Amenability for processing of oolitic iron ore concentrate for phosphorus removal

Beneficiation routes aimed at dephosphorisation of oolitic gravity magnetic concentrate and involving a combination of roasting, re-grinding, magnetic separation and water and acid leaching are investigated. Roasting was carried out at 900 °C for 1 h without or with lime or sodium hydroxide as roasting additives. When additives were used, cement phases of Si–Al–Na–Ca–O type were detected as well as the mineral giuseppettite. During the thermal process sodium silicate is liquefied and the newly formed phases coat the oolites and penetrate inside the cracks. Energy Dispersive Spectroscopy analysis has indicated that the zone surrounding the oolites consists of Na, Al and Si phases with part of phosphorus being captured there. As a result of the alkaline roasting, goethite is partly transformed to magnetite and this reduction is reinforced with an increase in sodium hydroxide dosage. Investigation of redistribution of phosphorous shows that it could be only partly separated if leaching is not accompanied by re-grinding and physical separation. The recommended dosage of the reductive agent for the final flowsheet is 8 mass% ratio to concentrate. Grinding to a mean size of 0.040 mm, with water and acid leaching and double magnetic separation creates conditions to obtain a high-quality iron concentrate with 65.97% Fe and recovery of 92.43%, with simultaneous decrease in the phosphorus content from 0.71% to 0.05%.     

焙烧-浸出-磁选回收铜渣中的铁

以煤粉作还原剂, 采用焙烧-浸出-磁选工艺对某铜渣中的铁进行了回收实验研究。探讨了焙烧温度、焙烧时间、煤粉用量、碳酸钠用量等因素对铁回收的影响, 最佳工艺条件为: 焙烧温度800 ℃, 焙烧时间60 min, 煤粉用量1%, 碳酸钠用量10%, 在此条件下获得的焙砂经进一步稀酸浸出和磁选, 可获得铁品位62.53%、铁回收率70.82%的铁精矿。     

国外某高铝赤褐铁矿选矿试验研究

对国外某高铝赤褐铁矿进行了选矿试验研究。采用还原磁化焙烧-磁选工艺, 可获得精矿铁品位58.26%、铁回收率80.53%的试验指标; 采用钠化还原磁化焙烧-磁选工艺, 可获得精矿铁品位63.48%、回收率95.45%的试验指标。探索了在富集铁的同时富集镍、降低铁精矿中Al₂O₃含量的可行性。     

Chemical and mineral transformation of a low grade goethite ore by dehydroxylation,reduction roasting and magnetic separation

The utilization of abundant low grade goethite (α − FeOOH) ores is potentially important to many countries in the world, especially Australia. These ores contain many detrimental impurities and are difficult to upgrade to make suitable concentrates for the blast furnace. In this paper, chemical and mineral transformations of a goethite ore were studied by dehydroxylation, reduction roasting in CO and CO₂ gas mixtures, and magnetic separation. The goethite sample was taken from a reject stream at an iron ore mine from the Pilbara region, Western Australia. The roasting temperature range investigated was 400–700 °C. Chemical and mineralogical analysis was conducted using XRF, XRD, optical microscope, EPMA, and SEM. Magnetic separation was conducted using a Davis tube tester and a high intensity magnetic separator.The results show that reduction roasting can remove moisture and impurities but does not significantly change the Fe content in the feed. However, reduction roasting transforms goethite to hematite and eventually maghemite which can be recovered by magnetic separation, allowing upgrading. Further studies are needed to optimize the reduction roasting and correlate it with the magnetic separation to maximize the efficiency of iron upgrading.     

Comprehensive processing of low grade sulphidic molybdenum ores

Low-grade sulphidic molybdenum ores were treated by using a combined processing route for a comprehensive recovery of molybdenum, copper, and other minor elements. As the first step, oxidation roasting was used to convert most of sulphides into metal oxides, during which 85–90% of sulphur was removed. Then both water and dilute sulphuric acid leaching of the roast were tested, in order to remove silica, iron and other impurities from the roast. Both copper and molybdenum were recovered one after another from the filtrates via cementation by iron powder under controlled temperature and pH conditions. Recovery for both elements was in all cases over 99%. Reasonable separation efficiency for copper and molybdenum was achieved from the water leach solutions. The leached cakes were dissolved in ammonia to recover the molybdenum by crystallisation as ammonium-dimolybdate. The proposed roasting, leaching and separation steps give a feasible alternative for a comprehensive processing of low grade molybdenum ores.     

废铝基催化剂综合利用新工艺研究

在X-射线衍射物相分析及探索性试验研究的基础上,开发了一种新的工艺,对废铝基催化剂中的有价元素进行综合回收。该工艺采用先提取铝后回收镍钴钒钼的技术,用钠化焙烧强化氧化铝的提取,促进了镍钴钒钼与铝的分离,为后续有价元素的综合回收创造了条件。试验结果表明,焙烧后废铝基催化剂中氧化铝的溶出率可达97％;采用碳分法从溶出氧化铝后的铝酸钠母液中制备氧化铝,产品可达国家一级标准,回收率为90％;溶出铝后的镍钴渣在适宜条件下进行浸出,镍、钴的浸出率可达98．2％和98．5％;强碱性阴离子树脂202可从铝酸钠溶液中选择性吸附钼,树脂的交换容量可达85mg／mL湿树脂,树脂的解吸率为80．8％。     

A novel method to recover zinc and iron from zinc leaching residue

A novel method to recover zinc and iron from zinc leaching residue (ZLR) by the combination of reduction roasting, acid leaching and magnetic separation was proposed. Zinc ferrite in the ZLR was selectively transformed to ZnO and Fe₃O₄ under CO, CO₂ and Ar atmosphere. Subsequently, acid leaching was carried out to dissolve zinc from reduced ZLR while iron was left in the residue and recovered by magnetic separation. The mineralogical changes of ZLR during the processes were characterized by XRF, TG, XRD, SEM–EDS and VSM. The effects of roasting and leaching conditions were investigated with the optimum conditions obtained as follows: roasted at 750 °C for 90 min with 8% CO and CO/CO + CO₂ ratio at 30%; leached at 35 °C for 60 min with 90 g/l sulfuric acid and liquid to solid ratio at 10:1. The iron was recovered by magnetic separation with magnetic intensity at 1160 G for 20 min. Under the optimum operation, 61.38% of zinc was recovered and 80.9% of iron recovery was achieved. This novel method not only realized the simultaneous recovery of zinc and iron but also solved the environmental problem caused by the storage of massive ZLR.     

高铝高硅褐铁矿钠化焙烧-磁选试验研究

针对某高铝高硅难选褐铁矿(Al₂O₃含量26.11%、SiO₂含量13.88%)进行了钠化焙烧-磁选试验研究。通过单因素试验和正交试验探讨了钠盐种类、钠盐用量、焙烧时间、焙烧温度、磁选粒度、磁选强度对选别指标的影响, 结果表明, 在焙烧温度1 050 ℃、焙烧时间40 min、Na₂CO₃用量12%、煤粉用量20%、磨矿细度-0.038 mm粒级占98.86%、磁场强度200 kA/m条件下可获得铁品位57.91%、铁回收率97.50%的铁精矿。钠化焙烧后产品再经阶段磨矿、阶段磁选可获得铁品位62.04%、铁回收率60.90%的铁精矿。     

An innovative process for extracting boron and simultaneous recovering metallic iron from ludwigite ore

Ludwigite ore has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination in China. Boron–iron separation and dissolution activity of boron-bearing minerals in alkaline liquor are the two key issues in the utilization of ludwigite ore, governing the boron recovery as well as operating cost. This paper proposes an innovative process for extraction of boron and iron from ludwigite ore based on coal-based direct reduction process with sodium carbonate (Na₂CO₃). The novel process involves reduction roasting, combined leaching and grinding of reduced ludwigite ore, followed by magnetic separation of leach residue, and experimental validation for each of the processing steps is demonstrated. Alkali-activation of boron and metallization of iron were synchronously achieved during carbothermic reduction of ludwigite ore in the presence of Na₂CO₃. Consequently, boron was readily extracted in the form of sodium metaborate (NaBO₂) with water at room temperature during ball mill grinding, and metallic iron powder was recovered from the leaching-filtering residue by magnetic separation. Boron extraction of 72.1% and iron recovery of 95.7% with corresponding iron grade of 95.7% in the magnetic concentrate were achieved when ludwigite ore was reduced with 20% sodium carbonate at 1050 °C for 60 min.     

Activation pretreatment of limonitic laterite ores by alkali-roasting method using sodium carbonate

Activation pretreatment of Cr-containing limonitic laterite ores by Na₂CO₃ roasting to remove Cr and Al, as well as its effect on Ni and Co extraction in the subsequent pressure acid leaching process were investigated. X-ray diffraction (XRD), thermogravimetric (TG), and scanning electron microscopy/X-ray energy dispersive spectroscopy (SEM/XEDS) techniques were used to characterize the laterite ores and the water leaching residues of alkali roasting and found that goethite is the major Ni-bearing mineral and chromite the minor one. Alkali-roasting pretreatment breaks the mineral lattices of the laterite, exposing their Ni and Co, which leads to higher extraction of these two metals under milder operation conditions in the subsequent pressure acid leaching process. Experimental results showed that the leaching of Cr and Al were up to 99 wt% and 80 wt%, respectively, under optimal alkali roasting and water leaching conditions. Compared with the direct pressure acid leaching of the raw laterite ores, leaching of Ni and Co increased from 79.96 wt% to 97.52 wt% and 70.02 wt% to 95.33 wt%, respectively, after alkali-roasting activation pretreatment was performed. Meanwhile, the grade of acid leaching iron residues increased from 55.31 wt% to 62.92 wt%, and these residues with low Cr content could be more suitable as the raw materials for iron-making.     

Atmospheric leaching characteristics of nickel and iron in limonitic laterite with sulfuric acid in the presence of sodium sulfite

Atmospheric leaching of nickel from limonitic laterite ores is regarded as a promising approach for nickel production, despite its low nickel recovery and slower leaching rate than high pressure acid leaching. Sulfur dioxide can enhance the sulfuric acid leaching of laterite, but its behavior for enhancing atmospheric sulfuric acid leaching was uncertain due to SO₂ losses and emission. In this study, sodium sulfite was used as a substitute for SO₂ gas in the leaching and the sulfuric acid leaching characteristics of Ni and Fe from a limonitic laterite in the presence of sodium sulfite were investigated. A linear correlation exists between the extraction of Ni and Fe, indicating the difficulty in selective leaching of Ni over Fe. Most nickel is isomorphically substituted within the goethite and it is difficult to dissolve in a high oxidation–reduction potential solution environment, resulting in a low nickel recovery. SO₂(aq) generated from the reaction of sodium sulfite in sulfuric acid solution, lowers the potential for the reducing reaction of FeOOH to give Fe²⁺, accelerating the iron extraction and nickel liberation from goethite.     

Microwave carbothermic reduction roasting of a low grade nickeliferous silicate laterite ore

The known resources of nickel sulphide ores are quickly diminishing and in order to satisfy future nickel demands, nickel laterite deposits are being investigated as an alternative. Currently, expensive leaching and smelting processes are used to process the nickel laterite ores. The objective of the present research was to produce a high grade nickel concentrate via microwave carbothermic reduction roasting followed by magnetic separation. A thermodynamic model was developed for the roasting process in order to determine the optimum experimental conditions. The experimental variables investigated were: microwave energy and argon shrouding for the reduction tests and the magnetic field strength for the concentration stage. The behaviours of nickel and cobalt were studied in the reduction and magnetic separation processes. By optimizing the reducing and magnetic separation conditions, a high grade concentrate containing 9.2% nickel with a nickel recovery of 88.8% was achieved.     

某难选铁矿石煤基直接还原—磁选试验研究

某难选铁矿石属"江口式"微细粒嵌布混合型铁矿石。对该矿石进行了煤基直接还原—磁选试验研究,结果表明,以30%的烟煤为还原剂,15%的NM为助熔剂,将矿石在1250℃的温度下直接还原焙烧80min,焙烧矿经两段阶段磨矿—阶段磁选,可获得铁品位为91.93%,铁回收率为83.87%的直接还原铁产品。     

白云鄂博中贫氧化矿微波磁化焙烧—磁选试验研究

采用微波碳热还原技术,对白云鄂博中贫氧化矿进行磁化焙烧,研究了微波焙烧温度、配碳量、保温时间对其磁化率的影响规律以及温度对磁选效果的影响。结果发现:在650℃,0.5%配碳量,焙烧10min的条件下矿物的还原效果最佳,其磁化率为2.36,接近理论值。由于矿粉高温下有烧结现象,570℃焙烧矿磁选精矿的品位最高。精矿经再磨再选,通过控制二次磁选的磁场强度,可分别获得品位65%和回收率58.6%,或品位63%和回收率72.8%的铁精矿。铁精矿中P,S,SiO2,K2O含量较低,基本达到炼铁入炉要求,稀土在尾矿中富集2倍多。     

某低品位铜钼矿石选矿试验

某铜钼矿石中钼和铜含量较低,分别为0.081%和0.19%,且铜矿物嵌布粒度较细并与钼矿物密切共生,给两者分离带来一定困难。采用钼铜混合浮选-混合精矿精选1次后再磨再精选-铜钼分离流程对该矿石进行选矿试验,混合浮选时以石灰和水玻璃为调整剂、煤油和丁铵黑药为捕收剂,铜钼分离时以石灰、水玻璃和SK为调整剂、煤油为捕收剂,在1段和2段磨矿细度分别为-0.074 mm占70%和-0.045 mm占95%条件下,获得了钼品位为45.30%、钼回收率为84.16%的钼精矿和铜品位为14.28%、铜回收率为89.59%的铜精矿,为该矿石的开发提供了技术依据。     

大西沟菱褐铁矿表面磁化焙烧-强磁选新工艺研究

对大西沟铁矿进行了表面磁化焙烧-强磁选预富集新工艺探索。结果表明,采用表面磁化焙烧-强磁选预富集技术,在尾矿铁损失率仅10.30%的情况下,可以将菱褐铁矿品位从23.93%提高至33.89%,抛出产率36.68%、品位仅6.72%的尾矿。表面磁化焙烧-强磁选一粗两精流程可获得强磁精矿品位42.15%、回收率69.39%,总尾矿品位仅11.44%。研究成果可为菱褐铁矿合理经济利用提供新的方案。     

东鞍山铁矿混磁精矿悬浮焙烧—弱磁选试验研究

磁化焙烧技术是处理难选铁矿资源典型、有效的方法。采用实验室间歇式悬浮焙烧炉,以高纯N2和H2的混合气体作为还原气体,在气体流量为8 m3/h、H2浓度为30%、焙烧温度为650℃、焙烧时间为8 s条件下,对东鞍山铁矿铁品位为43.92%为的混磁精矿进行悬浮焙烧,焙烧产品磨细至-0.038 mm占85%,在磁场强度为80 k A/m条件下弱磁选,获得了铁品位为65.48%、回收率为88.26%的精矿。为我国含碳酸盐铁矿资源的高效利用提供了新途径。     

某含银多金属锰矿选矿富集工艺研究

从工艺矿物学的角度分析了某含银多金属锰矿实现锰、银分离的难点,参照类似性质矿石的处理工艺,并结合研究对象的性质特点,指出其合适的开发利用工艺为干式筛分分级-粗粒干式强磁选-细粒湿式强磁选-混合精矿湿法冶金浸出。通过实验室试验,最终获得锰品位31.59%、银品位657.9 g/t、铁品位11.72%,锰回收率90.24%、银回收率91.29%、铁回收率78.51%的混合精矿,为大规模、高效率、低成本开发利用该矿石奠定了基础。     

酒钢-1mm镜铁矿粉矿微波磁化焙烧—弱磁选试验

鉴于酒钢-1 mm镜铁矿粉矿采用常规选矿方法难以获得好的分选指标,进行常规磁化焙烧—弱磁选又需解决球团问题,以哈密烟煤为还原剂,对该粉矿开展了微波磁化焙烧—弱磁选研究,考察了煤粉用量、微波功率、焙烧温度、焙烧时间、焙烧产品磨矿细度和弱磁选磁场强度对所获铁精矿指标的影响。试验结果表明,在煤粉与矿石的质量比为5%、微波功率为1 k W、焙烧温度为550℃条件下将该粉矿微波磁化焙烧15 min,然后将焙烧矿磨细至-0.074 mm占85.65%,在92.16 k A/m磁场强度下进行1次磁选管选别,可获得铁精矿铁品位为55.10%、铁回收率为86.65%的较好指标,从而为该-1 mm镜铁矿粉矿中铁矿物的高效回收提供了一种新思路。     

某褐铁矿微波磁化焙烧-弱磁选试验

以河南义马褐煤为还原剂,对印尼某褐铁矿进行微波磁化焙烧-弱磁选试验,主要考察了焙烧时间、焙烧矿磨矿细度及磁场强度对精矿指标的影响。试验结果表明：在还原剂配加量为5.4%、微波功率为1 kW的固定条件下,当焙烧时间为45 min（终点温度840 ℃）、焙烧矿磨矿细度为-200目占97.17%（-325目占82.03%,-400目占64.15%）、磁场强度为150 kA/m时,可获得铁品位为57.28%、铁回收率为83.95%的铁精矿。试验中发现,微波焙烧产品可以很容易就被磨得很细。