Coordination leaching of tungsten from scheelite concentrate with phosphorus in nitric acid

A hydrometallurgical process for tungsten extraction and recovery from scheelite is reported.The technology includes leaching scheelite using phosphoric acid as chelating agent in nitric acid solutions,extracting tungsten by solvent extraction and reusing leaching agent.In the leaching process,affecting factors,such as temperature,leaching time,nitric acid and dosage of phosphoric acid,were examined on recovery of tungsten.Results show that more than 97%of tungsten could be extracted under conditions of leaching temperature of 80-90°C,HNO3 concentration of 3.0-4.0 mol/L,liquild-to-soild ratio of 10:1,H3PO4 dosage of 3 stoichiometric ratio and leaching time of 3 h.Solvent extraction was then employed for the W recovery from the leachate with a organic system of 40%(v/v)N235,30%(v/v)TBP,and 30%sulfonated kerosene.Approximately 99.93%of W was extracted and ammonium tungstate solution containing 193 g/L W was obtained with a stripping rate of 98.10%under the optimized conditions.

红土镍矿硝酸加压浸出渣制备电池级磷酸铁

近年来,在我国“碳达峰”和“碳中和”目标的引领下,新能源行业发展迅速,新能源汽车的推广与使用促进了锂离子电池行业的蓬勃发展。作为三元锂电池的关键原材料,镍的需求量不断增加。但由于硫化镍矿日益枯竭,红土镍矿逐渐成为了主要的提镍原料,在镍产量中占比超过70%。褐铁型红土镍矿在红土镍矿中占比超过60%,经硝酸加压浸出(NAPL)提取镍钴后产生的浸出渣中含有丰富的有价金属资源(铁含量>60%),浸出渣的综合利用对资源回收和环境保护具有重要意义。以褐铁型红土镍矿硝酸加压浸出渣为原料,在磷酸单一介质中制备电池级磷酸铁材料。以磷酸为介质,通过预浸、溶解实现浸出渣中铁的高效提取。预浸时磷酸溶液浓度较低,可以使含铁相初步转型为FePO_(4)·2H_(2)O,同时除去浸出渣中Cr、Mg、Al等杂质元素。然后采用高浓度磷酸溶液溶解处理预浸渣,实现Fe的完全溶解。最后稀释调节pH值直接沉淀制备磷酸铁,得到FePO_(4)·2H_(2)O产品,该产品不含杂质元素Mg、Si,Cr、Al的含量为0.019%、0.016%。通过XRD、SEM、EDS等技术手段对预浸渣和磷酸铁产品的物相组成和微观形貌进行了研究,明确了预浸过程可实现铁由Fe_(2)O_(3)向FePO_(4)·2H_(2)O的转变,最终产品的晶体结构与标准磷酸铁相匹配。由磷酸铁合成的磷酸铁锂材料也表现出优异的电化学性能。该研究有望实现对褐铁型红土镍矿硝酸加压浸出渣中宏量组元铁的高值化利用,从而优化磷酸铁制备工艺。

Distribution of REE of Phosphate Concentrate in Wet-Phosphoric Acid Process

There exists the most important REE-bearing phosphorite deposit in Southwest of China. Due to the fact that the REE are present in the form of ions in the lattices of collophanite or carbonatfluorapatite, the REE can be enriched in phosphate concentrate by flotation method. The phosphate concentrate is the main raw materials to produce phosphoric acid, therefore, it is significant to further investigate the distribution rule of REE in wet process. In this paper, the single leaching and recycled leaching technology were carried out to investigate the effect of various parameter conditions on distribution of REE in products. The REE compositions of products were analyzed by Inductively Coupled Plasma Emission Mass Spectrometry (ICP-MS) method. It was found that the acidic value of leaching liquor was the main effect factor on the distribution of REE in products. In single leaching stage, P2O5 concentration of leaching liquor slightly varied from 8% to about 10% when the excessive coefficient of sulphuric acid ranged from 1.03 to 1.05, and the distribution proportions of ∑REO in phosphoric acid solution was lower than 40%. However, in recycled leaching process(the condition similar to practical wet process), with an increase of P2O5 concentration as well as the acidic value of leaching liquor, the distribution proportions of ∑REO in phosphoric acid solution could be decreased to 2.56%. That is to say that under the condition similar to practical wet process, more than 90% of REE of phosphate concentrate became precipitation entering into the phosphogypsum product. This investigation will provide valid reference for reasonably recovering or reserving REE in wet-phosphoric acid process.

Leaching behavior of phosphorous compounds from sewage sludge ash based on quantitative X-ray diffraction analysis

Phosphorus(P)is an essential and limited resource.Incineration sewage sludge ash(ISSA)contains a high amount of P,which can be recovered using chemical leaching methods.However,the recovery ratio depends on the speciation of P and the leaching conditions.In this study,hydrochloric acid was used as a leaching agent,and the effects of the hydrochloric acid concentration,leaching time,temperature,and liquid-solid ratio on the P leaching ratio were investigated.Furthermore,the co-leaching of macro-metals Ca,Al,Fe,and Mg was analyzed.The results showed that P leached rapidly within 30 min,where the leaching rate reached more than 80%and then gradually stabilized.The leaching concentrations of Ca and Mg had a significant correlation(correlation coefficient r^(2)>0.90),and both were leached completely.Al and P had similar leaching patterns,where the leaching rates increased initially and then decreased with time at 0.2 mol/L HCl.According to X-ray diffraction analysis and Rietveld refinement,the P in ISSA was mainly present in the forms of Mg_(3)Ca_(3)(PO_(4))_(4) and AlPO_(4).When leached using 0.2 mol/L HCl at 55℃ with a liquid-to-solid ratio of 20 L/kg,the AlPO_(4) and Fe_(3)(H_(2)O)_(3)(PO_(4))_(2) in ISSA dissolved initially and then precipitated on the surface of the solid phase,thereby impeding further P leaching.

微波辅助酸浸实现磷石膏中稀土元素有效浸出

磷石膏(PG)是磷肥工业中一种含有稀土元素的废弃物,稀土元素含量低但储量大,从磷石膏中回收稀土元素具有较大的经济价值。本研究重点是磷石膏的深入表征以及浸出过程研究,采用微波辅助酸浸磷石膏实现稀土元素浸出的方法。结果表明:在微波辅助条件下,当硝酸浓度为2.0 mol/L,固液比为6∶100(g/mL),浸出温度为80℃,浸出时间为30 min时,磷石膏稀土总元素的浸出率为96.52%。借助SEM、XRD探究微波酸浸机理,进一步表明在微波酸浸过程中由于微波、高温等相互作用会破坏晶体结构使颗粒细化,从而促使微波浸出效果比水浴浸出效果高12.3%。

赤泥磷酸浸出选择性脱硅

赤泥是铝土矿生产氧化铝过程中产生的固体残渣,也是一种低品位含铝资源,但因其SiO_(2)含量高、铝硅比低,难以直接通过碱浸回收Al_(2)O_(3)。以赤泥钠化还原焙烧—磁选后所得非磁性物为原料,磷酸为浸出剂,实现了硅的选择性浸出及铝、硅之间的有效分离,为后续氧化铝的提取创造了有利条件。在磷酸浓度1 mol L、液固比15 mL g、浸出温度50℃、浸出时间60 min的条件下,SiO_(2)的浸出率达82%,浸出渣铝硅比为4.4,较非磁性物提高了2倍左右,实现了铝、硅之间的较好分离。磷酸浸出渣再碱浸,采取35%NaOH溶液,浸出温度260℃,Al_(2)O_(3)的浸出率从未脱硅前的69%增大至93%。磷酸选择性浸出非磁性物中硅的原因是铝硅酸盐矿物中含硅组分溶解在酸溶液中,而含铝组分与磷酸反应转变成了AlPO_(4)不溶性沉淀。

某磷灰石浮选精矿磷酸浸出提纯试验研究

为进一步提高磷灰石浮选精矿纯度,创新性地提出了采用磷酸浸出法脱除磷灰石浮选精矿中的方解石和白云石等碳酸盐脉石矿物的方法。酸浸条件对磷灰石提纯效果的影响规律研究表明,在磷灰石粒度为-38μm,稀磷酸浓度为10%,液固比为4∶1,反应温度为20℃,反应时间为240 s条件下进行磷灰石浮选精矿的磷酸浸出试验,可将纯度为86.88%的磷灰石提纯至99.36%。酸浸机理研究表明,磷灰石不与磷酸发生反应,而方解石和白云石均可以与过量的磷酸反应生成溶于水的物质而被脱除;经过磷酸浸出提纯后的磷灰石纯度较高,结晶良好。研究结果对碳酸盐矿物钙质型磷矿的提纯降杂具有重要参考意义。

赤泥磷酸浸出液中稀土的萃取行为研究

赤泥是铝土矿生产氧化铝过程中产生的固体残渣,含有铁、硅、铝、钛及稀土等多种有价组分。在已预先分离赤泥中大部分铁、硅、铝、钛的前提下,采取溶剂萃取的方式对赤泥磷酸浸出液中的稀土作进一步分离与纯化,研究了在中性磷型萃取剂TBP、酸性磷型萃取剂P204和P507分别作用下,稀土La、Ce、Sc、Y以及主要杂质组分Al、Fe、Ti、Ca的萃取行为,结果表明:TBP对稀土的萃取效果较差,P507对稀土Sc、Y及杂质Fe、Ti的萃取能力较强,P204萃取稀土的能力优于P507;采用质量分数2%P204作为萃取剂,在溶液pH为1.5、相比为1∶3的条件下,磷酸浸出液中Sc、Y的萃取率分别为90%、99%,La、Ce及杂质Fe、Al、Ti、Ca萃取率均低于5%;将P204质量分数升至20%,La、Ce萃取率可分别达到85%、95%。因此可通过采用P204分步萃取的方式有效分离磷酸浸出液中的稀土。

响应曲面法优化微波浸出废弃荧光粉中稀土元素钇和铕

某废弃荧光粉中含有49.56%的稀土氧化物,具有极大的回收利用价值。为优化该废弃荧光粉中稀土元素Y和Eu的微波浸出工艺,使用响应面法对浸出工艺进行优化,选取对浸出过程有显著影响的反应时间、微波功率和盐酸浓度三个因素作为考察因素,建立了微波功率、反应时间和盐酸浓度及三者间交互作用对稀土元素Y和Eu浸出率影响的二次多项式回归模型。研究结果表明,反应时间对稀土元素Y和Eu浸出率的影响最显著,微波功率和盐酸浓度影响次之,反应时间和盐酸浓度的交互影响对稀土元素Y和Eu的浸出率具有显著性影响。最佳优化工艺条件为:微波功率850 W、反应时间76.10 min、盐酸浓度3.58 mol/L,在此条件下,稀土元素Y和Eu浸出率的分别为97.44%和89.20%,与模型预测值十分接近,证明所用模型是可靠和准确的。

Effects of mechanical activation on the kinetics of terbium leaching from waste phosphors using hydrochloric acid

The effect of mechanical activation （MA） on the kinetics of terbium （Tb） leaching from waste phosphors using hydrochloric acid was investigated. Leaching kinetics, such as apparent reaction rate, activation energy and reaction order, were determined using the shrinking-core model and the Arrhenius equation. Results obtained from experiments with different concentrations of HC1 and under different leaching temperatures were used for the determinations. The impacts of factors such as rotational speed, HC1 concen- tration and leaching temperature on the leaching rate of Tb were also discussed. The results showed that MA could dramatically increase the leaching rate of Tb from waste phosphors, and the apparent reaction rate （kap） of leaching was accelerated as well. For inactivated waste phosphors, the apparent activation energy （Eap） was 52.82±3.95 kJ/mol, indicating that the rate-controlling step of the leaching process was the chemical reaction. The Eap dropped to 25.96 ±3.90 kJ/mol and 10.96±2.79 k J/tool when the waste phosphors were mechanically activated at rotational speeds of 400 and 600 r/min, respectively; the leaching process transformed to a hybrid （chemical-reaction and diffusion） control process, and even a reagent-diffusion （through the product layer） control process. The apparent reaction order for Tb leaching from 400 r/min-activated waste phosphors was 2.49±0.11, and it decreased to 1. 16±0.17 when the rotational speed of 600 r/min was used. Kinetics results indicated that MA could make Tb leaching occur spontaneously, and thc activation intensity of waste phosphors was strengthened with higher rotational speed.

Leaching isomorphism rare earths from phosphorite ore by sulfuric acid and phosphoric acid

Most of the phosphorite deposits in the world contain isomorphism rare earths （RE） which are considerably difficult to be leached into solution in the wet phos- phoric acid process. In this work, a systematic study of leaching RE using sulfuric acid, phosphoric acid, mixed acid and two-step leaching of phosphoric acid and sulfuric acid was performed. The aims are to illuminate the main factors that inhibit RE leaching and to provide insights into the further enrichment of RE in the wet phosphoric acid solution. The results indicate that H2SO4 is not an effective acid for leaching isomorphism RE from phosphorite ore. The low RE leaching efficiency attributes to the RE cocrystallized and encapsulated by phosphogypsum （PG） as well as the precipitation of RE by RE sulfates or phosphates. High concentration of H3PO4 can enhance the dissolution and diffusion of RE ions. Hence, the optimized leaching mode of improving RE leaching efficiency is to adequately dissolve phosphorite ores in high concentration of H3PO4 solution and then add H2SO4 to crystallize PG. The effect of corystallization or encapsulation of PG on RE can be decreased due to the crystallizing mode of PG in the bulk solution instead of on the interface of solid reactants. RE leaching efficiency can be high up to 65% by the optimized leaching mode.

One-step separation and recovery of rare earth and iron from NdFeB slurry via phosphoric acid leaching

The recovery of rare earth elements(REEs)from NdFeB slurry by traditional hydrometallurgy has been limited becuase a large number of REEs are lost during separation together with iron.In this paper,a simple and sustainable method is proposed to efficiently separate and recover REEs and iron from NdFeB slurry.REEs were recovered by one-step selective precipitation in phosphoric acid,and the dissolved iron was recovered by oxalic acid.Phosphoric acid leaching results show that under the conditions of 4 mol/L phosphoric acid,80℃,L/S of 30:1 and 90 min,the leaching efficiencies of Fe and REEs reach 98.76%and1.09%,respectively.While the rest of REEs remained in the leaching residue in the form of REEPO_(4)·nH_(2)O precipitation.Subsequently.the mixed rare earth oxide(rare earth oxalate roasted at 800℃)and FeC_(2)O_(4)·2 H_(2)O are obtained by oxalic acid precipitation with purities of 99.49%and 97.17%from the REEPO4·nH_(2)O dissolving solution and the phosphoric acid leaching solution.Moreover,the phosphoric acid is regenerated while recovering iron,and it can be reused in the phosphoric acid leaching step after removing the impurity C_(2)O_(4)^(2-).In summary,this work provides an efficient and environmentally friendly method for recovering REEs and iron from NdFeB slurry waste.

从废弃CRT荧光粉中回收稀土的研究

废弃CRT荧光粉是一种含有稀土钇和铕的二次资源,具有较高的回收价值。本研究采用浓硫酸定向转型-水浸的方法高效回收废CRT荧光粉中的稀土资源。通过浓硫酸定向转型,使废弃CRT荧光粉中的稀土和硫酸根结合形成稀土硫酸盐,而负二价的硫与浓硫酸反应形成单质硫气体,避免了剧毒气体硫化氢的产生,之后稀土硫酸盐经过水浸后进入溶液,达到了高效绿色回收稀土的目的。研究表明,在最优条件:酸样比8:5 mL/g,转型温度85℃,转型时间30 min,液固比10:1 mL/g,水浸温度85℃,水浸时间30 min下,稀土钇和铕的平均浸出率达到了99.77%和99.24%,并获得了含钇8.26 g/L和含铕0.57 g/L的浸出液。

低品位钨锡混合矿酸碱联合浸出工艺研究

针对南岭钨锡多金属资源综合开发利用面临的技术难题,采用酸碱联合分解工艺处理低品位钨锡混合矿,实现了钨的高效浸出与锡的资源化富集。研究了浸出过程中各参数对钨矿物分解及锡石反应行为的影响,结果表明:矿物中白钨成分的分解需高浓度盐酸提供足够的推动力,过高的磷酸浓度不利于矿物的分解;黑钨组分采用传统的碱压煮法实现高效分解,伴生的锡资源富集在碱分解渣中。酸浸过程以5mol/LHCl+75g/LH_(3)PO_(4)混合酸作为浸出剂,在液固比2.5∶1、反应温度80℃、反应时间2h的条件下,W浸出率为77.89%,渣含钨为4.58%;碱浸过程控制NaOH浓度为300g/L,液固比为1.25∶1,反应温度为130℃、反应时间为1.5h,可使W浸出率达到99.79%,渣含钨仅为0.06%。混合矿中锡的赋存状态复杂,在酸、碱浸出体系中均有少量损失,碱煮渣中锡含量富集至11.21%,可作为锡中矿进行资源化利用。

有机无机肥配施对玉米产量及土壤氮磷淋溶的影响

【目的】氮、磷是农作物生长所必需的营养元素,对提高农作物产量和改善产品品质均有重要作用,但由于肥料不合理施用,农田土壤中养分大量盈余,在降雨或灌溉条件下易随水流失,导致水环境质量下降。因此,研究有机无机肥料配施对土壤氮、磷淋溶风险的影响,可为地下水环境质量保护提供依据。【方法】采用田间渗滤池法,对华北地区玉米季氮磷淋溶状况连续5年进行监测,具体施肥处理如下:对照(不施用氮肥,PK)、单施化肥(NPK)、单施有机肥(与NPK处理等氮量,SW)、有机肥无机肥料配施(用猪粪中氮替代50%NPK处理中氮用量,SNP)。采集120 cm处淋溶水,测定氮、磷含量,研究在总氮投入量相同条件下,有机无机肥料配施对华北地区玉米产量及土壤剖面120 cm处氮磷淋溶的影响。【结果】1)有机无机肥料配施(SNP)处理,可以保证玉米较高产量,5年平均产量较单施化肥处理(NPK)提高10.3%。2)有机无机肥料配施可以显著减少总氮(TN)淋溶量,SNP处理较NPK处理减少71.4%;NPK处理淋溶水中NO-3-N浓度显著高于SNP处理,其平均浓度分别为54.93 mg/L、13.47 mg/L。3)在等氮量投入条件下,有机肥的投入带入了大量磷素,单施有机肥(SW)较NPK处理总磷(TP)淋溶量增加了0.6倍,分别为0.056 kg/hm2、0.035 kg/hm2;淋溶水中TP浓度分别为0.09 mg/L、0.066 mg/L。在氮磷养分淋溶损失中,NO-3-N占淋溶水TN的80%以上,可溶性总磷(TDP)占淋溶水TP的70%左右。4)在监测淋溶水中,NPK处理NO-3-N平均浓度已超过我国地下水Ⅲ类水质量标准(GB/T 14848-9),SW处理TP平均浓度0.09 mg/L,也高于水体富营养化TP浓度(0.02 mg/L)的临界值,可对水体造成污染。【结论】在氮磷养分淋溶损失中,NO-3-N占淋溶水TN的80%以上,TDP占淋溶水TP的70%左右。采用猪粪氮替代50%化肥氮素的有机无机肥料配施处理,5年玉米平均产量显著高于单施化肥处理,证明该施肥方法不仅可以确保产量,还可降低氮素淋溶,基本保证淋溶水中NO-3-N浓度低于地下水Ⅲ类水质量标准(GB/T 14848-9)。

返酸浸出磷矿中的稀土

采用湿法磷酸工艺的返回酸浸出磷矿中伴生稀土与磷,稀土与磷以磷酸二氢盐的形式进入溶液。考察温度、浓度、时间、液固比等因素对稀土与磷浸出的影响。结果表明,适宜的浸出条件为:返回酸浓度25%、温度65℃、液固比10∶1、浸出时间8h,在此条件下,稀土浸出率可达90.4%,磷浸出率达98.7%。

高磷铁矿石降磷的现状与存在问题探讨

介绍了国内外高磷铁矿石降磷方法的现状,提出了目前铁矿降磷方法中存在的问题,并对铁矿降磷未来的发展方向进行了探讨。

稀土磷精矿的硫酸循环浸出

采用硫酸循环浸出稀土磷精矿,对磷酸溶液和石膏洗液中P2O5与稀土的富集以及浸出率的情况进行研究。结果表明:在硫酸过量系数为1.03,液固比3.5∶1,时间3h,温度75℃的浸出条件下,再经2次石膏洗涤后,磷酸溶液中P2O5的浓度可以富集到280g/L,ΣREO的浓度可以富集到340mg/L左右,P2O5和ΣREO的浸出率分别为92.46%和31.76%。

磷矿脱镁研究进展

磷矿脱镁在湿法制备磷酸工艺中至关重要。本文分析了磷矿中的镁杂质(主要以白云石形式存在)对磷化工生产过程的影响,综述了近几十年来磷矿脱镁的工艺方法及应用,重点总结了浮选法和酸式浸提法在脱镁研究中的应用及其效果。浮选法主要采用反浮选法将胶磷矿和白云石分离,常在弱酸性介质中用捕收剂将白云石浮起以达到脱镁的目的,捕收剂的选择是浮选法成功的关键。酸式浸提脱镁的工艺简单,易操作,工业化应用前景广阔,是近年来的研究热点。酸式浸提法主要是利用白云石和磷矿物与酸性物质反应活性的差异,在浸提液酸性环境中选择性地溶解白云石,从而达到脱镁的效果。现有的脱镁方法都不可避免地面临磷损失和二次污染等问题,所以,开发复合型的除镁工艺和经济环保的新方法将是今后的研究方向。

连续淋洗对山东省主要土壤磷素有效性及磷库的影响

研究采取室内模拟降雨淋洗的方法,研究了连续淋洗对山东省3大土类磷素有效性和磷库的影响。结果表明,3种土壤的磷淋失量均随着供磷水平的提高而升高。3种土壤出现磷淋失量峰值的时间有着明显差异,褐土施磷处理的磷淋量峰值分别出现在第3 d,4 d和5 d;而潮土高磷和低磷处理的磷淋洗最高值分别出现在第2 d和3 d;而棕壤不同施磷处理的磷淋洗高峰值均出现在第2 d。在相对较低的施磷水平下(P3以下),3大土类的速效磷含量基本均保持在20μg/g左右,再提高供磷水平,褐土和棕壤的土壤速效磷含量随施磷量的增加显著升高,而潮土的速效磷含量则随着施磷量的增加先升高后降低。在3大土类中,全磷含量最高的是褐土,其次是潮土,再次是棕壤。在淋洗条件下,褐土的土壤磷库相对变化不大,而潮土和棕壤的磷库则随施磷量的变化有着较大的起伏。因此,施磷水平控制在P3水平(180 kg P/hm2),3大土壤的磷淋失量较低,土壤速效磷变化不大,有利于减少土壤磷素淋失到水体的风险,也保证了土壤磷的供应能力。