Using cemented paste backfill to tackle the phosphogypsum stockpile in China:A down-to-earth technology with new vitalities in pollutant retention and CO_(2) abatement

Phosphogypsum(PG),a hard-to-dissipate by-product of the phosphorus fertilizer production industry,places strain on the biogeochemical cycles and ecosystem functions of storage sites.This pervasive problem is already widespread worldwide and requires careful stewardship.In this study,we review the presence of potentially toxic elements(PTEs)in PG and describe their associations with soil properties,anthropogenic activities,and surrounding organisms.Then,we review different ex-/in-situ solutions for promoting the sustainable management of PG,with an emphasis on in-situ cemented paste backfill,which offers a cost-effective and highly scalable opportunity to advance the value-added recovery of PG.However,concerns related to the PTEs'retention capacity and long-term effectiveness limit the implementation of this strategy.Furthermore,given that the large-scale demand for ordinary Portland cement from this conventional option has resulted in significant CO_(2) emissions,the technology has recently undergone additional scrutiny to meet the climate mitigation ambition of the Paris Agreement and China's Carbon Neutrality Economy.Therefore,we discuss the ways by which we can integrate innovative strategies,including supplementary cementitious materials,alternative binder solutions,CO_(2) mineralization,CO_(2) curing,and optimization of the supply chain for the profitability and sustainability of PG remediation.However,to maximize the co-benefits in environmental,social,and economic,future research must bridge the gap between the feasibility of expanding these advanced pathways and the multidisciplinary needs.

Particle aggregation and breakage kinetics in cemented paste backfill

The macroscopic flow behavior and rheological properties of cemented paste backfill(CPB)are highly impacted by the inherent structure of the paste matrix.In this study,the effects of shear-induced forces and proportioning parameters on the microstructure of fresh CPB were studied.The size evolution and distribution of floc/agglomerate/particles of paste were monitored by focused beam reflection measuring(FBRM)technique,and the influencing factors of aggregation and breakage kinetics of CPB were discussed.The results indicate that influenced by both internal and external factors,the paste kinetics evolution covers the dynamic phase and the stable phase.Increasing the mass content or the cement-tailings ratio can accelerate aggregation kinetics,which is advantageous for the rise of average floc size.Besides,the admixture and high shear can improve breaking kinetics,which is beneficial to reduce the average floc size.The chord length resembles a normal distribution somewhat,with a peak value of approximate 20μm.The particle disaggregation con-stant(k_(2))is positively correlated with the agitation rate,and k_(2) is five orders of magnitude greater than the particle aggregation constant(k1).The kinetics model depicts the evolution law of particles over time quantitatively and provides a theoretical foundation for the micromechanics of complicated rheological behavior of paste.

Recycling arsenic-containing bio-leaching residue after thermal treatment in cemented paste backfill:Structure modification,binder properties and environmental assessment

The substantial arsenic(As)content present in arsenic-containing bio-leaching residue(ABR)presents noteworthy environ-mental challenges attributable to its inherent instability and susceptibility to leaching.Given its elevated calcium sulfate content,ABR exhibits considerable promise for industrial applications.This study delved into the feasibility of utilizing ABR as a source of sulfates for producing super sulfated cement(SSC),offering an innovative binder for cemented paste backfill(CPB).Thermal treatment at varying temperatures of 150,350,600,and 800℃ was employed to modify ABR’s performance.The investigation encompassed the examination of phase transformations and alterations in the chemical composition of As within ABR.Subsequently,the hydration characteristics of SSC utilizing ABR,with or without thermal treatment,were studied,encompassing reaction kinetics,setting time,strength development,and microstructure.The findings revealed that thermal treatment changed the calcium sulfate structure in ABR,consequently impacting the resultant sample performance.Notably,calcination at 600℃ demonstrated optimal modification effects on both early and long-term strength attributes.This enhanced performance can be attributed to the augmented formation of reaction products and a densified micro-structure.Furthermore,the thermal treatment elicited modifications in the chemical As fractions within ABR,with limited impact on the As immobilization capacity of the prepared binders.

Effect of defatted flaxseed gum powder addition on the quality of sesame paste

The study explored the influence of defatted flaxseed gum powder(DFGP) on the stability and quality of sesame paste by measuring and analyzing its composition, color, texture, particle size, centrifugal oil separation rate,rheological properties, and microstructure. The results showed that the moisture and polysaccharide content of sesame paste was increased as the DFGP increased. Additionally, the hardness, gumminess, and chewiness of the sesame paste was improved, while the presence of particles with small particle size(1–100 μm) was decreased.The rate of oil precipitation was reduced by 28.99% when the amount of DFGP was 6%. The sesame paste samples exhibited pseudoplastic behavior, demonstrating shear thinning. As the shear rate increased, the apparent viscosity of sesame paste gradually decreased. Both the storage modulus(G’) and the loss modulus(G’’) increased as the shear frequency increased. The microstructure observation revealed that protein and oil were evenly distributed in the sesame paste system, and the addition of DFGP enhanced the bonding between oil and protein.This study can provide valuable references for high-quality sesame paste products in the food industry.

Contribution to the Study of Fungal Strains Contaminating Peanut Pastes in Bangui (Central African Republic)

Introduction: Peanut pastes are food products resulting from artisanal or industrial processing, used in cooking in Africa in general and in Central African Republic in particular. These peanut pastes are often contaminated by molds and filamentous fungi involved in the degradation of hygienic and organoleptic or even toxicological quality. This study aims to determine the epidemiological profile of molds contaminating peanut pastes sold on the Central African market. Methodology: This was a cross-sectional study carried out from June to September 2023. Samples of peanut pastes sold on Central African market were taken and analyzed at the National Laboratory of Clinical Biology and Public Health using the conventional microbiology method according to ISO 7954 standards. The data obtained were collected in the ODK 2023.3.1 application and analyzed with the Epi Info 7 software. A multivariate analysis by logistic regression, Ficher’s exact test, and chi2 at the 5% threshold (p Penicillium sp.;11.25% of Mucor sp.;10.63% of Aspergillus terrei;3.13% of Aspergillus niger;1.25% of Aspergillus medullans;28.13% of Aspergillus flavus;2.50% of Aspergillus fumigatus. Peanut pastes stored beyond three days were more contaminated (94.19%). Conclusion: The results of this study made it possible to highlight strains of mold that impact the hygienic and organoleptic quality of peanut pastes sold at the Central African market. Most of the isolated strains were the Aspergillus flavus species which is recognized by its toxigenic effects. This species is much more incriminated in the contamination of foodstuffs with the production of the toxin which causes underlying pulmonary pathologies in humans.

Mechanical properties and damage evolution characteristics of waste tire steel fiber-modified cemented paste backfill

During the process of constructional backfill mining,the cemented paste backfill(CPB)typically exhibits a high degree of brittleness and limited resistance to failure.In this study,the mechanical and damage evolution characteristics of waste tire steel fiber(WTSF)-modified CPB were studied through uniaxial compression tests,acoustic emission(AE)tests,and scanning electron microscopy(SEM).The results showed that the uniaxial compressive strength(UCS)decreased when the WTSF content was 0.5%,1%,and 1.5%.When the WTSF content reached 1%,the UCS of the modified CPB exhibited a minimal decrease(0.37 MPa)compared to that without WTSF.When the WTSF content was 0.5%,1%,and 1.5%,peak strain of the WTSF-modified CPB increased by 18%,31.33%,and 81.33%,while the elastic modulus decreased by 21.31%,26.21%,and 45.42%,respectively.The addition of WTSF enhances the activity of AE events in the modified CPB,resulting in a slower progression of the entire failure process.After the failure,the modified CPB retained a certain level of load-bearing capacity.Generally,the failure of the CPB was dominated by tensile cracks.After the addition of WTSF,a gradual increase in the proportion of tensile cracks was observed upon loading the modified CPB sample to the pore compaction stage.The three-dimensional localization of AE events showed that the WTSF-modified CPB underwent progressive damage during the loading,and the samples still showed good integrity after failure.Additionally,the response relationship between energy evolution and damage development of WTSF-modified CPB during uniaxial compression was analyzed,and the damage constitutive model of CPB samples with different WTSF contents was constructed.This study provides a theoretical basis for the enhancement of CPB modified by adding WTSF,serving as a valuable reference for the design of CPB constructional backfill.

Clinical Observation on the Treatment of Diabetic Kidney Disease with Damp-heat Stasis Syndrome in Clinical Proteinuria Stage by Kunkui Kidney Preserving Paste

[Objectives]To evaluate the clinical efficacy and safety of Kunkui Kidney Preserving Paste in the treatment of diabetic kidney disease(DKD)patients with damp-heat stasis syndrome in the clinical proteinuria stage.[Methods]Retrospective analysis was made on 30 patients with DKD who were diagnosed with damp-heat stasis syndrome in the clinical proteinuria stage from March 2021 to March 2023 in Jiangsu Province Hospital of Chinese Medicine,and who took Kunkui Kidney Preserving Paste continuously for six months.The urinary albumin/creatinine ratio(UACR),urinary complement C3,and urea nitrogen(BUN)of DKD patients before and after treatment were compared,and estimated glomerular filtration rate(eGFR),blood creatinine(Scr),and cystatin C(CysC)were estimated,and the therapeutic effects on renal function and urinary protein were evaluated.[Results]After treatment,UACR significantly decreased(P<0.01),and urinary complement C3 and Scr decreased(P<0.05),while other indicators showed no significant statistical difference(P>0.05).In terms of evaluating the efficacy of urinary protein therapy,8 cases showed recent relief;8 cases showed significant effect;9 cases were effective,and 5 cases were invalid after treatment,with a total effective rate of 83.33%.In terms of renal function efficacy evaluation,8 cases showed significant effect;4 cases were effective;11 cases were stable,and 7 cases were invalid,with a total effective rate of 76.67%.In the safety evaluation,there were no obvious adverse reactions.[Conclusions]The Kunkui Kidney Preserving Past has significant clinical efficacy and safety in treating DKD patients with damp-heat stasis syndrome in the clinical proteinuria period.It has significant advantages in reducing urinary protein and protecting renal function,which is worthy of clinical promotion.

Study on Quality Standards of Jianjin Zhuanggu Paste

[Objectives]Some Chinese medicinal materials of Jianjin Zhuanggu Paste were microscopically identified,and several active ingredients were studied by thin-layer identification,which provides reference for further improving the quality standards of hospital preparations.[Methods]The effective components of Jianjin Zhuanggu Paste were qualitatively identified by thin-layer chromatography(TLC).[Results]The microscopic identification of the three Chinese medicinal materials in Jianjin Zhuanggu Paste showed the microscopic characteristics of Radix Codonopsis,Radix Astragali and Radix Notoginseng.TLC identification showed that there were characteristic spots of Radix Codonopsis,Radix Astragali,Radix Rehmanniae Preparata and Radix Notoginseng in Jianjin Zhuanggu Paste.[Conclusions]This study established the quality standard research method of Jianjin Zhuanggu Paste,which further strengthens the safety standards of hospital preparations,and improves the clinical efficacy of drugs,as well as the quality standards of hospital preparations to a certain extent.

Yinqiao Sanhuang Paste Combined with Traditional Chinese Medicine Plaster for the Intervention of Drug Rash Induced by Targeted Therapy in Lung Cancer

Objective:To observe the efficacy and safety of Yinqiao Sanhuang Paste combined with traditional Chinese medicine plaster in treating drug rash caused by targeted therapy in lung cancer.Methods:A total of 100 lung cancer patients treated at our hospital from January 2021 to December 2023 were selected and randomly divided into an observation group and a control group,with 50 patients in each group.The control group received conventional medication,while the observation group was treated with Yinqiao Sanhuang Paste combined with traditional Chinese medicine plaster.The clinical symptom improvement and adverse reactions in both groups were observed.Results:The effective rate in the control group was 80.00%,while in the observation group,it was 96.00%,with a statistically significant difference between the two groups(P<0.05).The onset time,duration,and significant effect time in the control group were(2.41±0.29)days,(4.42±1.21)days,and(5.45±0.29)days,respectively;in the observation group,they were(2.44±0.21)days,(4.28±1.11)days,and(5.57±1.01)days,respectively.There was no statistically significant difference in the total onset time and total duration between the two groups(P>0.05).The incidence of adverse reactions in the control group was 28.00%,higher than the observation group’s 10.00%(P<0.05).Conclusion:Yinqiao Sanhuang Paste combined with traditional Chinese medicine plaster can effectively reduce the symptoms of drug rash induced by targeted therapy in lung cancer and lower the incidence of adverse reactions,indicating good clinical application value.

Atomization parameters of coal water paste measured by PIV technique

The particle image velocity (PIV) technique is introduced to measure theatomization angle, particle size and size distribution of the atomization coal water paste (CWP) ina cold state model. Due to high-density atomization spray, wide size distribution and large-scaleexperimental setup in CWP experiments, a commercial PIV system is updated with a 600-mm-long focallength camera and a convex lens used with a laser beam. This long focal length camera makes the PIVsystem capable of taking the images of micro particles. The measured minimum diameter is about 15μm. The convex lens has the benefit of centralising the sector laser beam of the PIV system, sothat the measurement window of the high density CWP field sectored by the laser beam is brighter andthe images taken by the camera are clearer. The experimental results show that it is a useful andefficient tool for the PIV technique to measure the atomization prosperities of CWP.

Caustics study of the effect of glass fibres on dynamic fracture of hardened cement paste

The reflected optical caustics method is applied to study dynamic fracture problems in hardened cement paste. First both the unreinforced cement paste and the glass fibres reinforced cement paste specimens were fabricated and the reflective coating on the surface of the specimen was prepared. Secondly the crack path and the shadow spot patterns during the crack propagation process for the two specimens were recorded by using a multi-spark high speed camera.Thirdly some dynamic parameters of two cement paste specimens including crack onset time the dynamic stress intensity factor and crack growth velocity were determined and analyzed comparatively.This indicates that the glass fibres can improve the fracture resistance and delay fracture time.These results will play an important role in evaluating the dynamic fracture properties of cement paste.

Determination of trace amount of antimony (Ⅲ) by adsorption voltammetry on carbon paste electrode

A sensitive method is described for the determination of trace antimony based on the antimony-bromopyrogallol red (BPR) adsorption at a carbon paste electrode (CPE). Three steps were involved in the overall analysis: preconcentration,reduction and stripping. Optimal conditions were found to be an electrode containing 25% paraffin oil and 75% high purity graphite powder as working electrode;a 0.10 mol/L HCl solution containing 40 μmol/L BPR as accumulation medium;a 0.20 mol/L HCl solution as reduction and stripping electrolyte;accumulation time,150 s;reduction potential and time,-0.50 V,60 s;scan range from -0.50 to 0.20 V. Interferences by other ions were studied as well. The detection limit was found to be 0.5 nmol/L for 150 s preconcentration. The linear range was from 1.0 nmol/L to 0.50 μmol/L. Application of the proposed method to the determination of antimony in water and human hair samples gave good results.

Study on Extraction Process of Phytoene from Tomato Paste

With tomato paste as raw material, the optimal extraction process of phy- toene from tomato paste was explored by orthogonal experiment on the basis of single-factor experiments. The results showed that the optimal extraction process for phytoene from tomato paste was as follows： extractant, acetone; solid to liquid ratio, 10：1; extraction time, 40 min; extraction temperature, 45 ℃. The developed extrac- tion process was stable, reasonable and feasible. Under the optimal extraction pro- cess, the extraction rate of phytoene reached 0.044 4%.

ADJUSTING EFFECTS OF APPLICATION OF GARLIC PASTE AT SHNQU (神阙 CV8) ON THE CIRCADIAN RHYTHM OF BODY TEMPERATURE INDUCED BY SLEEP DEPRIVATION

Objective To observe the effect of application of garlic paste at Shenque （神阙 CV8） on the circadian rhythm in sleep deprivation young students. Metheds Twenty healthy volunteer young male students from Southern Medical University were randomly divided into three groups： normal group （A）, sleep deprivation group （B） and treatment group （C）. Volunteers in group B and C received 48 h sleep deprivation （SD）, and in the mean time volunteers in group C were treated by garlic paste at Shenque （神阙 CV8）, while those in group A had no any treatment. The body temperature of all the volunteers was detected at 6：00 am, 12：00 am, 6：00 pm and 0：00 am, respectively, after the treatment. Results The mean body temperature values in group A and C both were highest at 6： 00 pm and lowest at 6： 00 am which had a significant difference in each group （P〈0.01）; in group B, the mean body temperature was highest at 0：00 am and lowestat 6：00 am, no significant difference was found between them （P〉0.05）. Results of cosine analysis showed that in subjects of group B the circadian rhythm of body temperature still kept going well after SD, but the peak amplitude and amplitude of vibration were higher than those of group A, and the acrophase of group B was obviously lower than that of group C and A. The 3 indexes of group C were similar to those of group A, denoting that garlic paste application of Shenque （神阙 CV8） could prevent disorders of circadian rhythm of the body temperature. Conclusion The garlic paste application at Shenque （神阙 CV8） can adjust circadian rhythm and accelerate the recovery processes of circadian rhythm in SD young students.

Effect of particle gradation characteristics on yield stress of cemented paste backfill

Along with slurry concentration and particle density,particle size distribution(PSD)of tailings also exerts a significant influence on the yield stress of cemented paste,a non-Newtonian fluid.In this work,a paste stability coefficient(PSC)was proposed to characterize paste gradation and better reveal its connection to yield stress.This coefficient was proved beneficial to the construction of a unified rheological model,applicable to different materials in different mines,so as to promote the application of rheology in the pipeline transportation of paste.From the results,yield stress showed an exponential growth with increasing PSC,which reflected the proportion of solid particle concentration to the packing density of granular media in a unit volume of slurry,and could represent the properties of both slurry and granular media.It was found that slurry of low PSC contained extensive pores,generally around 20μm,encouraging free flow of water,constituting a relatively low yield stress.In contrast,slurry of high PSC had a compact and quite stable honeycomb structure,with pore sizes generally<5μm,causing the paste to overcome a higher yield stress to flow.

基于Protel的Solder Masks与Paste Masks辨析

在不同的Protel 99 SE教材中,对于Solder Masks和Paste Masks的理解存在两种截然相反的意见,而且大多数教材对于Masks层没有给出详尽的解释,这些弊端都给初学者带来较大的困惑。通过对印制电路板掩膜层制造工艺的详细描述、单层显示演示以及Protel 99 SE帮助文件的诠注全面而充分地论证了Solder Masks和Paste Masks的实质含意。认为两者的实质是"阻焊膜与防锡膏膜",没有"互补关系"。

An analytical solution for evaluating the safety of an exposed face in a paste backfill stope incorporating the arching phenomenon

In current underground mining, the stability of the exposed backfill face is a basic issue associated with mining design and has been the subject of considerable research in mining safety and efficiency. In this study, an improved analytical solution for evaluating the safety of vertically exposed faces in backfilling was proposed. Based on a differential slice method, the proposed solution emphasizes the arching effect as having the advantages of more rigor and wider scalability. Feasibility of the proposed solution was validated with classic centrifuge results. Good agreement between compared results indicated that the proposed solution skillfully predicts the behavior of the paste centrifuge model. Additionally, calculation of exposed face safety in sequential filling was presented. The proposed solution has practical significance in mine backfill design.

Strength evolution and deformation behaviour of cemented paste backfill at early ages： Effect of curing stress, filling strategy and drainage

In this study, a pressure cell apparatus is developed to investigate the early age evolution of the strength and deformation behaviour of cemented paste backfill(CPB) when subjected to various loading conditions under different curing scenarios. The different curing scenarios that are simulated include:(1)drained and undrained conditions,(2) different filling rates,(3) different filling sequences, and(4) different curing stresses. The findings show that drainage, curing stress, curing time and filling rate influence the mechanical and deformation behaviours of CPB materials. The coupled effects of consolidation, drainage and suction contribute to the strength development of drained CPB subjected to curing stress. On the other hand, particle rearrangement caused by the applied pressure and suction development due to self-desiccation plays a significant role in the strength gain of undrained CPB cured under stress.Furthermore, curing stress induces slightly faster rate of cement hydration, which can contribute to strength acquisition.

Effect of Coal Gangue with Different Kaolin Contents on Compressive Strength and Pore Size of Blended Cement Paste

The effects of activated coal gangue on compressive strength, porosity and pore size distribution of hardened cement pastes were investigated. Activated coal gangue with two different kaolin contents, one higher and one lower, were used to partially replace Portland cement at 0%, 10%, and 30% by weight. The water to binder ratio（w/b） of 0.5 was used for all the blended cement paste mixes. Experimental results indicate that the blended cement of activated coal gangue mortar with higher kaolin mineral content has a higher compressive strength than that with lower kaolin mineral content. The porosity and pore size of blended cement mortar were significantly affected by the replacement of activated coal gangue.

Trace Determination of Scandium Using Adsorption Voltammetry of Mix-Polynuclear Complex of Scandium-Calcium-Alizarin Red S at Carbon Paste Electrode

A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the adsorbed complex were recorded by model JP-303 polarographic analyzer from 0.0 to -1.0 V (vs. SCE). The experimental conditions of the working procedure were optimized. The results show that the complex can be adsorbed on the surface of the CPE, yielding one peak at -0.61 V, corresponding to the reduction of the alizarin red S in the mix-polynuclear complex at the electrode. The detection limit of Sc^(3+) is 1.0×10^(-10) mol·L^(-1) for 3 min of accumulation time. The procedure was successfully applied to the determination of trace amount of scandium in the sample ores.