),initial(1.5–1),no activity(<1).The SHII shows decreasing thermal activity in the selected Ukrainian coal waste dumps during 2017–2019.It aids in reconstructing the thermal history of the dumps.Analysis of satellite images revealed a large number of burning coal waste dumps in the Donetsk Coal Basin(Ukraine)with high thermal activity.Such burning likely reflects large amounts of organic matter and sulphides in the dumped material subjected to self-heating and self-burning processes,lack of compaction of the coal waste and/or high methane contents.Comparison of SHII values calculated from satellite-and drone thermal-camera images were compared to show that SHII from drone thermal images have much higher values than those from satellite images;the former have better resolution.Thus,SHII from Landsat-and drone images should be used separately in dump heating studies.

Charging for the waste dumping of open-pit metal mines

Based on the externality theory and the environmental value theory, the hypothesis of charging for waste dumping of open-pit metal mines was put forth. The charging methods were designed according to the characteristics of waste dumping of openpit metal mines, including charging based on the dumping amount of the total waste, multi-charging factors, exceeding standard punishment charging, and so on. The main charging parameter is based on the dumping area rather than the total amount of waste dumping. The charging model of waste dumping of open-pit mines was formulated, and the charging rate was divided into two parts, i.e., the standard charging rate and the differential charging rate. The standard charging rate was derived using the equilibrium dynamic model, whereas the differential one was obtained by establishing the fuzzy synthesized evaluation model.

Occurrence,leaching,and mobility of major and trace elements in a coal mining waste dump:The case of Douro Coalfield,Portugal

The coal mining residues from past mining activities in the Douro Coalfield are emplaced in many dumps near the mining areas,causing substantial environmental impacts.This study aims to contribute to the investigation of environmental impacts caused by the disposal of the residue in the Douro Coalfield through the determination of the geochemical composition of waste materials collected at 3 e 15 m depth,and of the water-leachable fraction produced by percolation in these materials inside the dump.The elements with higher concentration in the leachates are Ca,Cd,Co,Mg,Mn,Na,Ni,S,and Zn,indicating that they are the most easily leached and accessible elements for percolation and mobilization into the environment.The presence of these elements in the leachates is principally attributed to their occurrence as water-soluble ions in clays and sulphides affected by natural weathering conditions,which promotes their breakdown and occurrence as exchangeable ions.The leachates are classified as acid high-metal.Natural weathering and leaching in the Sao Pedro da Cova waste dump are the principal~paths for chemical elements to be percolated and mobilized to environment,posing risk to the soils,waters and ecosystems in the surrounding areas.

Legacy Gold Mine Sites & Dumps in the Witwatersrand: Challenges and Required Action

Legacy mine shafts and waste dumps in the Witwatersrand continue to create social and environmental challenges for communities, even in areas where gold mining ceased over 100 years ago. The slow pace of eradication of these gold mine shafts and waste dumps (or lack thereof) results in conflict between the communities and authorities, particularly the Department of Mineral Resources and Energy (DMRE) as the relevant authority in the field of environmental management in mining. This paper examines, through a literature review, the past and present legislative framework that resulted in legacy mine shafts and dumps and how communities find themselves living next to these mine sites, which results in social and environmental problems. The paper further explores the governments, particularly the DMRE, proposed initiatives to empower those who intend to extract value from the abandoned mines while curbing the scourge of crime in affected communities.

Comparison of Soil Samples from Selected Anthropogenic Sites within Enugu Metropolis for Physicochemical Parameters and Heavy Metal Levels Determination

This study compared the physicochemical parameters and heavy metal levels in soil samples from selected anthropogenic sites within Enugu metropolis, Enugu State, Nigeria using standard analytical methods. Soil samples at depths (0 - 20 cm) and (20 - 40 cm) were collected from waste dump sites, metal scrap dumps, fuel filling stations and auto-mechanic workshops and analyzed for physicochemical characteristics and heavy metal levels. Atomic absorption spectrophotometer was used for heavy metal determination while conventional analytical methods were employed for physicochemical parameters evaluation of the soil samples. At soil depths 0 - 20 cm and 20 - 40 cm the respective mean range of pH, electrical conductivity, organic matter and organic carbon contents in the soil samples were, 6.33 - 6.74, 101.46 - 123.21 μS/cm, 6.41% - 8.35% and 13.73% - 16.14% for auto-mechanic workshops;6.92 - 7.43, 56.46 - 60.02 μS/cm, 1.53% - 2.20% and 11.93% - 12.60% for fuel filling stations;7.14 - 7.84, 70.81 - 77.71 μS/cm, 3.81% - 4.12% and 8.57% - 9.24% for metal scrap dumps;6.54 - 6.81, 94.40 - 100.71 μS/cm, 8.83% - 10.75% and 18.26% - 20.81% for waste dump sites. The pH of the top soil samples from auto-mechanical workshop was below the WHO recommended limits for agricultural purposes. The physic-chemical characteristics of the soil samples decreased with soil depths indicating therefore that anthropogenic activities greatly influence the soil characteristics at the top soils than the sub-soils. The electrical conductivity values of top and sub-soil samples from the studied auto-mechanical workshops were above the recommended limits. At soil depths 0 - 20 cm and 20 - 40 cm, the respective mean range of Zn, Pb and Cd in the soil samples were 17.29 - 19.16 μg/g, 0.704 - 0.96 μg/g and 0.26 - 0.33 μg/g for auto-mechanic workshops;4.13 - 4.88 μg/g, 0.21 - 0.32 μg/g and 0.03 - 0.11 μg/g for fuel filling stations;30.02 - 36.11 μg/g, 0.43 - 0.48 μg/g and 0.15 - 0.19 μg/g for metal scrap dumps;9.30 - 10.84 μg/g, 0.53 - 0.60 μg/g and 0.38 - 0.45 μg/g for waste dump sites. The mean levels of Pb in soil samples from mechanic workshops and waste dump sites were above the recommended permissible limits for agricultural purposes. The study therefore indicated that these sites (auto-mechanic workshops and waste dump sites) could be major sources of Pb pollution to nearby farmlands, streams and the general environment. Plants grown on or around these sites may not produce high yields and could be severely contaminated with heavy metals which portend health danger to food consumers within the environment.