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Low winter temperatures are a widespread concern for mines in China that use cemented paste backfill (CPB). A low environmental temperature has a significant effect on the CPB temperature, which can affect its hydration rate and early strength. Using paste material from the Jiashi Copper Mine (JCM) in winter, this paper prepared a total of 129 specimens and investigated the effect on these specimens of different amounts of water and cement, the method for adding cement, the dosage of the pumping agent, and the amount of aggregate used. The prepared specimens had a temperature range of 8-12℃ and were cured in a standard curing box with a temperature of 20℃ and humidity of 95%. After curing periods of 3, 7, and 28 d, the paper performed uniaxial compressive strength (UCS) tests on the specimens. The test results show that the UCS values of the 7 d and 28 d specimens are 1.44-fold and 2.4-fold those of the 3 d specimens, respectively. The 7 d UCS evolution accords with a 2℃ hydration progress, which leads to gradual strength development. However, the 28 d UCS evolution accords with a 20℃ hydration progress. This indicates that the temperature of the paste has a slight effect on its long-term strength. Based on the effect of low temperature on the strength of the 7 d paste, the paper proposed the addition of high-temperature water to the paste backfill system. Using a practical paste ratio at the JCM, the paper calculated a theoretical high-temperature water flow of 6-8 m3·h-1. When the water temperature ranges between 70-100℃, the temperature of the paste can be improved from 6℃ to 15-19℃. The paper recommends the use of an industrial water heater for providing the hot water, with a conservative power output of 400 kW. The use of this water heater will yield a cost improvement of 2.9 RMB per cube of filling material.

In mining, cement paste backfill technology uses the high concentration tailings that remain after mineral processing to backfill underground stopes. These tailings are prepared by dewatering, mixed with a proportion of cement or other binder, then, after sufficient mixing, the saturated homogenized slurry is pumped or gravity-transported. Therefore, high concentration tailings are a prerequisite for cement paste backfill preparation and high quality backfill. The paste thickener is a key component that shows high efficiency dewatering, and rake shearing greatly affects tailings dewatering performance; therefore, appropriate rake torque design is crucial for efficient paste thickener operation. Rake torque is a key factor in determining the dewatering extent and the rate of flocculation in the networked structure bed in the thickener compression zone. In some industry processes, the problems of rake bogging, rat holing, swirl motion, and insufficient underflow concentration can affect production or seriously damage equipment. All these problems can be attributed to poor rake design or operation. Based on the non-Newtonian characteristics of a mud bed and the correlation of slurry initial shear stress with solids concentration, a torque mathematical model was proposed. The model predicted a rake torque increase with an increase in underflow concentration during thickener operation; the percentage of rake torque variation reached 4.67%. Regression analysis indicates that the percentage of rake torque presents as a polynomial function of the underflow concentration. At the same time, bed height affected rake torque slightly and the rake torque percentage varied within 0.27% when the bed height fluctuated. The predicted effects of underflow concentration and bed height on rake torque are confirmed and compared with 64 h of operational data on thickener operations in a lead-zinc mine.

The sludge height and underflow rate are the two most important parameters for deep cone thickeners. Therefore, studying the law of change of the underflow concentration with sludge height is important. Discontinuous or continuous dynamic compaction processes of the tailings were investigated physically by using a small, self-made deep cone thickener. Using the power function relation between effective void ratio and mud pressure and combining with force analyses of the tailing particles, this study deduced a mathematical model of underflow concentration and sludge height. The results revealed the inner floc structure relation between underflow concentration and sludge height of the deep cone thickener. In addition, the law of change of this model was explained by applying a spatial structure theory of tailings particles. Based on the requirements for the underflow concentration of mine production, the mathematical model was applied, the reasonable range of sludge height was presented, and the reliability of this model was verified. Moreover, this mathematical model provides a theoretical basis for the design and operation of deep-cone thickeners.

The cemented backfill body with sulphide-containing tailings exhibits a swelling phenomenon with an extension of curing age. The test results from the uniaxial compressive strength test of the backfill specimen with an obvious fracture are very discrete, and the mechanical parameters of the filling body will not be obtained effectively. The fractured surface image of the backfill were binarized by the digital image processing technology. Additionally, its fractal dimension was calculated and analyzed. Then, the relationship between fractal dimension and uniaxial compressive strength was established. The results indicate that the cracks on the surface of the backfill specimen exhibite self-similarity. The fractal dimension increases with the development of surface cracks. There is a negative correlation between fractal dimension and uniaxial compressive strength for the sulphide-containing backfill. It is of practical significance to determine the research value of the compression test using the fractal dimension. When the fractal dimension of the surface cracks is less than a certain threshold, the results of the specimen strength tests would be reliable.

Paste made from high-sulfur tailings shows strength deterioration to different degrees and this can cause great changes in the quality of the filling body. The deterioration and degradation mechanism of high-sulfur paste with different sulfur contents was analyzed using XRD (X-ray diffraction) phase analysis and an ESEM. The results showed that sulfur tailings promoted the growth of early strength to a certain extent, but inhibited the development of later strength, and the greater the sulfur content, the more obvious the effect. In addition, sulfate produced by sulfide oxidation can promote the formation of expansive ettringite and gypsum. Meanwhile, the acidic environment caused decalcification of C-S-H and dissolution of CH, destroys the cementitious system and further promotes the degradation of the filling body. The crystal expansion strain and crack development process were analyzed using a pore calculation model. The linear development of elastic strain in swelling material was clarified.

The preparation of cementitious materials for filling primarily via the alkali-activated method was discussed to recycle copper slags. A mixture of lime, NaOH, and early-strength agent was selected as a composite activator to carry out copper slag activation and filling material-preparation experiments, and the hydration products were analyzed by X-ray diffraction and scanning electron microscopy. The test results show that the effect of different activators on sample strength follows the order lime > early-strength agent > NaOH. The strengths of slag paste samples at 7 and 28 d post-curing reach 1.5 and 3.0 MPa, respectively. The strength of filling materials mixed by copper slag and tailings is 1.0 MPa as the curing ages are 28 d, and the slurry has well fluidity. These values meet the requirements of a suitable filling material. The early hydration products of copper slag mainly include Ca(OH)2 and C-S-H gel. As the curing time increases, the Ca/Si ratio of the C-S-H gel decreases and the structure of the hydration products becomes more compact. After curing for 28 d, the active components in the copper slag are nearly completely reacted.

First, the quantitative characterization of cement paste backfilling (CPB) material characteristics was studied, and a comprehensive index called solid filling rate was presented to describe the interaction of material characteristics, through analyzing the substance composition of CPB microstructure. Then, rheological experiments were made to get the corresponding rheological curves, which were fitted by the Bingham model to get the yield stress and plastic viscosity of CPB. The influence of material characteristics such as volume fraction, weighted average grain diameter, nonuniform coefficient, the mass fraction of fine particles and cement on CPB rheological parameters was analyzed, and its mechanism was explained from the view of microstructure. At last, a calculation model of rheological parameters including solid filling rate was constructed. The results indicate that under the same conditions, the yield stress and plastic viscosity increase exponentially along with the increase of volume fraction, decrease with the increase of nonuniform coefficient, and decrease first and increase soon with the increase of fine particles.

It is a universal phenomenon for all the mines that paste-filling material arrives at stope at different initial temperatures. The strength properties and stress-strain relation of paste at different initial temperatures have effect on the mining-filling cycle and the dilution of adjacent stope mining. A series of uniaxial compressive strength tests were performed on hardened paste with initial temperatures of 2, 20, 35 and 50℃ to obtain the stress-strain evolution curves at different initial temperatures. The damage constitutive models of paste at different initial temperatures were established on the basis of theoretical derivation and experimental results. A temperature-time coupling damage constitutive model was further proposed according to parameter regression of the established models. Finally, the temperature-time coupling damage constitutive model was embed into the solid mechanics module of Comsol software, which is for uniaxial compressive experiment simulation. The simulation results show good accordance with the experimental stress-strain curves, verifying the reliability of the proposed constitutive model.

This article is focused on the leaching kinetic of copper oxide ore containing carbonate gangue.The effects of temperature,acid concentration,particle size,liquid-to-solid ratio and stirring rate on leaching of the copper oxide ore were determined.The results show that high temperature,high acid concentration,high liquid-to-solid ratio,low particle size and high stirring rate benefit the copper leaching.However,the carbonate gangue leads to a high consumption of acid.In consideration of leaching cost,the proper leaching condition is the temperature of 303 K,acid concentration of 35 g·L-1,particle size of 0.074-0.125 mm,liquid-to-solid ratio of 3:1,and stirring rate of 180 r·min-1.After leaching for 180 min,the copper leaching rate reaches 53.6%.The morphologies of the ore surface before and after leaching were investigated and the results reveal that the carbonate gangue dissolves in the acid solution and CaSO4·2H2O precipitation forms on the ore surface,which limits the development of porosity and cracks.Based on the shrinking core model,the leaching kinetic was analyzed.It is found that the precipitation on the ore surface hinders the leaching reaction.The diffusion across the product layer is the rate-controlling step and the activation energy is determined to be 8.65 kJ·mol-1.

This paper presents the fabrication technologies related to flexible titanium-dioxide (TiO2) working electrodes and graphite counter electrodes on plastic substrates for dye-sensitized solar cells (DSSCs). The DSSC on a plastic substrate had a sandwich structure consisting of a TiO2 working electrode, an electrolyte, and a graphite counter electrode. Nano-crystalline TiO2 powder, titanium (IV) bis (ammonium lactato) dihydroxide (TALH), de-ionized water (DI water), and Triton X-100 were added to the mixture of PDMS base and curing agents to form TiO2 colloids for the TiO2 working electrode. The material analysis of the TiO2 working electrode and the graphite counter electrode employed field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Nano-crystalline TiO2 powder was used to form the TiO2 working electrode. The surface characteristics of the TiO2 and graphite films were investigated herein. The low-cost fabrication technologies of the TiO2 working electrode and graphite counter electrode on the plastic substrate were clearly demonstrated.

Abstract Background Shuanglong formula (SLF), a Chinese medicine composed of panax ginseng and salvia miltiorrhiza exhibited significant effect in the treatment of myocardial infarction (MI) in clinical. Because of the complex nature and lack of stringent quality control, it's difficult to explain the action mechanism of SLF. Method In this study, we present a "system to system" (S2S) mode. Based on this mode, SLF was simplified successively through bioactivity-guided screening to achieve an optimized minimal phytochemical composition (new formula NSLF6) while maintaining its curative effect for MI. Results Pharmacological test combining with the study of systems biology show that NSLF6 has activity for treatment MI through synergistic therapeutic efficacies between total ginsenosides and total salvianolic acids via promoting cardiac cell regeneration and myocardial angiogenesis, antagonistic myocardial cell oxidative damage. Conclusions The present S2S mode may be an effective way for the discovery of new composite drugs from traditional medicines.

Abstract Background The association of rs17321515 single nucleotide polymorphism (SNP) near TRIB1 gene and serum lipid profiles has never been studied in the Chinese population. Therefore, the present study was undertaken to detect the association of rs17321515 SNP and several environmental factors on serum lipid levels in the Mulao and Han populations. Methods A total of 639 unrelated subjects of Mulao nationality and 644 participants of Han nationality were randomly selected from our previous stratified randomized cluster samples. Genotypes of the TRIB1 rs17321515 A>G SNP were determined via polymerase chain reaction and restriction fragment length polymorphism, and then confirmed by direct sequencing. Results Serum apolipoprotein (Apo) B levels were higher in Mulao than in Han (P < 0.05). There were no differences in the genotypic and allelic frequencies between the two ethnic groups (P > 0.05). High- and low-density lipoprotein cholesterol (HDL-C and LDL-C) levels in Han were different among the genotypes (P < 0.05 for each), the subjects with AG/GG genotypes had higher HDL-C and LDL-C levels than the subjects with AA genotype. Total cholesterol (TC), HDL-C, LDL-C, ApoA1 and ApoB levels in Han males were different among the genotypes (P < 0.05-0.001), the G carriers had higher TC, HDL-C, LDL-C, ApoA1 and ApoB levels than the G noncarriers. HDL-C levels in Mulao males were different among the genotypes (P < 0.05), the G carriers had lower HDL-C levels than the G noncarriers. Serum HDL-C and LDL-C levels in both ethnic groups and TG levels in Han were correlated with the genotypes or alleles (P < 0.05-0.01). TG and HDL-C levels in Mulao males and TG, HDL-C, LDL-C and ApoA1 levels in Han males were correlated with genotypes or alleles (P < 0.05-0.001). TG and ApoA1 levels in Han females were associated with genotypes (P < 0.05 for each). Serum lipid parameters were also associated with several environmental factors in both ethnic groups. Conclusions The associations of TRIB1 rs17321515 SNP and serum lipid levels are different between the Mulao and Han populations. These discrepancies might partly result from different TRIB1 gene-environmental interactions in both ethnic groups.

Abstract Background The aim of this study is to compare the cost-effectiveness of screening with stool DNA testing with that of screening with other tools (annual fecal occult blood testing, flexible sigmoidoscopy every 5 years, and colonoscopy every 10 years) or not screening at all. Methods We developed a Markov model to evaluate the above screening strategies in the general population 50 to 75 years of age in Taiwan. Sensitivity analyses were performed to assess the influence of various parameters on the cost-effectiveness of screening. A third-party payer perspective was adopted and the cost of $13,000 per life-year saved (which is roughly the per capita GNP of Taiwan in 2003) was chosen as the ceiling ratio for assessing whether the program is cost-effective. Results Stool DNA testing every three, five, and ten years can reduce colorectal cancer mortality by 22%, 15%, and 9%, respectively. The associated incremental costs were $9,794, $9,335, and $7,717, per life-year saved when compared with no screening. Stool DNA testing strategies were the least cost-effective with the cost per stool DNA test, referral rate with diagnostic colonoscopy, prevalence of large adenoma, and discount rate being the most influential parameters. Conclusion In countries with a low or intermediate incidence of colorectal cancer, stool DNA testing is less cost-effective than the other currently recommended strategies for population-based screening, particularly targeting at asymptomatic subjects.