The use of Fenton＇s reagent （Fe^2＋/H2O2） and Fenton-like reagents containing transition metals of Cu（Ⅱ）, Zn（Ⅱ）, Co（Ⅱ）, and Mn（Ⅱ） for an alum sludge conditioning to improve its dewaterability was invest...The use of Fenton＇s reagent （Fe^2＋/H2O2） and Fenton-like reagents containing transition metals of Cu（Ⅱ）, Zn（Ⅱ）, Co（Ⅱ）, and Mn（Ⅱ） for an alum sludge conditioning to improve its dewaterability was investigated. The results obtained were compared with those obtained from conditioning the same alum sludge using cationic and anionic polymers. Experimental results show that Fenton＇s reagent was the best among the Fenton and Fenton-like reagents for the alum sludge conditioning. A considerable effectiveness of capillary suction time （CST） reduction efficiency of 47% can be achieved under test conditions of Fe^2＋/H2O2 = 20/125 mg/g DS （dry solid） and pH 6.0. The observation of floc-like particles after Fenton＇s reagent conditioning of alum sludge suggested that the mechanism of Fenton＇s reagent conditioning was different from that of polymer conditioning. In spite of the lower efficiency in the CST reduction of Fenton＇s reagent in alum sludge conditioning compared to that of polymer conditioning, Fenton＇s reagent offers a more environmentally safe option. Tiffs study provided an example of proactive treatment engineering, which is aimed at seeking a safe alternative to the use of polymers in sludge conditioning towards achieving a more sustainable sludge management strategy.展开更多
Froth flotation of scheelite has regained new focus since the 2010s and research regarding floatability and reagents has made great progress over the years. The main objective was and remains the selective flotation o...Froth flotation of scheelite has regained new focus since the 2010s and research regarding floatability and reagents has made great progress over the years. The main objective was and remains the selective flotation of scheelite from other calcium-bearing minerals, in particular calcite, fluorite and apatite. Due to similar properties, most attempts have limited success or only specific application(linked to a type of ore or a location). This article aims at reviewing all general physical-chemical information on froth flotation of scheelite, including electrokinetic properties, influence of p H and already existing reagents as well as ones still under examination. It appears that chelating or mixed collectors and modified versions of sodium silicate and quebracho hold great promise for scheelite flotation, while the use of said depressants and/or promoters seems inevitable.展开更多
Studies were carried out on the extraction characters of trivalent rare earths from chloride solutions using organophosphorus acids 2-ethylhexylphosphonic acid mono-（2-ethylhexyl） ester （HEHEHP） combined with [di-...Studies were carried out on the extraction characters of trivalent rare earths from chloride solutions using organophosphorus acids 2-ethylhexylphosphonic acid mono-（2-ethylhexyl） ester （HEHEHP） combined with [di-（2-ethylhexyl）-phosphoric acid （HDEHP）,isopropylphosphonic acid 1-hexyl-4-ethyloctyl ester （HHEOIPP）,bis（2,4,4-trimethylpentyl）-phosphinic acid （Cyanex 272）,bis（2,4,4-trimethypentyl）-monothiophosphinic acid （Cyanex 302） or bis（2,4,4-trimethypentyl）-dithiophosphinic acid （Cyanex 301）] as extractants. The effect of the equilibrium aqueous acidity on the extraction was studied. According to the corresponding separation factors for adjacent pairs of rare earths,it could be concluded that HEHEHP and Cyanex 272 could be employed for the separation of Tm（Ⅲ）,Yb（Ⅲ）,Lu（Ⅲ） from the other rare earths. Taking Yb（Ⅲ） as an example,based on the different stripping acid,the potential of the stripping was estimated.展开更多
Effects of size distribution (particle size and content of fine fraction (<10μm)) on scheelite flotation were studied using flotation tests and theoretical calculations. The results show that particle size influen...Effects of size distribution (particle size and content of fine fraction (<10μm)) on scheelite flotation were studied using flotation tests and theoretical calculations. The results show that particle size influences the scheelite recovery and the performance of combined reagents. The scheelite recovery is lowered by adding fine particles (<10μm) into the pulp containing coarse particles. Extended DLVO (EDLVO) theory confirms that the fine fractions (<10μm) could interface with the coarse fractions. The interaction energy and fluid forces are relative to the particle size, which might explain why the fine fractions influence the scheelite flotation. The highest recovery of scheelite using combined reagents as collector and optimum ratio of combined reagents were determined by scheelite particle size and reagent performance. However, the optimum adding order was only determined by reagent performance, which has nothing to do with particle size.展开更多
A complex lead-zinc-silver sulfide ore containing 2.98% Pb, 6.49% Zn and 116.32×10^-4 % Ag （mass fraction） from Yunnan Province, China, was subjected to this work. Research on mineral processing was conducted a...A complex lead-zinc-silver sulfide ore containing 2.98% Pb, 6.49% Zn and 116.32×10^-4 % Ag （mass fraction） from Yunnan Province, China, was subjected to this work. Research on mineral processing was conducted according to the properties of the lead-zinc-silver ore. Under low alkalinity condition, the lead minerals are successfully separated from the zinc minerals with new reagent YZN as zinc depressant, new reagent BPB as lead collector, CuSO4 as zinc activator and ethyl xanthate as zinc collector. The associated silver is mostly concentrated to the lead concentrate. With the process utilized in this work, a lead concentrate of 51.90% Pb with a recovery of 82.34% and a zinc concentrate of 56.96% Zn with a recovery of 81.98% are produced. The silver recovery in the lead concentrate is 80.61%. Interactions of flotation reagents with minerals were investigated, of which the results indicate that the presence of proper amount of Na2S can precipitate Pb^2＋ and has a sulfidation on oxidized lead minerals. The results also show that NazCO3 and YZN used together as combined depressants for sphalerite can signally improve the depressing effect of new reagent YZN on sphalerite.展开更多
Effects of carboxylic acid collector, benzohydroxamic acid (BHA), sodium hexametaphosphate (SHAP), sodium silicate, and oxalic acid on scheelite flotation were studied through flotation tests, quantum chemical calcula...Effects of carboxylic acid collector, benzohydroxamic acid (BHA), sodium hexametaphosphate (SHAP), sodium silicate, and oxalic acid on scheelite flotation were studied through flotation tests, quantum chemical calculation, and flotation solution computational chemistry. In terms of the calculation results, the relationship between chemical reactions occurring on the scheelite surface and molecular structures of the reagents were analyzed. The results show that BHA and carboxylic acid collectors interact with scheelite in different forms and the recovery of scheelite using sodium oleate as collector declines successively from SHAP, sodium silicate, to oxalic acid. Moreover, it is found that the performance of depressant in scheelite flotation is directly related to the group electronegativity, indicating that the latter is a dominant factor that determines the former. These findings will be helpful to the academic research communities of scheelite flotation.展开更多
Ilmenite is an essential mineral for the extraction of titanium.Conventional physical separation methods have difficulty recovering fine ilmenite,and dressing plants have begun applying flotation to recover ilmenite.T...Ilmenite is an essential mineral for the extraction of titanium.Conventional physical separation methods have difficulty recovering fine ilmenite,and dressing plants have begun applying flotation to recover ilmenite.The interaction of reagent groups with Ti and Fe sites on the ilmenite surface dramatically influences the ilmenite flotation.However,the investigation on Fe sites has received more attention because the activity of Ti is lower than that of Fe.For the activators on ilmenite flotation,most are metal ions but typically lead ions.The metal ions of activators promote ilmenite flotation by increasing the active sites on the ilmenite surface.Combined reagents have a better selective separation of ilmenite than single reagents due to their synergistic effect.Combining the lead ion(Pb^(2+))and the benzyl hydroxamic acid(BHA)into a Pb-BHA complex has a marked effect on ilmenite flotation,which puts forward a new idea of developing combined reagents for ilmenite flotation.This review considers reagent types and action mechanisms in ilmenite flotation.On the basis of the analysis of previous research,a brief future outlook of reagent types and action mechanisms in ilmenite flotation is also proposed in this study.展开更多
基金The first author would like to appreciate Ministry of Higher Education, Missions Department, Egypt for the fi- nancial support granted through Channel Scheme Mission.
文摘The use of Fenton＇s reagent （Fe^2＋/H2O2） and Fenton-like reagents containing transition metals of Cu（Ⅱ）, Zn（Ⅱ）, Co（Ⅱ）, and Mn（Ⅱ） for an alum sludge conditioning to improve its dewaterability was investigated. The results obtained were compared with those obtained from conditioning the same alum sludge using cationic and anionic polymers. Experimental results show that Fenton＇s reagent was the best among the Fenton and Fenton-like reagents for the alum sludge conditioning. A considerable effectiveness of capillary suction time （CST） reduction efficiency of 47% can be achieved under test conditions of Fe^2＋/H2O2 = 20/125 mg/g DS （dry solid） and pH 6.0. The observation of floc-like particles after Fenton＇s reagent conditioning of alum sludge suggested that the mechanism of Fenton＇s reagent conditioning was different from that of polymer conditioning. In spite of the lower efficiency in the CST reduction of Fenton＇s reagent in alum sludge conditioning compared to that of polymer conditioning, Fenton＇s reagent offers a more environmentally safe option. Tiffs study provided an example of proactive treatment engineering, which is aimed at seeking a safe alternative to the use of polymers in sludge conditioning towards achieving a more sustainable sludge management strategy.
基金the financial support of the Optim Ore projectthe European Union’s Horizon 2020 research and innovation programme under grant agreement No. 642201
文摘Froth flotation of scheelite has regained new focus since the 2010s and research regarding floatability and reagents has made great progress over the years. The main objective was and remains the selective flotation of scheelite from other calcium-bearing minerals, in particular calcite, fluorite and apatite. Due to similar properties, most attempts have limited success or only specific application(linked to a type of ore or a location). This article aims at reviewing all general physical-chemical information on froth flotation of scheelite, including electrokinetic properties, influence of p H and already existing reagents as well as ones still under examination. It appears that chelating or mixed collectors and modified versions of sodium silicate and quebracho hold great promise for scheelite flotation, while the use of said depressants and/or promoters seems inevitable.
基金Project supported by the Science and Technology Research Project of Hubei Provincial Department of Education (B20094007)Wuhan Mu-nicipal Institutions of Scientific Project (2008K018)
文摘Studies were carried out on the extraction characters of trivalent rare earths from chloride solutions using organophosphorus acids 2-ethylhexylphosphonic acid mono-（2-ethylhexyl） ester （HEHEHP） combined with [di-（2-ethylhexyl）-phosphoric acid （HDEHP）,isopropylphosphonic acid 1-hexyl-4-ethyloctyl ester （HHEOIPP）,bis（2,4,4-trimethylpentyl）-phosphinic acid （Cyanex 272）,bis（2,4,4-trimethypentyl）-monothiophosphinic acid （Cyanex 302） or bis（2,4,4-trimethypentyl）-dithiophosphinic acid （Cyanex 301）] as extractants. The effect of the equilibrium aqueous acidity on the extraction was studied. According to the corresponding separation factors for adjacent pairs of rare earths,it could be concluded that HEHEHP and Cyanex 272 could be employed for the separation of Tm（Ⅲ）,Yb（Ⅲ）,Lu（Ⅲ） from the other rare earths. Taking Yb（Ⅲ） as an example,based on the different stripping acid,the potential of the stripping was estimated.
基金Project(51074037)supported by the National Natural Science Foundation of China
文摘Effects of size distribution (particle size and content of fine fraction (<10μm)) on scheelite flotation were studied using flotation tests and theoretical calculations. The results show that particle size influences the scheelite recovery and the performance of combined reagents. The scheelite recovery is lowered by adding fine particles (<10μm) into the pulp containing coarse particles. Extended DLVO (EDLVO) theory confirms that the fine fractions (<10μm) could interface with the coarse fractions. The interaction energy and fluid forces are relative to the particle size, which might explain why the fine fractions influence the scheelite flotation. The highest recovery of scheelite using combined reagents as collector and optimum ratio of combined reagents were determined by scheelite particle size and reagent performance. However, the optimum adding order was only determined by reagent performance, which has nothing to do with particle size.
基金Project(50874117) supported by the National Natural Science Foundation of China
文摘A complex lead-zinc-silver sulfide ore containing 2.98% Pb, 6.49% Zn and 116.32×10^-4 % Ag （mass fraction） from Yunnan Province, China, was subjected to this work. Research on mineral processing was conducted according to the properties of the lead-zinc-silver ore. Under low alkalinity condition, the lead minerals are successfully separated from the zinc minerals with new reagent YZN as zinc depressant, new reagent BPB as lead collector, CuSO4 as zinc activator and ethyl xanthate as zinc collector. The associated silver is mostly concentrated to the lead concentrate. With the process utilized in this work, a lead concentrate of 51.90% Pb with a recovery of 82.34% and a zinc concentrate of 56.96% Zn with a recovery of 81.98% are produced. The silver recovery in the lead concentrate is 80.61%. Interactions of flotation reagents with minerals were investigated, of which the results indicate that the presence of proper amount of Na2S can precipitate Pb^2＋ and has a sulfidation on oxidized lead minerals. The results also show that NazCO3 and YZN used together as combined depressants for sphalerite can signally improve the depressing effect of new reagent YZN on sphalerite.
基金financially supported by the National Natural Science Foundation of China(No.51074037)
文摘Effects of carboxylic acid collector, benzohydroxamic acid (BHA), sodium hexametaphosphate (SHAP), sodium silicate, and oxalic acid on scheelite flotation were studied through flotation tests, quantum chemical calculation, and flotation solution computational chemistry. In terms of the calculation results, the relationship between chemical reactions occurring on the scheelite surface and molecular structures of the reagents were analyzed. The results show that BHA and carboxylic acid collectors interact with scheelite in different forms and the recovery of scheelite using sodium oleate as collector declines successively from SHAP, sodium silicate, to oxalic acid. Moreover, it is found that the performance of depressant in scheelite flotation is directly related to the group electronegativity, indicating that the latter is a dominant factor that determines the former. These findings will be helpful to the academic research communities of scheelite flotation.
基金financially supported by the National Natural Science Foundation of China(No.51764022)the Fok Ying Tong Education Foundation(No.161046)+3 种基金the China Postdoctoral Science Foundation(No.2020M673551XB)the Fundamental Research Funds for Central UniversitiesChina(No.2020XJHH04)the Yueqi Outstanding Scholar Award of China University of Mining and Technology(Beijing)。
文摘Ilmenite is an essential mineral for the extraction of titanium.Conventional physical separation methods have difficulty recovering fine ilmenite,and dressing plants have begun applying flotation to recover ilmenite.The interaction of reagent groups with Ti and Fe sites on the ilmenite surface dramatically influences the ilmenite flotation.However,the investigation on Fe sites has received more attention because the activity of Ti is lower than that of Fe.For the activators on ilmenite flotation,most are metal ions but typically lead ions.The metal ions of activators promote ilmenite flotation by increasing the active sites on the ilmenite surface.Combined reagents have a better selective separation of ilmenite than single reagents due to their synergistic effect.Combining the lead ion(Pb^(2+))and the benzyl hydroxamic acid(BHA)into a Pb-BHA complex has a marked effect on ilmenite flotation,which puts forward a new idea of developing combined reagents for ilmenite flotation.This review considers reagent types and action mechanisms in ilmenite flotation.On the basis of the analysis of previous research,a brief future outlook of reagent types and action mechanisms in ilmenite flotation is also proposed in this study.
