SITE WIDE WATER BALANCE OF THE EAST BOULDER MINE

Water management within the Mining Industry is an important issue. Operating a mine is a water intensive process and in order to meet the goals of mining operations, water resources must be tracked and monitored, not only to comply with state and federal regulations, but also to optimize the mining operations. Sibanye-Stillwater (formerly known as Stillwater Mining Company) operates two underground mines, the Stillwater Mine and the East Boulder Mine, both located in the Beartooth Mountain Range of South Central Montana. The East Boulder Mine targets platinum group metals found within the J-M Reef geological formation. This thesis focuses on developing an operational, site wide water balance for the Easter Boulder Mine under base flow conditions as well as different proposed flow scenarios. Flow data from 2015 was provided by Sibanye-Stillwater to quantify the water balance and model the proposed flow scenarios. Since the mine is operational, historical data can be used to quantify many of the uncertainties associated with creating a water balance, therefore minimizing the need of probabilistic software and allowing for the use of Microsoft Excel to be used to create the water balance. Different flow scenarios were proposed with the intention to improve water treatment plant operating efficiencies. An onsite water treatment plant is used to remove contaminants in the water caused by the underground mining operations. Nitrate, a byproduct of the underground blasting agent, is the main contaminate of concern for the East Boulder Mine. The proposed flow scenarios focused on the effects of changing the flow direction of the mine adit water within the system. The results of the water balance indicate that it is possible to improve water treatment plant operating efficiencies by changing the onsite mine water flow direction. This research also identified the need for additional onsite flow monitoring and improvements made to the flow monitoring database. The results of this research can be used to make informed decisions in regards to mine operation and water resource management. The results of this thesis show that a water balance can be performed on an operational mine site and highlight possible improvements that can be made to water flow paths that may result in improved operational performance

Performance Comparison between Neutralization Tailings and Flotation Tailings Used for Backfill Mix and Mechanism Analysis

A comparison test of different tailings used for underground backfill was conducted, using neutralized tailings from BIOX and flotation tailings of Jinfeng Mine. Laboratory comparison test results show that, with neutralized tailings, when the cement dosage is at 19%, backfill UCS after 7 days, 14 days, and 28 days are 105%–163%, 80%–102%, and 33%–43%, respectively, which are higher than those of flotation tailings. When the cement dosage is at 12%, backfill UCS after 7 days, 14 days, and 28 days are 58%–77%, 50%–60%, and 28%–51%, respectively, which are higher than those of flotation tailings. Slurry fluidity of neutralized tailings is lower than that of flotation tailings, while, in these two tailings, the difference of slump and diffusivity values is less than 6%, which is not a significant difference in slurry fluidity. The reason for neutralized tailings showing higher UCS is as follows: during backfill curing, neutralization tailings produce abundant crystals of CaSO4·2H2O in interlaced structure which helps in combining aggregates closely; CaSO4·2H2O hydrates with C3A C4AF contained in the cement and forms clavate cement bacillus which works as a micro reinforcing steel bar. The test proved that neutralized tailings are more optimal for backfilling

Analytical and Experimental Evaluation of the Settlement and Volume Variation of Tailings Slurry Deposited in Containment Structures

Résumé Les résidus miniers sont des rejets de moulins de concentrateur, qui sont généralement déposés dans des parcs à résidus miniers en surface. En cas d’une gestion inappropriée, les résidus miniers peuvent entraîner des catastrophes à l’environnement et aux vies. L’utilisation des résidus miniers comme un matériau de remblai pour remplir les chantiers miniers souterrains permet de réduire la quantité des résidus miniers déposés en surface. En plus, le remblayage des chantiers souterrains permet d’améliorer la stabilité du terrain et augmenter la récupération du minerai. Lorsque les résidus miniers sont déposés dans les parcs à résidus miniers, leur volume peut diminuer en raison de la sédimentation, de la consolidation sous poids propre et du retrait par évaporation. Une estimation appropriée de la variation du volume des résidus miniers est nécessaire pour éviter le dépassement de la capacité de stockage conçue des parcs à résidus miniers. Les trois processus (la sédimentation, la consolidation sous poids propre et le retrait par évaporation) peuvent avoir lieu également au remblai en pulpe lors de sa déposition dans un chantier souterrain. La variation du volume de remblai doit être évaluée correctement pour assurer la stabilité des barricades et un contact serré entre le remblai et les toits des chantiers ou pour éviter de créer des espaces vides importants entre la surface du remblai et le plancher de galerie de niveau supérieur. Le principal objectif de ce mémoire est d'évaluer l'affaissement et la variation de volume des résidus miniers dans les parcs à résidus miniers ou des remblais en pulpes dans les chantiers souterrains. Afin d'atteindre l’objectif principal, une compréhension approfondie de la variation du volume des résidus miniers ou des remblais en pulpe associée aux processus de la sédimentation, de la consolidation et du retrait par évaporation est nécessaire. La recherche bibliographique montre que pratiquement tous les travaux de recherche ont porté sur les études de la consolidation des résidus miniers ou des remblais en pulpe. Il y a peu de travaux portant sur la sédimentation. L’indice des vides à la transition entre la sédimentation et la consolidation est un paramètre critique, mais sa détermination reste encore inconnue. Dans ce mémoire, on a montré que la phase de retrait normal d’une courbe de retrait par évaporation est très similaire au processus de sédimentation. Ainsi, l’indice des vides au début de désaturation (correspondant à la valeur d’entrée d’air) eAEV sur la courbe de retrait est considéré comme identique à l’indice des vides critique à la fin de sédimentation ou au début de consolidation. Suite à ces analyses, deux solutions analytiques ont été proposées en considérant la variation de volume des résidus miniers ou des remblais en pulpe associée aux processus de la sédimentation, de la consolidation et du retrait par évaporation. La première a été développée en considérant l’indice des vides final ef d’une courbe de retrait afin d’estimer l’affaissement ou la variation du volume des résidus miniers dans des parcs à résidus miniers dans des régions arides ou semi-arides. La deuxième a été formulée en utilisant l’indice des vides au début de désaturation eAEV et le coefficient de compression obtenu par un essai de consolidation standard pour évaluer l’affaissement ou la variation de volume des remblais en pulpe dans des chantiers souterrains ou des résidus miniers dans des parcs à résidus miniers dans des régions non-arides. Les deux solutions analytiques proposées ont été validées avec succès par des résultats expérimentaux obtenus par des essais au laboratoire en modèle physique. Les solutions proposées peuvent être utilisées pour calculer l’affaissement et la variation du volume des résidus miniers ou des remblais en pulpe, au moins dans la phrase préliminaire d’un projet. L’application des solutions proposées pour évaluer l’affaissement ou la variation du volume des résidus miniers ou des remblais en pulpe nécessite de faire des essais de retrait par évaporation. Ce type d’essais est facile à réaliser et assez courant en mécanique des sols. On voit également quelques travaux d’essais au laboratoire pour obtenir les courbes de retrait des résidus miniers non cimentés. Pour le remblayage des chantiers souterrains, les remblais sont souvent cimentés. Ceci est particulièrement vrai pour les remblais en pâte. Or, la revue de littérature montre qu’il n’existe pas de travaux portant sur les essais de retrait par évaporation des remblais en pâtes cimentés. Pour combler cette lacune, une série d’essais de retrait par évaporation a été menée pour acquérir les courbes de retrait d’un remblai en pâte cimenté et non cimenté en considérant différentes teneurs en ciment et teneurs en eau initiales. Leur influence sur les paramètres de retrait, incluant l’indice des vides final ef, la limite de retrait ws, l’indice des vides (eAEV) et la teneur en eau (wAEV) au début de désaturation a également été étudiée. Les résultats indiquent que les valeurs de ces paramètres de retrait des remblais cimentés sont beaucoup plus élevées que celles des remblais non cimentés pour une teneur en eau initiale donnée. L'augmentation de la teneur en ciment de 3 à 7% entraîne une légère augmentation des valeurs de ces paramètres de retrait. Pour une teneur en ciment donnée, les valeurs des paramètres de retrait peuvent varier significativement avec la variation de la teneur en eau initiale. Les principaux résultats ont été présentés dans deux articles de revues soumis. Des résultats supplémentaires sur les essais de retrait par évaporation et sur les essais de consolidation sont présentés dans les annexes. ----------Abstract Tailings are mine wastes produced by milling process, which are conventionally deposited on ground surface in tailings storage facility (TSF). In case of inappropriate management, the surface disposal of tailings can lead to undesirable consequences to the environment and lives. In underground mines, the use of tailings as a filling material to fill underground mined stopes allows reduction of surface disposal of tailings. Stope backfilling also helps improve ground stability and increase ore recovery. When slurried tailings are deposited in a TSF, the volume of the tailings tends to diminish due to sedimentation, self-weight consolidation and shrinkage by evaporation. An accurate estimation of the volume change of deposited tailings is necessary to help better optimize the life cycle management. The three processes (sedimentation, self-weight consolidation and shrinkage by evaporation) also take place in backfill slurry, placed in underground mine stopes. The volume variation of the backfill slurry should be correctly evaluated to ensure the stability of barricade and to ensure a tight contact between backfill and stope roof or to avoid excess void space between the top surface of the backfill and the floor of over cut drift. The main objective of the thesis is to estimate the settlement and volume variation of tailings deposited in TSF or of backfill slurry in underground mine stopes. In order to reach the main objective, a comprehensive understanding of the volume change of tailings or backfill slurry associated with the processes of sedimentation, consolidation and shrinkage by evaporation is necessary. A literature review showed that the consolidation of tailings or backfill slurry has been largely investigated while the study on the sedimentation of tailings or backfill slurry is almost absent. The void ratio at the transition between sedimentation and consolidation is a critical parameter. Its determination however remains unknown. In this thesis, one shows that the normal shrinkage stage of shrinkage curve is very similar to the process of sedimentation. Thus, the unsaturation onset (i.e. air entry value) void ratio eAEV on the shrinkage curve can be considered as identical to the critical void ratio at the end of sedimentation or at the beginning of consolidation. Bases on the above analyses, two analytical solutions have been proposed by considering the volume change of tailings or backfill slurry associated with the processes of sedimentation, consolidation and shrinkage by evaporation. The first one was developed by considering the final void ratio ef of shrinkage curve in order to estimate the settlement or volume change of tailings deposited in a TSF in arid or semi-arid regions. The second one was formulated by using the unsaturation onset void ratio eAEV and the coefficient of compression obtained by standard consolidation test to evaluate the settlement or volume variation of backfill slurry placed in underground mine stopes or tailings deposited in a TSF in non arid regions. The two proposed analytical solutions have been successfully verified by experimental results obtained by physical model tests. The proposed solutions can thus be used to estimate the settlement and volume variation of tailings or backfill slurry, at least in the preliminary stage of a project. The application of the proposed solutions for evaluating the settlement or volume variation of tailings or backfill slurry requires to perform shrinkage tests. This type of tests is easy to do and quite common in soil mechanics. One sees a few works published on laboratory tests to obtain shrinkage curves of uncemented tailings. For underground mines, backfills are usually cemented. This is particularly true for paste backfill. The literature review however showed that there is no published work on shrinkage tests of cemented paste backfill. To fill this gap, a series of shrinkage tests has been performed to obtain the shrinkage curves of cemented and uncemented paste backfill by considering different cement contents and initial water contents. Their influence on the shrinkage parameters, including the final void ratio ef, shrinkage limit ws, unsaturation onset void ratio (eAEV) and water content (wAEV) has also been evaluated. The results indicate that the values of shrinkage parameters of cemented backfill are much higher than those of uncemented backfill at a given initial water content. An increase of cement content from 3 to 7% results in a slight increase in the values of shrinkage parameters. For a given cement content, the values of shrinkage parameters can significantly vary with the variation of initial water content. The principal results have been presented in two submitted journal papers. Additional results on shrinkage tests and consolidation tests are presented in the appendices

METODE AHP DALAM PEMILIHAN STRATEGI PADA AKTIFITAS PENAMBANGAN FRONT PRODUKSI PT CSD: PENAMBANGAN FULL FACE DAN TOP HEADING AND BENCHIN

ABSTRAK PT CSD dikategorikan sebagai marginal ore deposit dengan kadar berkisar 6 gpt mengacu pada klasifikasi kadar emas di Indonesia. Oleh karena itu, strategi penambangan menjadi pertimbangan penting untuk mendapatkan nilai yang lebih ekonomis (Purwanto, 2015). Berdasarkan laporan investigasi geoteknik, ratio tekanan in-situ vertikal dan horizontal di Cibaliung adalah 4.8 MPa:9.2 Mpa atau 1:2, yang berarti tekanan horizontal di Cibaliung dua kali lebih besar dibandingkan dengan tekanan vertikalnya (Campi dan Dugan, 2004). Secara sederhana bisa disimpukan bahwa strategi untuk mempercepat aktifitas produksi secara aman lebih baik dilakukan penambahan ketinggian pada bukaan front produksi dari pada memperlebar dimensi bukaan. Dari sudut pandang biaya pengerjaan bukaan front, biaya metode full face lebih murah ketimbang metode top heading and benching. Adapun untuk tingkat keamanan maka berlaku sebaliknya (Bin Zhu dan Xiaojing Shi, 2013). Analisa keekonomisan pada kegiatan penambangan perlu juga mempertimbangkan tonase ore yang terekstrak/perolehan logam Au untuk menentukan skema mana yang paling sesuai. Pemilihan skema penambangan menggunakan metode Analytical Hierarchy Process (AHP) dengan menggunakan tiga kriteria (kestabilan, biaya penambangan, tonase ore) dan empat pilihan skema (full face 1, full face 2, THB 1 dan THB 2). Hasil perhitungan menggunakan metode AHP didapatkan peringkat skema tertinggi sampai terendah: full face 1 (0.343), THB 2 (0.260), THB 1 (0.215), full face 2 (0.182). Kata Kunci: analisa kestabilan, studi keekonomisan, metode AHP, strategi penambangan  ABSTRACT PT CSD is categorized as a marginal ore deposit with ore grade around 6 ppm, based on the classification of gold grade in Indonesia. Therefore, the mining strategy is an important consideration to get a more economical value (Purwanto, 2015). Based on the geotechnical investigation report, the ratio of vertical and horizontal in-situ pressure in Cibaliung is 4.8 MPa: 9.2 Mpa or 1: 2, which means the horizontal pressure in Cibaliung is twice as high as its vertical pressure (Campi and Dugan, 2004). In simple terms it can be concluded that the strategy to accelerate production activities safely is heightening rather than widening the dimension of the production stope. From the point of view of tunnel/stope construction cost, the cost of the full face method is cheaper than the top heading and benching method. As for the security level, the opposite applies (Bin Zhu and Xiaojing Shi, 2013). Economic analysis in mining activities also needs to consider the tonnage of ore extracted / Au produced for deciding which scheme is appropriate. The selection of mining schemes uses the Analytical Hierarchy Process (AHP) method using three criteria (stability, mining costs, ore tonnage) and four scheme options (full face 1, full face 2, THB 1 and THB 2). The results of calculations using the AHP method obtained the highest to lowest scheme ratings: full face 1 (0.343), THB 2 (0.260), THB 1 (0.215), full face 2 (0.182). Key Words: stability analyses, economic study, AHP method, mining stra

Simulation study of the velocity profile and deflection rate of non-Newtonian fluids in the bend part of the pipe

As resource extraction moves deeper underground, backfill mining has received a lot of attention from the industry as a very promising mining method that can provide a safe workplace for workers. However, the safe and efficient transport of fill slurry through pipelines still needs more exploration, especially in the bend section. In order to investigate the flow characteristics and velocity evolution of the slurry in the bend section of the pipe, a three-dimensional (3D) pipe model was developed using the computational fluid dynamics software Fluent, and nine sets of two-factor, three-level simulations were performed. Furthermore, a single-factor analysis was presented to investigate the effects of the two main influencing factors on the shifting of the maximum velocity of the slurry towards the distal side in the bend section, respectively. Then, the response surface analysis method was applied to the two-factor analysis of the maximum velocity shift and the weights of the two influencing factors were specified

Consolidation and Arching Potential of Slurry Backfill

Soil-bentonite (SB) slurry walls are one of the most popular techniques for minimizing the horizontal migration of contaminants. Backfill arching, or “hang-up” of the backfilled slurry, on the wall trench has the potential to significantly reduce the effectiveness of these barriers. This research was conducted to supplement the design and installation of an 11,000 m long slurry wall at PotashCorp’s mine in Rocanville, Saskatchewan. The slurry wall is being installed through low permeability glacial till containing permeable granular zones. This study was undertaken to improve the understanding of vertical stress distribution in these deep barriers. In particular, the objective of this study was to develop an understanding of the factors controlling arching and hydraulic conductivity (k) of SB walls. Slurry wall “hang-up” or arching is dependent on shear along the wall of the trench and on a coefficient of lateral earth pressure (K). Consolidated drained (CD) shear box tests were conducted to study the shear strength parameters of the backfill mixes. Six inch proctor mold was modified with load cells on the side walls to measure horizontal stresses along with consolidation. This was used to calculate coefficient of lateral earth pressure, K (which is the ratio of horizontal to vertical effective stress). The results of the laboratory testing program found that K was relatively independent of the percentage of fines present in the SB mix. It also showed that backfill angle of internal friction and k of the backfill decreased with increased fines content. The results of the laboratory testing program were used to model the vertical stress distribution in deep walls. An analytical model (discrete model) and a coupled seepage stress-strain finite element model (FEM) were used to predict vertical stress changes with time and depth for the different backfill materials. The primary conclusion of this research is that slurry wall backfill arching or “hang-up” significantly delays the magnitude and timing of vertical stress build-up in backfill. This loss of vertical stress results in backfill with lower density and higher hydraulic conductivity. The situation was found to be most critical for deep narrow slurry walls. Any advantage in using a coarser graded backfill was offset by higher backfill hydraulic conductivity. The net result is that the upper portions of slurry walls may not be able to achieve their hydraulic conductivity objectives as soon as expected, if at all. In addition, the backfill in the upper portion of the trench may be susceptible to chemical attack and osmotic consolidation. Construction of a 2 m high surcharge berm over the slurry wall was found to increase vertical effective stress and result in significantly lower (2 to 8 times) hydraulic conductivity values in the top 5 metres of the trench. The final hydraulic conductivity (k) at a depth of 5 m was approximately 75 % lower with a surcharge berm. Thus, construction of a surcharge berm over the slurry wall helps to satisfy the k requirement for SB walls and lowers the risk of osmotic consolidation

Utilization of EPS Beats and Polypropylene Fiber in Controlled Low Strength Material

Controlled low-strength material (CLSM) is a self-levelling cementitious material. It is not concrete nor soil-cement, however, it possesses properties similar to both. CLSM is widely used as a replacement for soil-cement material in many geotechnical applications such as structural backfill, pipeline beddings, void fill, pavement bases and bridge approaches. This paper study potential possibility of polypropylene fiber in CLSM. Harden and fresh properties compressive strength , flowability  and density for the proposed CLSM were investigated. This CLSM mix design with different percentage of polypropylene fiber and pond ash, cement and water. EPS beats and polypropylene add 0 %, 0.5%, 1.0% and 1.5% of total weight is added in CLSM MIx. Results show that the CLSM incorporating EPS beats and polypropylene satisfies compressive strength requirement as per the requirements of ACI committee 229. polypropylene  decreases the flowability of CLSM mix and at the same tine by adding EPS beats the density of CLSM mix are reduce which become lightweight CLSM mix. from this it can conclude that polypropylene fibers is less effective in CLSM mix and EPS beats make CLSM mix lightweight which create lightweight CLSM mix applicable for filling application

A large goaf group treatment by means of Mine Backfill Technology

There are few studies on the management methods of large-scale goaf groups per the specific surrounding rock mass conditions of each goaf. This paper evaluates comprehensively the stability of the multistage large-scale goaf group in a Pb-Zn mine in Inner Mongolia, China, via the modified Mathews stability diagram technique. The volume of each goaf to be backfilled was quantitatively analyzed in the combination of theoretical analysis and three-dimensional laser scanning technology. The corresponding mechanical characteristics of the filling were determined by laboratory testing while formulating the treatment scheme of the large goaf group using the backfill method. The applicability of the treatment scheme using the backfill was verified by the combination of the numerical results of the distribution of the surrounding rock failure zone and the monitored data of the surface subsidence. The research results and treatment scheme using the backfill can provide a reference for similar conditions of mines worldwide.National Natural Science Foundation of China (NSFC) U1906208 China Postdoctoral Science Foundation 2021MD703874 2021M702015 Scientific Research Start-Up Project of University Talent Introduction 205012100

Paste Fills Technology in Condition of Estonian Oil Shale Mine

Oil shale mining and processing industry in Estonia produce a wide assortment of waste could be considered as available fill materials. Waste rock which is not usable in civil engineering and road building may be used for backfilling underground mines. Paste fills technology, which has several benefits, requires careful selection of oil shale waste rock aggregates and other carbonate stones. The laboratory tests and theoretical investigations were made for determination the applicability of limestone and dolostone aggregates as backfill material. It enables to determine the feasible parameters of aggregates from oil shale mining waste rock. Analysis showed that limestone aggregates of Estonian oil shale mines suit best for backfill technology in conditions

Design and Construction of a Soil Bentonite Slurry Wall Around an Operating Facility Superfund Site

A soil bentonite slurry wall was designed for an NPL site to stop further migration of chemicals in a complex aquifer system, and to facilitate the removal of possible chemical sources from saturated zones beneath the site. Pumping from within the slurry wall will maintain inward and upward hydraulic gradients and thus stop further lateral or vertical migration of chemicals from the contained area. The slurry wall was constructed under an exceptionally detailed Quality Assurance; Quality Control review by the Contractor and two independent consulting firms. Ground movements, vibration levels and opacity of dust produced during construction were monitored for compliance with design specifications. It was made a condition of the contract that no hazardous material could leave the site. Federal regulations required all persons involved in site work to have health and safety training. Careful planning and close liaison between the Owner, Engineer and Contractor has enabled the slurry wall to be constructed in a business park environment around an operating manufacturing facility without disruption to production