Tailings Content Research Articles

Effect of Copper Tailing Content on Corrosion Resistance of Steel Reinforcement in a Salt Lake Environment.

With the increasing proportions of copper tailings of concrete in the Qinghai Salt Lake area of China, there arises the problem of corrosion of steel reinforcement in concrete structures. In this study, we determine the corrosion rate (CR), crack width, and corrosion potential of the steel reinforcement with copper tailing. This was achieved by conducting the constant-current accelerated corrosion test with different proportions of copper tailing in the brine environment of the Qinghai province. The results demonstrate that the corrosion potential (Ecorr) and the passivation area of the polarization curve decrease with the increase in the corrosion time, and the corrosion rate and crack width increase with the increase in the corrosion time. When the corrosion time is the same, the corrosion potential, crack width, and corrosion depth of the reinforcement decrease first and then increase with the increase in the copper tailing powder content. When the copper tailing powder content is 20%, the above parameters reach the minimum value. In the salt lake environment of Qinghai, China, the copper tailing powder content is recommended to be 20%.

Solidification/stabilization of gold mine tailings using calcium sulfoaluminate-belite cement

In this study, calcium sulfoaluminate-belite cement (CSAB) was used to stabilize gold mine tailings, which are challenging materials to effectively immobilize due to high heavy metal and sulfate content. The hydration of CSAB cement yields ettringite and monosulfate with good capability for immobilizing sulfates and oxyanions in their crystal structure, in addition to physical encapsulation/solidification in a cementitious matrix. Different mix designs of CSAB cement and mine tailings were prepared, and the samples were cured at room temperature. Mechanical strength and heavy metal leaching were analyzed after 7 days, 28 days, and 90 days of curing, and the phase composition (XRD), thermogravimetric analysis (TGA), and microstructure (FESEM) were also studied. All harmful elements (cationic and oxyanion elements) were effectively immobilized during 7 days of curing, and the heavy metal immobilization remained constant after longer curing, according to an environmental leaching test. High mechanical strength results and good sulfate immobilization were obtained with mine tailing content up to 50 w-% of total binder material. With higher mine tailing content (75 w-% and 90 w-%), the mechanical strength and immobilization ability substantially decreased.

Effect of the Content of Micro-Active Copper Tailing on the Strength and Pore Structure of Cementitious Materials.

This study investigates the effect of micr-oaggregate filling with copper tailing on the pore structure of cement paste containing copper tailing (CPCT). The particle size of the CPCT and the pore structure of CPCT were analyzed by laser particle size analysis and mercury instruction porosimetry (MIP). Results showed that at the early stage of curing time, with increasing copper tailing content, the compressive strength of cement mortar with copper tailing (CMCT) was lower, and the porosity and pore diameter of CPCT were higher and greater; with the extension of curing age, when the content of copper tailing was less than 30%, the compressive strength of CMCT and the porosity of CPCT changed slightly with the increase of the content of copper tailing. However, the maximum hole diameter of CPCT decreased gradually (a curing age between 7 d and 365 d under standard conditions). Scanning electron microscopy analysis showed that at the early stage of cement hydration in the CPCT, the copper tailing did not fill the pores in CPCT well, while in the later stage of cement hydration, the microaggregates of copper tailing filled the pores well and closely combined with the surrounding hydration products. In the later stage of cement hydration, the microaggregate filling of copper tailing was primarily responsible for the strength increase of the CMCT.

The investigation of effect of particle size distribution on flow behavior of paste tailings

Determining the rheological behaviors of the materials in paste technology is very important when transporting the paste. The flow properties of the paste material inside the pipe should be determined when pumping at long distances. In this study, the flow behavior of paste tailings, which consists of different pulp densities (pd), were studied to determine the effect of the particle size distribution of the tailings on surface paste disposal. In other words, the study examined the effect of the particle size distribution on the rheological behavior of the tailings. According to the study's results, tailings with a particle size smaller than 38 μm behaved like a paste up to 70% pd. However, it lost its paste properties when the pd value increased. In the original tailings sample (as-received), half of the particles were under 38 μm, the behavior of the paste materials was observed up to 80% pd. In addition, in order to be pumped the paste, it was determined that the amount of <38 μm tailings content in the material had to be 20%. Furthermore, the methods are presented in this study for control the effect of the change in particle size distribution on the pumpability of the paste material.

Mine Tailings Geopolymers as a Waste Management Solution for A More Sustainable Habitat

The demand for low environmental impact of materials in our habitat is one of the current societal challenges. Along with other solutions of waste valorisation, alkali activation as geopolymers can be one possible solution of waste valorisation because they may allow, for instance, an alternative solution for cement-based materials in some applications and it is one contribution for circular economy. This work has focused on the development and processing of geopolymers that incorporates as a fine aggregate a high-sulfidic mining waste (mine tailing), a difficult waste to process. Rheology analysis was applied as an important step to understand not only the geopolymers behaviour but also its transition from the fresh to the hardened state. The effect of precursor binder type (metakaolin or blast furnace slag), of mine tailing content and also the effect of temperature and curing conditions of different formulations were studied in this solution. It was possible to conclude that although this particular mine tailing is not a geopolymer binder precursor, it may be incorporated as an alternative fine aggregate in construction products. Furthermore, rheology could be used to follow up the geopolymer alkali-activation process and even to setup proper curing conditions and components contents in order to optimize the final mechanical strength of this material as a waste management solution. The final properties of these geopolymers compositions were adequate and after 28 days of curing, these geopolymers exhibit significant chemical resistance under severe test conditions.

Reliability Assessment of Bearing Capacity of Cement–Iron Ore Tailing Blend Black Cotton Soil for Strip Foundations

A reliability estimate of bearing capacity values of cement–iron ore tailing treated black cotton soil was evaluated using a predictive model developed from laboratory results for specimens compacted at British Standard light, West African standard and British Standard heavy energy levels. Laboratory based geotechnical properties of the treated black cotton soil were incorporated into FORTRAN-based first-order reliability program to determine the reliability index values for the following parameters: cement content, C, Iron ore tailing content, IOT, cohesion, CO, friction angle, FA, percentage fine, PF, plasticity index, PI and unit weight, UW. Although cohesion, friction angle, plasticity index and unit weight were greatly influenced by the coefficient of variation, cement content C, IOT content IOT and percentage fine PF did not significantly affect the reliability index values. F-distribution test at 95% level of significance shows that compactive effort had significant effect on the outcome of the reliability index values. However, since reliability index (β) value of 1.0, which is considered adequate for serviceability limit state design, was not met, none of the compactive efforts could be used to model the behaviour of bearing capacity of cement–IOT treated black cotton soil. Hence, a more potent admixture should be used for improving the bearing capacity of strip foundation.

Mechanical and Electrical Characteristics of Graphite Tailing Concrete

The graphite tailing causes serious environmental pollution, and the pollution problem becomes worse and worse with the increase in graphite demands. This paper focuses on the graphite tailing concrete, which can alleviate the environment problem through utilizing graphite tailings. With the orthogonal experimental design, 16 groups of specimens were designed to investigate the compressive strength of the graphite tailing concrete, and each group had 6 specimens. The significance sequence of the influencing factors for the compressive strength was studied, including the ratio of water to cement, sand ratio, graphite tailings content, and carbon fiber content. The optimal contents of graphite tailings and carbon fiber were obtained from the further experimental study on the electrical characteristics of the graphite tailing concrete, and a regression analysis was conducted to develop the predictive mixture design relationships for the electrical resistivity of the conductive graphite tailing concrete. The experimental results show that the conductive concrete mixture containing graphite tailings and carbon fiber has satisfactory mechanical strength along with well electrical conductivity. With the increase in graphite tailings content, the compressive strength decreases slowly, but the electrical resistivity decreases much more obviously. Predictions with the proposed relationship are in reasonable agreement with experimental results. This study provides references for the graphite tailing utilization alleviating the environment problems.

Mechanical and hydration characteristics of autoclaved aerated concrete (AAC) containing iron-tailings: Effect of content and fineness

With the objective of reducing the negative impacts on environment and utilizing the secondary resource of tailings, the possibility of preparing AAC by using iron tailing was investigated. The bulk density and compressive strength were determined to indicating the feasibility of preparing AAC blocks from iron tailing. The morphology (FESEM-EDX), mineral constituent (XRD), thermal characteristics (TG-DSC) and crystal characteristics (29Si-NMR) of hydration products of AAC samples were analyzed to demonstrate the hydration characteristics of AAC products containing iron tailings effected by iron tailing content and fineness. The results indicated that the increasing content of iron tailing has negative effect on the mechanical property of AAC, and the finer of iron tailings can effectively enhance strength of AAC blocks. The main minerals in AAC products are C-S-H gel, tobermorite, anhydrite, hydrogarnet, and some residual minerals including quartz and calcite accompanied by ferric oxide and white mica in minor quantities. The increasing content of iron tailing obviously reduces the amount of calcium silicate hydrates; meanwhile, the finer of iron tailing accelerated the decomposition of white mica during the autoclaving process and has slight negative effect on crystallinity of tobermorite. It was also suggested that Al and Mg ions in iron tailings got into the structure of tobermorite during the hydrothermal reaction. This study provided the theoretical foundation for the utilizing of iron tailings in AAC production.

Fabrication of foam glass from iron tailings

Foam glass was prepared which using iron tailings and waste glass with SiC powders as foaming agent. The influence of the foam temperature on the bulk density, porosity, water absorption and compressive strength was studied. The results show that foam glass with higher iron tailings content of 24.5wt% could be prepared at about 830°C for 30min. Some of the reactions inside the iron tailings are responsible for the foaming mechanisms. When the foam temperature was 830°C, the bulk density and flexural strength reached a minimum value of 0.224g/cm3 and 0.53MPa.

Experimental study on recycling dredged marine sediment and phosphate tailing to produce earth fill

ABSTRACTEnvironmental friendly earth fill was produced by recycling dredged marine sediment and phosphate tailing. The properties of the marine sediment and tailing were tested. Composite soil samples of different mix ratios were prepared. The optimum moisture contents, basic physical properties, compression characteristics, and shear strength characteristics under the optimum moisture contents were tested and analyzed. The results indicated that the optimum moisture content decreases with increasing phosphorus tailing content and that composite soil is preferable over both marine sediment and phosphate tailing because of its higher dry density, lower compressibility, and higher shear strength. When the phosphorus tailing content is in 50–65%, the dry density is maximized and the void ratio is minimized, indicating the best ratio. The coefficient of compressibility is in 0.07–0.12 MPa−1. When the phosphorus tailing content is 50%, the compression index and coefficient of compressibility are minimized, whereas cohesion is maximized. The internal friction angle increases with increasing phosphorus tailing content. The optimum phosphorus tailing content is 50%; at this phosphorus tailing content, the compacted composite soil can be reutilized as good earth fill. The results demonstrate the properties and optimal conditions of composite soil composed of mud and silty sand.

Reusing copper tailings in concrete: corrosion performance and socioeconomic implications for the Lefke-Xeros area of Cyprus

Copper mining and processing activities at an abandoned mine in the Lefke-Xeros area of Cyprus have created a huge environmental contamination problem in the locality. As an alternative mitigation and management measure, we reported in previous studies that these tailings could be used as a concrete making material. In this paper, results of an experimental investigation of the reinforcement corrosion performance and cost efficiency of 0.57 and 0.50 w/b ratio concrete containing copper tailings either as a cement replacement or an additive material are presented. The time to initiation of corrosion and half-cell potential (HCP) of reinforcements were measured. Actual corrosion status of extracted reinforcement bars was also verified by visual inspection. Results showed that while early corrosion initiation occurred in some samples containing tailings as a cement replacement material, delayed corrosion initiation was observed in all samples containing copper tailings as an additive. Although HCP values became slightly more electronegative as tailings content of samples increased, no substantial reinforcement corrosion was observed. Based on corrosion performance and cost efficiency analyses, utilization of 5% pre-wetted tailings either as a cement replacement or an additive material is the best tailings reuse approach. Increased tourism-related businesses associated with reduced pollution of the Lefke-Xeros coastal area would have a positive impact on the socioeconomic status of the community.

Dynamic Load Effects of PVA Tail Sand Cement Base Composite Materials

This paper studies that dynamic load affects mechanical properties of materials about composite tail ore different replacement rate, different PVA fiber volume content and different plate thickness. The phenomenon of the tests and results showed that:1) PVA tailings cement-based composite materials has low damage, strong integrity and strong energy dissipation under dynamic loading. 2) When the volume content is 2%, material resistance effect is best. 3) The study proves that 30 mm plate have good ductility and Size effect influence the material mechanics performance. 4) PVA tailings cement-based composite materials under dynamic loads ,as tailings content increases the performance indicators reduced. So the engineering applications recommended replacement rate of the tailings is 50%.

Utilization of iron ore tailings as fine aggregate in ultra-high performance concrete

Iron ore tailings are a common type of hazardous solid waste in China and have caused serious environmental problems, and the high cost of producing ultra-high performance concrete (UHPC) provides the motivation to look for low-priced raw materials. In this paper, the possibility of using iron ore tailings to replace natural aggregate to prepare UHPC under two different curing regimes was investigated. It was found that 100% replacement of natural aggregate by the tailings significantly decreased the workability and compressive strength of the material. However, when the replacement level was no more than 40%, for 90days standard cured specimens, the mechanical behavior of the tailings mixes was comparable to that of the control mix, and for specimens that were steam cured for 2days, the compressive strengths of the tailings mixes decreased by less than 11% while the flexural strengths increased by up to 8% compared to the control mix. In addition, pore structure analysis revealed a coarsening of micro-pore structure with an increase of the tailings content and a good correlation between the porosities and compressive strengths of the UHPC matrices, and microstructure image showed a possibly poor interfacial transition zone around some tailings particles.

Preparation and Mineral Phases of Fired Brick Utilizing Iron Tailings

Using iron tailings from northern Tangshan region of China as the main material, fly ash and clay as the accessories, fired bricks were prepared. The influences of iron tailings content, heating rate, firing temperature and holding time on water absorption and compressive strength of bricks were investigated. the phases of fired bricks was characterized by XRD. The most suitable conditions is as follows: the range of the iron tailings content is 80%~ 95%, no more than 8°C/min has little effect on the properties of fired bricks, the range of feasible calcined temperature could be adjusted in 1020 ~ 1050°C for 1.5~2h, which make the physical properties and durability of fired bricks accorded with Chinese Fired Common Bricks Standard (GB/T5101-2003). The main mineral phases mainly constituted the mechanical strength of fired product are hematite, quartz, anorthite and augite.

Experimental Investigation on Autoclaved Aerated Concrete Using Palladium-Platinum Tailings

In this paper, the low-silicon palladium-platinum tailing is used to produce autoclaved aerated concrete. The influences of water binder ratio, palladium-platinum tailing content, lime content and conditioning agents on the compressive strength of the autoclaved aerated concrete are investigated. Optimal raw material formulation and procedure are determined for the autoclaved aerated concrete. The compressive strength and frost resistance of autoclaved aerated concrete made by the optimal raw material formulation and procedure meet with the requirements of autoclaved aerated concretes of B06 grade, and its thermal conductivity, drying shrinkage reach the requirements of the relevant national standards of China.

Durability-related properties of mortar and concrete containing copper tailings as a cement replacement material

This paper reports the results of research investigating the impact of copper tailings on some durability properties of cement pastes, mortars and concretes. Four mixtures incorporating copper tailings at 0% to 15% cement substitution levels by mass were used. Minor reductions in sulfate resistance of mortars and improved performance against autoclave expansion of pastes were observed in mixtures containing copper tailings. Despite increased water absorption and total permeable voids in concrete samples containing copper tailings, sample compressive and tensile strengths comparable to those of the control specimens were obtained. Resistance to acid attack and chloride penetration improved as the copper tailings content of mixtures increased. Moreover, chloride penetration depths obtained from immersion tests suggest that because the rapid chloride permeability test is an indicator of sample conductivity rather than chloride permeability, it may not be appropriate for evaluating mixtures with high-conductivity copper tailings. The high conductivity of concretes containing copper tailings could potentially be utilised in the de-icing of roadways and electromagnetic shielding of electrical and electronic devices.

Cement mixtures containing copper tailings as an additive: durability properties

The effects of copper tailings as an additive, on some durability properties of cement mixtures were investigated. In each mixture, copper tailings addition levels by mass were 0%, 5% and 10%. Compared to the control samples, copper tailings blended pastes showed superior performance against autoclave expansion while insignificant decreases in sulfate resistance of mortars were observed. Copper tailings increased the water absorption and total permeable voids of concretes slightly. However, the compressive and flexural strengths of blended concretes were higher than those of the control samples. Similarly, improved resistance to acid attack and chloride penetration as the copper tailings content of concretes increased were also observed. Results further showed that the ASTM C 1202 rapid chloride permeability test may not be a valid indicator of chloride migration in mixtures containing conductive copper tailings. These results suggest that copper tailings can potentially enhance the durability properties of cement based materials.

Impacts of Gold Mill Tailings Dumps on Agriculture Lands and its Ecological Restoration at Kolar Gold Fields, India

Huge amount of mill tailings at Kolar Gold Fields are creating environmental problems. In this study, an attempt was made to assess the impacts of mill tailings on agriculture lands and to identify suitable species for its reclamation. For this, soils collected from different agriculture lands were mixed with tailings in different proportions and tomato (<i>L</i><i>y</i><i>copersicon esculentum</i>) was planted in soils and mixtures. For selection of suitable species, native species were planted only in tailings. Physico-chemical properties varied in soils, tailings and mixtures. pH and electrical conductivity of soils increased with an increase of tailings content. Nitrogen, phosphorous, potassium, magnesium in soil-tailings showed symptoms of deficiency in tomato plants except calcium and sulphur. Correlation among iron, manganese, zinc and copper indicated common source of their occurrence. These elements decreased with increase of pH and sand percentage, and increased with the increase of clay content. Iron, manganese, copper in tomato fruits were within the limit whereas zinc was observed toxic beyond 30% of mill tailings. Soil/tomato plant transfer coefficients distinguished the concentrations of micronutrients in tomato fruits and soil-tailings mixture. Growth status of native species revealed that Babool, Gulmohar, Neem and Eucalyptus are suitable for dump reclamation.

Utilization of Iron Tailings for High Strength Fired Brick

his paper studies the feasibility of preparation high strength fired bricks from iron tailings with addition of clay and coal gangue. The results indicated that the optimum conditions were found to be that the hematite tailings content were 35%–50%; the firing temperature was 1000 °C. Under these conditions, the mechanical strength, the water absorption and the bulk density of the fired bricks were 21.17–26.14 MPa, 14.55–15.47% and 1.648–1.629g/cm3, respectively, these were well conformed to standards MU20 of Chinese Fired Common Bricks Standard (GB/T5101-2003).The phase composition and microstructure of the fired specimen were characterized by XRD and SEM. The results showed that the major crystalline phases present in fired brick were quartz, albite, amphibole, hematite and muscovite, and glass phase encapsulated and cement the crystalline phases forming strong entirety which promoted the strength of bricks.

Study on the Optimum Moisture of Cement-Solidified Sea Silt Road Embankment Adding Phosphate Tailing

The effect of moisture content on the density and the strength of cement-solidified sea silt road embankment adding phosphate tailing was investigated. The optimum solidifying time was determined based on uniform experimental design method considering the factors of cement content and phosphate tailing content at 5 design levels. The different mix proportions were defined. Utilizing compaction test and unconfined compression strength test, referencing to the fluidity experiment of cement concrete, the optimum moisture content is studied on the basis of theories and tests. The influence factors about the optimum moisture content are discussed.