ABSTRACT This research evaluated the application of post consumer glass as a cementing agent in underground mine backfills. The underlying theory indicates that glass is pozzolanic and, when used in finely divided form, reacts as an activator to generate binding products, thus contributing to the development of backfill strength. The objective of the research was to evaluate the strength performance of backfills when Normal Portland Cement (NPC) is replaced with various percentages of post consumer glass. The research evaluated the performance of backfills prepared using tailings from three candidate mines, namely Stobie, David Bell and Kidd Creek. Each backfill was prepared using unique recipes, and the strength and other properties were evaluated at cure times of 7, 14, 28, 56, 112 and 224 days. Laboratory work involved visual, physical and chemical material characterization followed by strength evaluations. Results of strength assessment reveal that glass, when incorporated as part of the binder in backfill development is reactive, and can contribute to the strength of backfill. Further analysis of the results also indicated that the reactivity of glass may be affected by the incorporation of slag within the recipe, the availability of lime and the level of hydration of the binders. The research concluded that, at 15 % glass replacement of NPC, backfill prepared with David Bell tailings, NPC and glass can achieve improved or equivalent strength performance compared to backfill prepared with David Bell tailings and NPC. NPC and slag outperformed backfills prepared with NPC, slag and glass at all replacement levels, using tailings from Kidd Creek and Inco-Stobie. However, future work should be designed to maximize the effect of specific pozzolan (for example glass) and material properties (aggregates) on backfill strength performance. / Thesis (Master, Mining Engineering) -- Queen's University, 2008-01-29 15:09:30.281

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2013. / Submitted by Alaíde Gonçalves dos Santos (alaide@unb.br) on 2014-06-02T15:23:43Z No. of bitstreams: 1 2013_LucasAlbertoVissottoJunior.pdf: 10786095 bytes, checksum: 3f5b3f8971d2d1ae09a7d2b2066a4338 (MD5) / Approved for entry into archive by Guimaraes Jacqueline(jacqueline.guimaraes@bce.unb.br) on 2014-06-04T11:28:08Z (GMT) No. of bitstreams: 1 2013_LucasAlbertoVissottoJunior.pdf: 10786095 bytes, checksum: 3f5b3f8971d2d1ae09a7d2b2066a4338 (MD5) / Made available in DSpace on 2014-06-04T11:28:08Z (GMT). No. of bitstreams: 1 2013_LucasAlbertoVissottoJunior.pdf: 10786095 bytes, checksum: 3f5b3f8971d2d1ae09a7d2b2066a4338 (MD5) / Este trabalho apresenta uma análise tridimensional de mina subterrânea com ênfase na interação entre maciço rochoso e preenchimento (backfill), considerando o comportamento mecânico do maciço enquanto ocorre o progresso das escavações e da disposição com aumento da tensão confinante e endurecimento do módulo de deformabilidade. Foi realizado o monitoramento do caso de estudo da Mina Cuiabá e comparados os resultados com as modelagens tridimensionais. O tipo específico de lavra estudada foi o cut and fill com orientação sub vertical. Nas modelagens foi analisado o processo de endurecimento do modulo de deformabilidade do backfill, de acordo com a etapa do ciclo de lavra. Os resultados do monitoramento e das modelagens mostraram que a adoção pelo backfill contribui de modo ativo para a estabilidade e segurança da mina. O aumento da tensão confinante devido ao endurecimento do backfill aumentou a interação mecânica com o maciço. Um aspecto sócio ambiental importante relaciona-se ao preenchimento das escavações com rejeito que tendem a mitigar os impactos ambientais, principalmente pela considerável redução dos volumes de rejeitos dispostos em superfície. _______________________________________________________________________________________ ABSTRACT / This study presents a numerical and experimental three-dimensional analysis of the interaction rock mass / backfill, considering the mechanic behavior of rock mass, during the process of excavation and backfill disposal, with increase of the confining stress and the module deformability hardening. The study case of Mine Cuiabá was monitored and the results were compared with the three-dimensional models. The specific type of mine studied was the cut and fill with sub vertical orientation. In the simulations was considered the module of backfill deformability that varies according to the stage of the exploration cycle. The disposal via backfill technology was simulated and monitored, which the results showed a positive contribution with the stability and safety of mine. The increase of the confining stress due to the hardening of backfill deformability module improved the interaction rock mass and backfill. This study showed that the backfill disposal linked to underground exploration mine tends to mitigate the environmental impacts in the mine.

This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

This thesis presents the results of an investigation of factors which influence the geotechnical properties of frozen mine backfill (FMB). FMB has extensive application potential for mining in permafrost areas. The uniaxial compressive strength (UCS) of hardened backfill is often used to evaluate mine backfill stability. However, the deformation behaviour and stiffness of the FMB are also key design properties of interest. In this thesis, uniaxial compressive tests were conducted on FTB and FCPB samples. Information about the geotechnical properties of FMB is obtained. The effects of FMB mix components and vertical compression pressure on the geotechnical properties of FMB are discussed and summarized. An optimum total water content of 25%-35% is found in which the strength and the modulus of elasticity of the FTB are 1.4-3.2 MPa and 35-58 MPa, respectively. It is observed that a small amount (3-6%) of cement can significantly change the geotechnical properties of FTB.

The Renström mine, Boliden Mineral AB, uses, among other methods, the Transverse long hole stoping method with backfill. The mine uses a cement-stabilized hydraulic fill (CHF), which is a mixture of enrichment sand, cement and water. The most important factor in relation to strength is the water cement ratio. Today, only tests have been performed on the surface and in laboratory tests. The purpose of this work is thus to study the possibility of using other types of methods that can give a better understanding of the strength of the entire filling volume. Studies on backfill containing Portland cement and sulphur have shown that the UCS strength decreases with time, which can cause problems for the mine. A leaching method (MRM leaching test) used to evaluate potential sulphide soils has been used in this study on the backfill to investigate the sulphurs impact on the cement mixture. Electrical conductivity, pH, and redox potential were investigated and gave similar results, where the higher cement levels (8%, 10%, and 12%) were indistinguishable while the lower cement content (4%) differed significantly from the other levels. This probably indicates that the higher cement levels have a greater resistance to the influence of the sulphur. The most promising results were given when the method was used on enrichment sand alone. The linear lowering of the pH value of the enrichment sand, from pH 4.9 to about pH 3, point to that the enrichment sand contains large amounts of sulphur, as previously chemical analysis has shown. This suggests that the method can best be used in an early stage before the sand is mixed with cement. The strength results on the samples showed a strength after 7 days that was in line with the 90-day strength. However, all 90 day samples had decreased in strength during the time sequence, which may be an effect of the sulphur content, but should be further investigated to be determined. The smaller size of the samples was also experienced as a challenge during the temperature measurements due to small temperature variations and environmental effects. A maturity method for predicting the strength of concrete called "The maturity method" has been investigated in this study. To determine the strength maturity relationship, both the temperature related to time and the equivalent age must be evaluated. The study showed that the method cannot be used on the mine's backfill without first making adjustments related to the lower cement content used in the backfill compared with concrete constructions, since it is not possible to determine the strength growth in the early stage as the method requires.

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Advancements in technology in mining have allowed previously unfeasible ore bodies to be developed. Paste backfill is one technological advancement that has allowed for the development of high-grade, low tonne production when employing the cut and fill mining method. Goldcorp Inc.'s Red Lake Mine currently utilizes this method and is the site for the study of this thesis. Paste backfill (paste) is defined as a mine backfill material that consists of eighty-five percent solids by weight and does not bleed water when placed often consisting of between two and fifteen percent Portland cement by weight. A paste barricade or paste fill fence is a constructed barricade whose purpose is to retain backfill within a mined out stope. The construction of the barricade varies with different operations, for Red Lake Mine the barricade consists of an anchored rebar skeleton covered with an adequate thickness of shotcrete. The majority of the applicable barricade research focuses on hydraulic fill barricades in open stope mining. The barricade pressures in these instances are much larger than those experienced in paste backfill barricades. As such, the current paste loading theory is based on material with a different loading mechanism. Although some research is currently underway, the majority of the barricade research is based on brick barricades and not the shotcrete, rebar skeleton as used at Red Lake. Catastrophic failures of barricades can occur without an understanding of the loading mechanisms. Based on the catastrophic risk, this thesis provides an investigation into the behaviour of the paste backfill and paste barricades at Red Lake Mine in order to provide a safe, cost effective design of paste barricades. This thesis develops an understanding of paste loading mechanisms and barricade capacity derived from a field study of nine instrumented fill fences at Red Lake Mine. Eight of thefences were instrumented to monitor the reaction strain in the fence and the applied pressures during standard production paste pours, the ninth fence was a controlled destructive test that determined the ultimate capacity of the fence. The data for these tests were gathered in real time and was subsequently reduced to assist in analysis. Yield Line Theory, Rankine Theory, strain induced stress, stress vs. strain analysis and numerical modeling were used to develop an understanding of the paste loading mechanisms and the capacity of the paste fill barricades. The analysis determined that the paste backfill behaves as a Rankine-like soil in the initial stages of loading with an average coefficient of lateral earth pressure, Ka, of 0.56. The destructive test determined that the yielding stress of a paste barricade is approximately 100 kPa. Further findings from the research determined that the rate of placement of paste does effect the loads applied to the fence and that the largest pressures exerted on the fill fence occur when paste lines were flushed with water at the end of the pour. This thesis provides an understanding of the paste loading and fill fence interaction with respect to failure. Based on this research the Red Lake Mine should be able to increase production without increasing risk to mine personnel by quantifying the overall loading and strengths of the fill barricade.

From previous research, it has been proven that rock roughness and closure are two important factors for stability of backfilled stope and exposed backfill. In order to estimate the important parameters of roughness, several investigations have been conducted in other scientific fields to study roughness. The results showed that the important roughness parameters are application-dependent. In geology and rock mechanics the Joint Roughness Coefficient (JRC) is a critical factor that incorporates the roughness in stability problems. Although JRC is widely used, it is very subjective and highly depends on the experience of the individual conducting the analysis. During the last several decades there were attempts to use different methods such as fractal geometry, Fourier analysis, analytical methods, etc. to convert a random surface profile into a JRC. The goal of the current research is to estimate with greater accuracy the contribution of roughness to the shear strength of the interface at the paste-rock contact when backfilling. Four hundred and fifty backfill samples were constructed and tested in a shear box. The variables of the tests are three: binder percentage, roughness and cure time. From the test results the importance of each of those parameters to the final shear strength of the paste-rock interface was estimated. The normal stress that acts on the samples is also a critical factor. From the tests that were tried, it was concluded that there are limits in normal stress for which roughness is important. / Thesis (Master, Mining Engineering) -- Queen's University, 2009-08-27 16:07:21.916