Industrial utilization of arsenic-containing gold dressing tailings as pellet prepared by straight grate process

The utilization of arsenic-containing gold dressing tailings is an urgent issue faced by gold production companies worldwide.The thermodynamic analysis results indicate that ferrous arsenate(FeAsO_(4)),pyrite(FeS_(2))and sodium cyanide(NaCN)in the arsenic-containing gold metallurgical tailings can be effectively removed using straight grate process,and the removal of pyrite and sodium cyanide is basically completed during the preheating stage,while the removal of ferrous arsenate requires the roasting stage.The pellets undergo a transformation from magnetite to hematite during the preheating process,and are solidified through micro-crystalline bonding and high-temperature recrystallization of hematite(Fe_(2)O_(3))during the roasting process.Ultimately,pellets with removal rates of 80.77% for arsenic,88.78% for sulfur,and 99.88% for cyanide are obtained,as well as the iron content is 61.1% and the compressive strength is 3071 N,meeting the requirements for blast furnace burden.This study provides an industrially feasible method for treating arsenic-containing gold smelting tailings,benefiting gold production enterprises.

The potential of arbuscular mycorrhizal fungi to conserve Kalappia celebica,an endangered endemic legume on gold mine tailings in Sulawesi,Indonesia

Kalapi(Kalappia celebica)is an endemic legume of Sulawesi and has been included in the endangered category since the early 1980s.Conservation of the species is possible through ex situ culture techniques.Arbuscular mycorrhizal fungi(AMF)can accelerate plant growth which in turn supports the conservation of endangered species.This study aimed to assess the efficacy of local AMF to accelerate the growth of kalapi and increase nutrient uptake in kalapi grown in gold mine tailing media.There were three AMF treatments,Glomus claroideum,Glomus coronatum,and a mixture of both,plus the control.Each treatment was replicated three times,each consisting of five plants.The results show that the highest AMF colony was obtained by kalapi seedlings inoculated with Glomus coronatum and the mixture of AMF.The range of mycorrhizae inoculation effect values was 59.7–71.3%.AMF inoculation increased growth and dry weight of 4-month-old seedlings compared to controls.Dry and total weights of kalapi inoculated with G.coronatum were significantly different from those inoculated with the AMF mixture.However,they are not significantly different from kalapi inoculated with G.claroideum.The results also show that AMF increased nitrogen and phosphorous uptake by the roots,as well as nitrogen,phosphorous,potassium,manganese and iron by the shoots.All AMF treatments decreased potassium uptake in the roots,except in kalapi inoculated with G.coronatum.The AMF mixture decreased iron contents the roots by 15%.AMF can be developed into biofertilizer to support the conservation of kalapi in tropical Indonesia.

Characterization of colloidal arsenic at two abandoned gold mine sites in Nova Scotia, Canada, using asymmetric flow-field flow fractionation-inductively coupled plasma mass spectrometry

Asymmetric flow-field flow fractionation-inductively-coupled plasma-mass spectrometry was used to determine whether colloidal arsenic（As） exists in soil pore water and soil extract samples at two arsenic-contaminated abandoned gold mines（Montague and Goldenville, Nova Scotia）. Colloidal arsenic was found in 12 out of the 80 collected samples（= 15%）, and was primarily associated with iron（Fe） in the encountered colloids. The molar Fe/As ratios indicate that the colloids in some samples appeared to be discrete iron–arsenic minerals, whereas in other samples, they were more consistent with As-rich iron（oxy）hydroxides. Up to three discrete size fractions of colloidal As were encountered in the samples, with mean colloid diameters between 6 and 14 nm. The pore water samples only contained one size fraction of As-bearing colloids（around 6 nm diameter）, while larger As-bearing colloids were only encountered in soil extracts.

Influencing factors and optimization on mechanical performance of solid waste-derived rapid repair mortar

There is a great demand for high performance rapid repair mortar(RRM)because of the wide use of cement concrete.Solid-waste-based sulfoaluminate cement(WSAC)is very suitable as a green cementitious material for repair materials because of its characteristics of high early-age strength and short setting time.However,the influence and optimization of various factors of WSAC-based RRM,such as water-to-RRM ratio,binder-to-sand ratio and additives,as well as the further solid waste replacement of aggregate,remain to be studied.This paper comprehensively studied the influence of the above factors on the performance of WSAC-based RRM and obtained a green high-performance RRM by optimizing these factors.The experimental results showed that the early and late strength of the obtained RRM is excellent,and the setting time and fluidity are appropriate,which reflected good mechanical properties and construction performance.Ordinary Portland cement(OPC)doping could not improve RRM strength.It was feasible to prepare RRM with gold tailing sand replacing part of the quartz sand.This paper provides data and a theoretical basis for the preparation of high-performance RRM based on solid waste,expanding the high value utilization of solid waste,which is conducive to the development of a low carbon society.