Strength Of Tailings Research Articles

Early hydration and mechanical performance of composited cementitious system prepared from high temperature calcined molybdenum tailings

To improve the recycling of solid waste and achieve the secondary utilization of waste resources, this study investigates the preparation of molybdenum tailings composited binders by high temperature calcination using molybdenum tailings, limestone, bauxite, and iron concentrate powder. Besides, to explore the mechanical properties of the new molybdenum tailings composited binders, a molybdenum tailings composited mortar was prepared. The mechanical properties, micro performance and hydration mechanism of the new molybdenum tailings composited binders were studied. Finally, the carbon dioxide emission of green molybdenum tailings composited binders/molybdenum tailings composited mortar was evaluated by the life cycle assessment method. The results show that the compressive strength of molybdenum tailings composited binders gradually increases with the increase of calcination temperature. When the calcination temperature is 1350 °C, the compressive strength and flexural strength at 28 days are 44.17 MPa and 7.56 MPa, respectively, which are 3.65 % and 4.63 % higher than control group made by P·O 42.5 cement. The early strength of molybdenum tailings composited binders increases slowly, and the later strength increases rapidly. In addition, there is more C2S in the matrix, resulting in a slow hydration heat rate and low cumulative hydration heat. Compared with other groups, the hydration kinetic parameters and hydration rate of molybdenum tailings composited binders under 1350 °C were the lowest. The main hydration prodcuts of molybdenum tailings composited binders are C-S-H, calcium hydroxide, and Aft gels. Compared with P·O 42.5 cement paste and mortar, the carbon dioxide emission of molybdenum tailings composited binders/molybdenum tailings composited mortar is reduced by 42.82 % and 29.08 %, respectively, which can indicate that the new binders can produce less carbon dioxide. Overall, this study can provide new ways for the development of the new binder mixed with plenty of molybdenum tailings, and offer a novel way for recycling the molybdenum tailings, and also present some valuable experimental results for the application of molybdenum tailings in infrastructures.

Response Surface Design Models to Predict the Strength of Iron Tailings Stabilized with an Alkali-Activated Cement

Tailing storage facilities are very complex structures whose failure generally leads to catastrophic consequences in terms of casualties, serious environmental impacts on local biodiversity, and disruptions in the mineral supply. For this reason, structures at risk must be reinforced or decommissioned. One possible option is its reinforcement with compacted filtered tailings stabilized with binders. Alkali-activated binders provide a more sustainable solution than ordinary Portland cement but require an optimization of the tailing–binder mixture, which, in some cases, can lead to a substantial experimental effort. Statistical models have been used to reduce the number of those experiments, but a rational design methodology is still lacking. This methodology to define the right mixture for a required strength should consider both the mixture components and in situ conditions. In this paper, response surface methods were used to plan and interpret unconfined compression strength test results on an iron tailing stabilized with alkali-activated binders. It was concluded that the fly ash content was the most important parameter, followed by the liquid content and sodium hydroxide concentration. From the obtained results, several statistical models were defined and compared according to the definition of a strength prediction model based on a mixture index parameter. It was interesting to observe that models with the porosity cement index still provide reasonable adjustment even when different tailings’ water contents are considered.

Compressive strength, durability, and resilient modulus of cement-treated magnetite and hematite iron ore tailings as pavement material

The extraction and processing of iron ore produce significant amounts of mine tailings, causing environmental problems that require storage in reservoirs or dams. Using these materials in construction helps minimize their adverse impacts. This study analyzed the geotechnical properties of Magnetite and Hematite iron ore tailings (MIOT, HIOT) from the Golgohar mine in Sirjan, Iran. Two IOTs were compacted using the Standard Proctor technique after being treated with 5, 7, and 9 % Portland cement. Following curing time, treated samples were tested at different stress levels for resilient modulus. Based on the results, to meet strength and durability requirements, cement-treated MIOT needs 9 % cement. Contrastingly, only 5 % of the cement for cement-treated HIOT met the criterion. The resilient moduli of untreated MIOT and HIOT materials heavily rely on the confining pressure, resulting in a minimal decrease in modulus by increasing deviatoric stress. The effect of cement on resilient modulus is more pronounced in high confining stresses than in low confining stresses in MIOT and HIOT materials. A comparison of different non-linear models showed that ‘Universal’ model is the best fit for laboratory results of cement-treated MIOT and HIOT materials, as it accounts for hardening and softening behavior.

Tensile strength and dilative characteristics of compacted unsaturated clay-sized metalliferous tailings for bulk earthworks

Tensile strength and dilative characteristics of compacted unsaturated clay-sized metalliferous tailings for bulk earthworks

Study on the micro-rheological properties of fly ash-based cement mortar

Aiming at the shortcomings of poor rheological properties and low strength of tailings filling mortar, solid waste materials such as fly ash, steel slag, and desulfurization ash were introduced to improve the filling mortar. The Response Surface Methodology (RSM) was used to design the test ratios to determine the significance of the effect of fly ash, steel slag and desulphurization ash on the physical properties of the mortar. The rheological characterization law of filling mortar was studied based on macroscopic L-tube test. The mechanism of filling mortar improvement was analyzed by Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS) and other microscopic tests. The results show that the response-factor model fit regression is significant, with the highest model satisfaction at 12 % fly ash dosing, 15 % steel slag dosing, and 10 % desulfurization ash dosing. The self-flowing extension diameter of the mortar is 15.34 cm, and the 3d and 28d strengths are 0.58 MPa and 3.24 MPa, respectively. Fly ash has effectively improved the phenomenon of mortar segregation and precipitation, and the yield stress of mortar is reduced by 35.1∼64.9 % when the dosage is 8∼12 %. The fractal dimension and mortar workability are positively correlated with fly ash admixture. Fly ash incorporation will gradually consume the calcium hydroxide (CH) to generate alumina ferrite (Aft) and calcium silicate hydrate (C-S-H), which reduces mortar porosity and promotes long-term strength growth. The research results not only realized the effective utilization of solid waste resources, but also significantly improved the performance of the filler and ensured the safe production of the mine.

Mechanics and microstructure analysis of geopolymer utilizing ilmenite tailing and metakaolin powder as alkali-activated materials

Geopolymers derived from bulk solid waste are considered ideal substitutes for cement-based materials in developing environmentally friendly construction materials. The utilization of solid waste tailings powder as a precursor for alkali activation of geopolymer can enhance the mechanical characteristics of geopolymer. This study conducted extensive experimental studies on the compressive strength, flexural strength, SEM microstructure, thermogravimetric curve, and variable influence of alkali-activated ilmenite tailings (IT) geopolymer mortar, using the liquid-solid ratio and the number of tailings as variables. An analysis was conducted on the mortar's mechanical characteristics, microstructure, and machine-learning properties. Furthermore, the impact of different atomic ratios on the structure and characteristics of geopolymer mortars was also examined. The test results revealed that the metakaolin-iron titanium tailings geopolymer, when doped with 10% ilmenite tailings, exhibited a compressive strength of 72.30MPa at 14 days. Similarly, the flexural strength of the geopolymer reached 4.76MPa at 14 days when doped with 30% ilmenite tailings. XRD analysis showed that Magnesiohornblende particles Mg-F-A-S-H and C-A-S-H gel had positive and negative correlations, respectively, with the tailings doping level. TG results indicated that the specimens exhibit enhanced thermal stability following treatment with tailings. SEM analysis revealed that combining ilmenite tailings with metakaolin formed Me-(F)-A-S-H gels. The examination of surface porosity, pore shape, and unreacted material determined that adding ilmenite tailings increased the Si/Al and Fe/Si ratios, enhancing the transformation of the lamellar structure to the three-dimensional disordered gel mesh structure. Additionally, the tailings contributed a significant amount of Ca, elevating the Ca/Na ratio (0.1−0.6) and triggering calcium precipitation within a Ca/Si range of 0.03−0.2. This increase in calcium led to a decrease in the sample's strength as the curing time was extended. Based on prior research and the application of the Gray Wolf optimization algorithm in extreme learning, a clear negative correlation was identified between the liquid-solid ratio and strength. Furthermore, increasing the Si/Al ratio enhanced the geopolymer's strength, while an extended curing time negatively correlated with strength. The impact of tailings mixing was deemed insignificant when the tailings amount did not exceed 20%. Geopolymers may derive significant environmental and industrial benefits from the improvement of their mechanical properties, thermal stability, and optimization using machine learning.

Analysis of unconfined compressive strength and environmental impact of MICP-treated lead-zinc tailings sand instead of sand as embankment material

Tailings can be used as embankment materials instead of sand. However, they contain large amounts of heavy metal pollutants, which can lead to groundwater pollution. In this study, (lead-zinc) Pb-Zn tailings with five particle sizes and Sporosarcina pasteurii were used as test materials. Combined with the unconfined compressive strength (UCS) and leaching of heavy metal pollutants from Pb-Zn tailings, the feasibility of applying microbial induced carbonate precipitation (MICP)-treated Pb-Zn tailings to embankment materials was analysed from the perspective of strength and environmental performance. The results showed that the UCS and carbonate content of the specimens made of Pb-Zn tailings treated using MICP decreased with a decrease in the number of Pb-Zn tailing particles. The pH value of the leaching solution after MICP treatment of Pb-Zn tailings sand was stable at 7.83–8.03, and the fixation rate of metal ions was 90.28 %–100 %. FTIR, X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy tests showed that after the Pb-Zn tailings with particle sizes less than 100 mesh were treated using MICP, the number of carbonate crystals, crystal uniformity, and crystal overlap on the surface of the sample were considerably higher than those of the tailings with particle sizes greater than 250 mesh. The compressive strength and environmental performance of Pb-Zn tailings with particle sizes less than 100 mesh treated using MICP are good, and they are more suitable for embankment materials.

Mechanical Properties and Hydration Mechanism of Iron Tailings–Cement-Based Supplementary Cementitious Materials

The preparation of cement-based supplementary cementitious materials is an important method for the efficient use of iron tailings and the reduction in CO2 emissions. The aim of this study is to improve the reactivity of iron tailings by mixing them with steel slag, slag, and fly ash through orthogonal tests to solve the problem that iron tailings cannot be utilised on a large scale. The compressive strength, hydration products, and microstructure of the iron tailings–cement-based supplementary cementitious materials were investigated using ICP-OES, XRD, TG, FTIR, and SEM. The results revealed that each solid waste raw material played a distinct role in the hydration reaction. In the iron tailings–cement-based supplementary cementitious materials system, steel slag provided Ca2+, OH−, and Si4+ ions, slag provided Ca2+ and Al3+ ions, fly ash contributed a significant amount of Ca2+ and Al3+ ions, and iron tailings offered more nucleation sites and some Si4+ ions for the hydration products. Moreover, there was a synergistic effect among these four materials, promoting the formation of hydration products such as ettringite, C-(A)-S-H gels, and others. When the proportion of IOTs:SS:FA:SL was 9:8:8:2, the highest 7 d compressive strength of cementitious material was 24.8 MPa. When the proportion of IOTs:SS:FA:SL was 9:6:8:4, the highest 28 d compressive strength of cementitious material was 35.0 MPa. This study provides a comprehensive solution for the utilisation of iron tailings and contributes to the high-value green utilisation of solid waste.

Enhancing workability, strength, and microstructure of cemented tailings backfill through mineral admixtures and fibers

The study investigates the enhancement of cemented tailing backfill (CTB) performance and cost reduction through the systematic examination of CTB with various fibers (polypropylene, basalt, and straw) and mineral additives. The impact of fiber, rice husk ash, and fly ash on CTB's physical attributes, workability, and microstructure is thoroughly analyzed. The results showed that with the increase of fly ash content, slump increased by 3.77 %, and the bleeding rate, initial setting time and final setting time increased by 10.33 %, 24.67 % and 7.71 %, respectively. Conversely, as the rice husk ash content rises, slump decreased by 1.89 %, while bleeding rate, initial and final coagulation time decreased by 10.33 %, 4.93 % and 5.17 %, respectively. The incorporation of polypropylene fiber, basalt fiber and rice straw fiber results in a reduction in slump by 5.97 %, 5.22 % and 3.73 %, and a decrease bleeding rate decreased by 29.18 %, 27.88 % and 22.86 %, respectively. Moreover, an increase in the content of three kinds of fiber leads to prolonged initial and final setting time of slurry. Fly ash or rice husk ash additions improve CTB compressive strength, with the optimum fly ash content at 15 %. Combining fly ash and rice husk ash further enhances compressive strength, with an optimal content of 16 %. Polypropylene, basalt, and rice straw fiber additions significantly boost sample compressive strength, with an optimal fiber content of 0.6 %. Polypropylene or rice straw fibers inhibit main crack extension, with polypropylene fiber outperforming in crack resistance at 0.6 % fiber content. Increased fly ash or rice husk ash improves microstructure density and forms a stable network support system in CTB. The distribution of polypropylene or rice straw fibers transitions from sporadic to dense, exhibiting bending deformation characteristics indicative of load-bearing and dispersing roles.

Variability of the undrained strength of the plastic tailings from the Germano dam in Mariana, Brazil

Mining tailings may be divided in non-plastic (sand, silty sand, or sandy silt tailings) and plastic (fine tailings, usually mixtures of silt and clay-sized particles). The understanding of the behavior of these materials is a great geotechnical challenge because of their wide variations in mineralogy, physical–chemical, and geotechnical characteristics. Sand tailings have been widely studied in the last decades because they are often susceptible to liquefaction, and they usually constitute the beach of the tailings dam which is the most important zone for stability analysis in upstream dams. However, the study of the characteristics and the strength of the plastic tailings is also important since layers of plastic tailings are sometimes found in the midst of the sand tailings. The aim of this article is to study the normalized undrained strength ratio (su/σ′v) of plastic tailings of the Germano dam in Mariana, Brazil, and to present a criterion developed for their identification. The method consisted of analyzing and scrutinizing Piezocone (CPTu), Field Vane (FV) tests, and the water levels. An extensive review of the iron ore plastic tailings properties was also performed. A total of approximately 900 occurrences of plastic layers were analyzed. The results included the discovery of perched water tables and significant vertical downward flow in some locations. The conclusion is that su/σ′v histograms are well fitted by lognormal distributions and the layer thickness influences the undrained strength. Moreover, the strengths are relatively low (for example, su/σ′v = 0.11 on average for plastic layers with thickness of 1.0 m or more).

Linking laboratory quasi-steady state strengths to field scale performance of tailings

Current state of practice for the assessment of liquefied strengths of tailings relies primarily on empirical or semi-empirical correlations based on penetration testing. That is, despite liquefied strength being arguably the most important strength parameter for the design of brittle tailings storage facilities, there is much less success or acceptance of the use of laboratory element tests to support strength selection compared to other forms of strengths inferred in geotechnical engineering. This is particularly the case for tailings at a state near or slightly dense of the critical state line (CSL) for which there is ample evidence of field-scale flow liquefaction but where laboratory element tests often behave in a manner inconsistent with such field-scale response – at least at large strains. The current paper examines the quasi steady state (QSS) strength of sands and tailings for which the CSL has been measured, linking the observed strengths to inferred in situ behaviour through the state parameter. Particular focus is placed on QSS strengths obtained from simple shear tests carried out within a hollow cylinder torsional shear system where the stress state in the test is a better representation of in situ below-slope conditions that the triaxial compression test. In particular, the marked effect of intermediate principal stress on the QSS in sands is highlighted. Alternatively, the negligible anisotropy seen in a sandy silt gold tailings, and the potential implications in the context of QSS strengths and field-scale behaviour, are examined and emphasised.

Safety assessment in dams due to downstream slope anomalies

Recent cases of tailings dam failure in Brazil have demonstrated in the current methods of safety assessment of these structures. One of the most employed methods is the evaluation through routine inspections and audits, but this method is considered non-deterministic and affected by the expertise of the evaluator. This paper presents the results of numerical simulations of anomalies commonly found in safety inspections to measure the impact of these anomalies on the dam safety factor. The study was limited to numerical simulations of five types of dams (three downstream and two upstream dams), with varying embankment and tailings strength parameters, simulating different magnitudes of downstream slope anomalies (cracks, scour, and resurgence), totaling a sample space of 270 analyses. The results show that there were average reductions in safety ranging from 4% to 10% for scour simulations, 8% to 25% for resurgence, and 9% to 24% for cracking. The sample standard deviation of the analyses ranged from 8 to 12%. It was also observed that the combined effect of the anomalies showed proportional overlapping effects in reducing the range of safety. It was concluded that the simulated failures are important variables to be evaluated in inspections, not only for demonstrate deviations in the operation and maintenance of structures, but also to predict the magnitude of these failures in dam designs.

Experimental study on the effect of cementation curing time on MICP bio-cemented tailings

Tailings dam break and leakage accidents usually threaten the safety of people around the mining area. In addition, tailings leakage seriously pollutes the surrounding environment. In view of the above problems, the tailing sand is solidified based on the microbial induced calcite precipitation (MICP). This method can not only enhance the strength of tailing sand, but also solidify heavy metals in tailings. In order to optimize the curing time of MICP bio-cemented tailings, improve the strength and cost-effectiveness, this study used the layered injection method to cement the tailings. Combined with the unconfined compressive strength, calcium carbonate content and heavy metal leaching effect of MICP bio-cemented tailings, the effect of MICP curing time on bio-cemented tailings was analyzed. The results showed that the curing time of MICP bio-cemented tailings has a great influence on the strength of tailings, and has little effect on the fixation of heavy metals in tailings. The curing time of the optimized MICP biocemented tailings is 10 days. The unconfined compressive strength of the MICP bio-cemented tailing sand specimen is 1.01 MPa. When the cementation curing time is greater than 10 d, the cementation curing time will no longer be the main factor affecting the MICP bio-cemented tailings. After the MICP bio-cemented tailings samples were leached for 5 days, the fixation rates of Pb2+, Zn2+, total Fe, Mn2+, Cu2+, Cd2+ and total Cr in the leaching solution were 100%, 100%, 100%, 94.80–98.45%, 100%, 100%, 93.34–95.56%, respectively. The results of FTIR, XRD, SEM and EDS showed that when the tailings were cemented and solidified many times the cementation liquid metabolized by Sporosarcina pasteurii was mainly used for the growth of existing calcium carbonate crystals rather than the formation of new calcium carbonate crystals. The deposition of these larger calcium carbonate crystals can stably fill the gaps between the tailings particles, cement the tailings particles together and improve the strength of the tailings.

Mechanical and Microstructural Response of Iron Ore Tailings under Low and High Pressures Considering a Wide Range of Molding Characteristics

The dry stacking of filtered tailings is an option to deal with safety-related issues involving traditional slurry disposition in impoundments. Filtered tailings can be compacted to pre-define design specifications, which minimizes structural instability problems, such as those related to liquefaction. Yet, comprehending the tailing’s response under various stress states is essential to designing any dry stacking facility properly. Thus, the present research evaluated the mechanical response of cemented and uncemented compacted filtered iron ore tailings, considering different molding characteristics related to compaction degree and molding moisture content. Therefore, a series of one-dimensional compression tests and consolidated isotropically drained triaxial tests (CID), using 300 kPa and 3000 kPa effective confining pressures, were carried out for different specimens compacted at various molding characteristics. In addition, changes in gradation owing to both compression and shearing were evaluated using sedimentation with scanning electron microscope tests. The overall results have indicated that the 3% Portland cement addition enhanced the strength and stiffness of the compacted iron ore tailings, considering the lower confining pressure. Nevertheless, the same was not evidenced for the higher confining stress. Moreover, the dry-side molded specimens were initially stiffer, and significant particle breakage did not occur owing to one-dimensional compression but only due to shearing (triaxial condition).

Effect of curing temperature on the mechanical properties and pore structure of cemented backfill materials with waste rock-tailings

In order to reduce the cost of deep mining in Guangxi Gaofeng Mine, the feasibility of underground waste rock used for backfill and was analyzed. The tailings and waste rock taken from Gaofeng Mining Industry had been selected for comparative tests, different ratio of waste rock and tailings and curing temperatures were set, the effect of different conditions on the porosity and strength of waste rock and tailings cemented backfill was investigated. Study indicates that the macroscopic mechanical properties of the backfill are the external response of its microstructure, and the change of the microstructure of the backfill is the essential reason for the change of its mechanical properties. when the waste rock-tailings ratio is 6:4 or 7:3, the USC increases with the increase of the curing temperature; while the waste rock-tailings ratio is 8:2 or 9:1, the USC tends to increase and then decrease with the increase of the curing temperature, where 40℃ is the turning point. In deep mines of Gaofeng Mine, ratio of waste rock and tailings of 9:1 is preferred when the temperature is around 40 °C, while ratio of waste rock and tailings of 6:4 is more effective at deeper depths around 50 °C.

Research on Compressive Tests of Iron Tailing and Cement-Modified Earth Materials from Northwest China

The strength of earth-modified materials is an important mechanical indicator of raw soil building materials. Iron tailings are a rich mineral waste resource with basic properties similar to river sand and can be used as a modified material for raw soil construction. To increase the utilization rate of iron tailings and improve the mechanical properties of earth materials, modification of earth materials were analyzed using iron tailings and cement. Through a single lattice theory design method, 10 different blending ratios of modified earth specimens were designed, with each group comprising six 100 mm cubic specimens. Earth specimens were used as the control group and compression tests carried out under standard curing conditions, with analysis of the failure mode, compressive strength, deformation, and load–displacement curve for each specimen. Also, the reasons for specimen failures were examined, including the influence of strength, dispersion, and implications of load–displacement curves. The optimal mix ratio of modified materials was determined using frequency domain analysis method. The results showed that the load–displacement curves of materials with different material ratios were basically similar and the slope and discreteness of the curves quite different. Increased tailings and cement content improved the compressive strength of earth materials and increased the discreteness of the material. Through frequency analysis, it was obtained that when the content of tailings was 12.1%–19.5%, cement content 13.9%–19.1%, and earth 65.5%–69.9%, there was a 95% of the guaranteed rate of compressive strength of iron tailings and cement-modified earth materials between 6 and 9 MPa. Iron tailings can, thus, be used as the preferred material for modifying earth materials; single lattice theory can be used as the design method for mixing experiments, and frequency domain analysis can be an effective calculation method for optimizing mixing design. Adding cement and iron tailings to modify the raw soil formula can provide reference for the selection of basic materials for raw soil construction.

Cavity expansions in two silty tailings with high degrees of saturation and a comparison to CPT results

Tailings, being mixtures of water and soil-sized particles, and sometimes air, are waste products generated by mining. They are stored on sites, often contained by embankments, forming what are known as tailings storage facilities (TSFs). Assessments of the state and strength of tailings inside a TSF may involve in situ tests, especially the cone penetration test (CPT) and occasionally the pressuremeter test (PMT). Cavity expansion theory may assist the interpretation of these tests. The coexistence of air and water in the pore space means the tailings is unsaturated and gives rise to a suction. The suction, and the extent to which air and/or water can drain through the pores, affects the cavity expansion results as well as CPT and PMT results. The cavity expansion problem is solved here considering four possible drainage conditions, constant suction, constant water mass, constant contribution of suction to the effective stress, and a constant air and water mass (closed system). It is reasoned that solutions for a closed system are relevant to the interpretations of CPTs and PMTs when < 15 % of the tailings volume is occupied by air, and that the constant effective stress condition (which is a close approximation to a constant water mass condition) is relevant when larger air volumes are present. By considering CPT data it is observed that linear proportionalities exist between effective cone penetration resistances and cavity wall pressures. The cavity expansion results are then converted to equivalent CPT results and used to construct charts which relate the normalised cone penetration resistance to the initial state parameter. The charts have use for unsaturated conditions and a variety of air volume fractions, as well as saturated conditions when the cone penetration rate is slow enough so drained conditions prevail or fast enough so that undrained conditions prevail.

Experimental Study on the Solidification of Uranium Tailings and Uranium Removal Based on MICP

The governance of uranium tailings aims to improve stability and reduce radionuclide uranium release. In order to achieve this goal, the uranium removal solution test and uranium tailings grouting test were successively carried out using microbially induced calcium carbonate precipitation (MICP) technology. The effect of MICP on the reinforcement of uranium tailings and the synchronous control of radionuclide uranium in the tailings were discussed. The solution test results show that Sporosarcina pasteurii could grow and reproduce rapidly in an acidic medium with an initial pH of 5. The uranium concentration decreased with the increase in MICP reaction time, and the removal efficiency reached 60.9% at 24 h. In the solidification test of tailings, the strength of tailings improved significantly after 12 days of reinforcement, with an increase in the cohesion of tailings by 2.937 times and an increased internal friction angle of 8.393°. The peak stress value of solidified tailings at the surrounding pressure of 50 kPa increased by 1.87 times, and the uranium concentration in the discharge fluid decreased by 76.91% compared to the blank group. This study provides valuable insights and references for safely disposing of uranium tailings.

Experimental Study on the Effect of an Organic Matrix on Improving the Strength of Tailings Strengthened by MICP.

In order to improve the effect of microbial-induced calcium carbonate precipitation (MICP) in tailings reinforcement, sodium citrate, an organic matrix with good water solubility, was selected as the crystal form adjustment template for inducing calcium carbonate crystallization, and the reinforcements of tailings by MICP were conducted in several experiments. The effects of sodium citrate on the yield, crystal form, crystal appearance, and distribution of calcium carbonate were analyzed by MICP solution test; thus, the related results were obtained. These showed that the addition of a proper amount of organic matrix sodium citrate could result in an increment in the yield of calcium carbonate. The growth rate of calcium carbonate reached 22.6% under the optimum amount of sodium citrate, and the crystals of calcium carbonate were diverse and closely arranged. Based on this, the MICP reinforcement test of tailings was carried out under the action of the optimum amount of sodium citrate. The microscopic analysis using CT and other means showed that the calcium carbonate is distributed more uniformly in tailings, and the porosity of samples is significantly reduced by layered scanning analysis. The results of triaxial shear tests showed that adding organic matrix sodium citrate effectively increased the cohesion, internal friction angle, and peak stress of the reinforced tailings. It aims to provide a novel idea, a creative approach, and a method to enhance the reinforcement effect of tailings and green solidification technology in the mining environment.

Effect of microbial-induced calcite precipitation on shear strength of gold mine tailings

Effect of microbial-induced calcite precipitation on shear strength of gold mine tailings