外文翻译---钾明矾作为抑制剂从稀土精矿中选择性回收氟碳铈矿和独居石.docx

附录aselective flotation of bastnaesite from monazite in rare earth concentrates using potassium alum as depressantjun ren a, shaoxian song b, alejandro lopez-valdivieso b,shou ci lu cacenter of research on surfaces and interfaces, nanjing uniersity, nanjing 210093, chinabinstituto de metalurgia, uniersidad autonoma de san luis potosi, sierra leona 550, lomas 2a seccion, san luis potosi, c.p. 78210, s.l.p., mexicocresources engineering school, uniersity of science and technology beijing, 40 xueyuan road, beijing100083,china.abstractflotation studies were carried out on single particles of bastnaesite andmonazite to develop a flotation scheme for selectively removing monazite in the rare earth bulkconcentrate from the baiyunebo mine, in china 60.7% rare earth oxides or reo, 75% as bastnaesite and 25% as monazite . low additions of potassium alum were found to efficiently depress monazite at ph 5 without affecting the flotability of bastnaesite with the collector benzoic acid. the bulk concentrate was treated through this scheme, and 85% of the bastnaesite was recovered in a concentrate that assayed 69.5% reo and contained 97% bastnaesite. the depressing effect of potassium alum appeared to be due to the preferential adsorption of hydrolyzed aluminum species on monazite in comparison to bastnaesite.keywords: bastnaesite flotation; monazite flotation; rare earth mineral separation; alum as depressant;hydrolyzed aluminum ions.1. introduction1. introductionbastnaesite theoretically contains about 75% combined rare earth oxides reo andonly minor amounts of yttrium. flotation concentrates of bastnaesite usually containing. 60% reo can be upgraded to 70% reo by acid leaching to remove calcite and to 85%by a combination of acid leaching and calcining, which removes carbon dioxide from the carbonate. monazite theoretically can contain 70% reo including about 2% yttrium oxide, but most concentrates contain about 5565% reo. of the two minerals,bastnaesite is referred as the principal source of reo because it has high percentages of the light rare earth elements or the cerium group, namely elements having atomic numbers 57 through 63. monazite is recovered as a byproduct, needed to be stockpiled when produced in excess . the commercial bastnaesite deposit in mountain pass, california, usa is processedby flotation using a mixture of tall oil and lignin sulfonate at elevated temperature to selectively float bastnaesite .the main deposit of rare earth minerals located in the baiyunebo mine, in china represents 80% of the total reo world reserves falconnet,1985 . here, bastnaesite occurs together with monazite and they are both recovered inthe form of a bulk concentrate as a byproduct of iron ore mining. currently, there is aneed for further treatment of the bulk concentrate since its hydrometallurgical processinginvolves high costs due to the high content of monazite. numerous investigations havebeen carried out pursuing a flotation scheme for selectively separating bastnaesite and monazite. gu and zhu 1988 reported on the flotation separation of bastnaesite and monazite using n-hydroxylphthalimade as collector. phthalic acid in a weakly acidic. slurry was used by zhang 1985 as a selective collector to produce a bastnaesite concentrate of 98% purity, but with only 38% recovery. other collectors have been also recommended, namely hydroxy-naphthlyl hydroxamic acid and n-hydroxyl ph-thalicimide ren, 1993; ren et al., 1997 . not only effective collectors, but also efficient depressants play an important role inthe flotation of rare earth minerals( pradip and fuerstenau, 1991 ). while searching for collectors to selectively float bastnaesite over monazite, investigations were also per-formed in our laboratory to find a depressant that could be used to achieve theseparation between the two minerals. of all the inorganic and organic depressants tested,potassium alum was found to be the most promising depressant.this paper shows the results on the applicability of potassium alum as a depressant inthe selective flotation of bastnaesite from monazite in a rare earth bulk concentrate using benzoic acid as a collector. in addition, the methodology used to establish the flotationscheme for the separation process through studies on flotability of single particles of both bastnaesite and monazite is presented. 2. experimentalthe mineral samples of bastnaesite and monazite used in this work were obtainedfrom the haoniuping mine and southern rare earth mine, in china, respectively.by sieving, 37100 mm size particles were obtained for flotation tests, and y37 mm size particles for zeta potential measurements. through this procedure, the purity of thebastnaesite and monazite samples were 96.5% and 95.0%, respectively.a bastnaesite and monazite bulk concentrate, assaying 60.7% total reo, 4.3% cao,4.0% f and 11.5% p o , from the baiyunebo mine, in china, was used as sample for 25flotation studies to separate bastnaesite and monazite. the concentrate, with 75.1% reoas bastnaesite and 24.9% reo as monazite, also contained 1.3% sio and 4.3% fe as 2martite. in order to determine the relative proportion of bastnaesite and monazite in thevarious flotation products, both the total reo content and the reo content of bastnaesite were assayed in the products.benzoic acid used in this work was prepared in our laboratory and found to have 90.2% purity. potassium alum (kal (so4)2.12h2o), hydrochloric acid, sodium hydrox-ide and octanol were all analytical grade reagents.3. results and discussions3.1. flotation of bastnaesite and monazitethe effect of ph on the flotability of single particles of both bastnaesite and monazite using benzoic acid as a collector in the presence and absence of potassium alum is shown in fig. 1. it can be noted that both minerals present flotability peaks about ph 5 in the absence of potassium alum. these results indicate that there is no selectivity between bastnaesite and monazite in the whole ph range studied if only the collector benzoic acid is used. however, with 300 mgrl potassium alum, monazite is strongly depressed, while the flotability of bastnaesite is affected only slightly. around ph 5, the flotability difference between the two minerals is over 60%. clearly, potassium alum seems to be an efficient selective depressant for the separation of bastnaesite and monazite.fig. 1. flotability of bastnaesite and monazite as a function of ph in the presence and absence of potassium alum(kal (so4)2.12h2o) with benzoic acid as collector.the effect of potassium alum addition on the flotability of both bastnaesite and monazite with benzoic acid at ph 5 is shown in fig. 2. these results indicate that a high dosage of potassium alum not only depressed monazite, but also bastnaesite. theflotability curve for monazite exhibits a steep slope in the low potassium alum addition。range, whereas that for bastnaesite decreases only slightly as increasing the depressant addition in the low range before it declined sharply. there is an optimum potassium alum addition for the best selectivity in the flotation separation of bastnaesite and monazite. from the results shown in figs. 1 and 2, it can be seen that potassium alum preferentially depresses monazite over bastnaesite in a narrow addition range at ph4.55.5.potassium alum dissociates into k+,al3+,so2- ions and hydrolyzed aluminum species upon dissolution in water. in order to clarify which ions are responsible for thedepressing effect on monazite and bastnaesite, the effect of potassium sulfate k2so 4and aluminum sulfate al2（so4）3on the flotation of the two minerals were investigated separately. the results shown in fig. 3 indicate that aluminum sulfate depresses monazite and bastnaesite in the same manner as potassium alum, whereas potassiumsulfate does not have a significant influence on flotation. from these results, it can bereadily concluded that the depressing effect of potassium alum on monazite and bastnaesite was originated from aluminum ions and not from potassium or sulfate.however, there could be a combined effect of aluminum and sulfate ions, caused by the specific adsorption of sulfate ions .fig. 4 depicts a diagram showing the different species resulting from hydrolysis of aluminum ions for a 10-4 mol/l total concentration in aqueous solution . in this figure, it is shown that the aluminum-hydrolyzed species al(oh)2+and al (oh)2+ are predominant in the ph range（4.55.5）of depression of potassium alum. according to fuerstenau et al.these hydrolyzed species are strongly adsorbed onto polar surfaces, as those on bastnaesite and monazite.consequently, these surfaces increase their hydrophilicity. fig. 3. flotability of bastnaesite and monazite as a function of k2so 4 and al2（so4）3 addition with benzoic acid as collector at ph 5. fig. 4. species distribution diagram for10-4 mol/l total aluminum ions concentration （fuerstenau et al,1988 ）.the zeta potential of bastnaesite and monazite as a function of ph in the presence and absence of potassium alum is shown in fig. 5. the isoelectric point iep of bastnaesite and monazite in pure water occurs at ph 7.8 and 4.7, respectively. by adding 300 g/l potassium alum, the iep shifts to ph 8.1 and 6.9, respectively. this change on the iep is much greater for monazite than for bastnaesite. these results indicate that hydrolyzed aluminum species apparently are adsorbed, on a preferential basis, on monazite in comparison to bastnaesite. such preferential adsorption caused that potassium alum be an efficient depressant of monazite over bastnaesite during flotation.3.2. flotation of bastnaesite from bastnaesitemonazite bulk concentratethe foregoing concepts were tested as possible means for separating bastnaesite and monazite from the baiyunebo bastnaesitemonazite bulk concentrate. rougher flotation tests were carried out with slurries at 35% solid for 4 min. the results given in fig.6 show that without potassium alum, 70% of the monazite remained in the bastnaesite concentrate, indicating a very poor separation. as potassium alum addition is increased,then monazite was depressed below 10% recovery in the concentrate, without affectingfig. 5. zeta potential of bastnaesite and monazite as a function of ph in the presence and absence of potassium alum kal (so4)2.12h2o.bastnaesite recovery. accordingly, bastnaesite upgraded in the concentrate. the bulk concentrate was then treated using the flowsheet given in fig. 7. a 35%solid slurry was conditioned with 4 kg/ton potassium alum, 1.55 kg/ton benzoic acid,150 gr/on octanol at ph 5. rougher flotation was carried out for 4 min to obtain afig. 6. flotation recovery of bastnaesite and monazite from the baiyunebo bulk concentrate as a function of potassium alum kal (so4)2.12h2o addition with 1.55 kg/t on benzoic acid as collector at ph 5. the bastnaesite content in the flotation concentrate is also presented.fig. 7. schematic of the flowsheet for processing the baiyunebo bulk concentrate to selectively float bastnaesite from monazite. mass balance, reo grade, mineral recovery and mineral content are presented. concentrate that was cleaned twice without reagents for 2 min.through this methodol-ogy, a final bastnaesite concentrate assaying 69.5% reo with 97% bastnaesite at 85%bastnaesite recovery was obtained. the rougher flotation tailings is monazite concen-trate, which assayed 55% reo with 96% monazite. the recovery of monazite was 41%.the separation results are detailed in fig. 7. if the middling and the rougher flotation tailings were combined, the monazite concentrate would have assayed 48.6% reo with64.8% monazite and 92.4% monazite recovery. this product may be further treated to improve its reo grade by removing silica and martite. as can be noted, flotation with potassium alum as depressant and benzoic acid as collector yields satisfactory results for the separation of bastnaesite and monazite.4. summarya flotation scheme has been presented for separating bastnaesite and monazite using potassium alum as depressant and benzoic acid as collector in weakly acidic slurries.the process was tested on a bastnaesite and monazite bulk concentrate from the baiyunebo mine, in china (60.7% reo, 75% as bastnaesite and 25% as monazite) .from this process, a bastnaesite concentrate was produced assaying 69.5% reo with 97.2% bastnaesite. the recovery of bastnaesite was 84.7%. the depressing effect of potassium alum in the flotation separation of bastnaesite and monazite appeared to be due to the preferential adsorption of hydrolyzed aluminum ions on monazite in compari-son to bastnaesite.references(1)adamson, a.w., 1990. physical chemistry of surfaces, 5th edn. wiley, new york.falconnet, p., 1985. economics of rare earths. j. less-common met. 111, 915.(2)fuerstenau, d.w., khan, l.a., raghavan, s., pradip, 1983. alternate reagent scheme for the flotation ofmountain pass rare-earth ore. preprint xiv international mineral processing congress, toronto, cim,pp. 112.(3)fuerstenau, d.w., pradip, 1984. mineral flotation with hydroxamate collectors. reagents in the mineralsindustry, rome, imm, pp. 161168.4)fuerstenau, m.c., lopez-valdivieso, a., fuerstenau, d.w., 1988. role of hydrolyzed cations in the naturalhydrophobicity of talc. int. j. miner. process. 23, 161170.(5)gu, y., zhu, y., 1988. determination of protonation constant of f802 n-hydroxyphthalimade and stability constants of ionic complex compound of f802 with la iii . rare met. 7, 8186, in chinese .(6)hedrick, j.b., 1985. rare-earth elements and yttrium. in: horton, r.c. ed. ,mineral facts and problems,1985 edn. us department of the interior, washington, dc, pp. 647656.钾明矾作为抑制剂从稀土精矿中选择性回收氟碳铈矿和独居石摘要： 通过实验进行了对粒度嵌布较细的氟碳铈矿和独居石的实验研究，以制定一项浮选方案选择性去除稀土精矿中的独居石从中国白云鄂博矿（60.7稀土氧化物，75的氟碳铈矿和25的独居石）。发现在ph 为5时可以抑制独居石，而不会影响与苯甲酸作用的氟碳铈矿的可浮性。混合精矿通过这一方案，在稀土精矿品位为69.5时可以得到97%的氟碳铈矿且收率为85。钾明矾的抑制效果是水解铝离子优先吸附于独居石相比于氟碳铈矿。关键词：氟碳铈矿浮选；独居石浮选；稀土矿分离；钾明矾作为抑制剂；铝离子的水解。1绪论： 氟碳铈矿理论上大约75包含在稀土氧化物中且只含有少量钇。氟碳铈矿浮选精矿（通常包含60的稀土）可提高品位至70由稀土氧化物通过浸出除去方解石和通过酸浸和焙烧提高品位至85。独居石理论上可以70分布于稀土氧化物中，其中约2钇氧化物，但大多数精矿包含约5565的reo。在这两种矿物质中，氟碳铈矿被称为reo的主要来源，因为它具有较高的百分比。独居石是作为副产品回收，需要储存当产生过剩时。美国加利福尼亚氟碳铈矿矿床处理通过浮选使用一种高油和木质素磺酸盐的混合物选择性浮选氟碳铈矿，稀土矿床主要位于白云鄂博矿，在中国80的稀土矿物都分布在这，在这里，氟碳铈矿与独居石共生在一起，它们都通过大部分精矿的形式，作为铁矿石开采的副产品被回收。目前，有需要进一步处理那些大部分集中作为副产品的矿物，湿法冶金由于高昂的费用得到的独居石含量较高。许多实验研究都寻求了浮选的方法进行对氟碳铈矿独居石的分离。顾和朱1988报告了氟碳铈矿和独居石的浮选分离以n - hydroxylphthalimade作为捕收剂。张使用邻苯二甲酸在弱酸性矿浆中作为一种选择性的捕收剂使氟碳铈矿品位达到了98，但只有38回收率。其他捕收剂也已建议使用，即羟基naphthlyl羟肟酸和n -羟基ph thalicimide。不仅捕收剂，还有抑制剂都发挥重要作用在稀土矿物浮选。（普拉迪普和菲尔斯特瑙，1991年）。寻找捕收剂有选择地分离独居石和氟碳铈矿，试验还在我们的实验室进行，以找到一个较好的抑制剂来实现抑制分离两种矿物。在所有的无机和有机抑制剂测试中发现钾明矾是效果最好的抑制剂。 本文阐述了使用钾明矾作为抑制剂，苯甲酸作为捕收剂选择性从稀土混合精矿中浮选分离氟碳铈矿和独居石。此外，该方法通过可浮性分离过程的研究建立对单一颗粒氟碳铈矿和独居石浮选方案。2实验 在这项工作中使用的氟碳铈矿和独居石的矿物样品是出自haoniuping矿和南部稀土矿，矿样品先粉碎，通过筛选，37100毫米大小的粒子，进行浮选试验，小于37毫米的颗粒进行zeta电位测量。通过这一过程，该纯度氟碳铈矿和独居石样品分别为96.5和95.0。 氟碳铈矿和独居石混合精矿，含量测定总reo60.7，4.3氧化钙， 4.0f和11.5p 2o5 。白云鄂博矿的样品研究氟碳铈矿和独居石的分离。稀土精矿中有75.1的氟碳铈矿和24.9的独居石，还含有1.3二氧化硅和4.3铁。为了确定在氟碳铈矿和独居石的相对比例各种浮选产品，无论是总的reo中氟碳铈矿的品位和reo中氟碳铈矿的品位都要进行检测。 苯甲酸在这项工作中使用的是在我们的实验室制备，有90.2的纯度。钾明矾，盐酸，羟基-ide和辛醇均为分析纯试剂。3结果和讨论 关于矿浆ph对氟碳铈矿和独居石两单颗粒可浮性的影响，在使用苯甲酸作为捕收剂和钾明矾作为抑制剂的影响，如图所示1。可以说，当矿物可浮性的ph值为5时，峰值前缺乏钾明矾。结果表明，如果只使用捕收剂，而没有对ph的研究，药剂对于氟碳铈矿和独居石是没有选择性的。然而，当加入300 mg/l钾明矾时，强烈抑制独居石，而对氟碳铈矿可浮性的影响很小。当ph值为5时，矿物可浮性两者之间的差额超过60。显然，钾明矾是一个有效分离的抑制剂。 图一 图二矿浆ph作为一个影响氟碳铈矿和独居石的可浮性的一个指标，在以苯甲酸作为捕收剂，在有无钠明矾条件下对浮选的影响。 在以苯甲酸作为捕收剂，矿浆ph在5的条件下，钠明矾对于氟碳铈矿和独居石的可浮性影响见图二。这些结果表明，在抑制剂钾明矾用量较大的情况