298.2 K四元体系MgCl2+CaCl2+AlCl3+H2O 相平衡研究

为获取粉煤灰含铝溶浸液中铝与共存钙、镁之间的作用规律,采用等温溶解平衡法开展了298.2 K时四元体系MgCl₂+CaCl₂+AlCl₃+H₂O相平衡研究,测定了平衡液相组成及平衡液相密度,同时,绘制了该四元体系的干基相图、水图、密度-组成图。研究发现:298.2 K四元体系MgCl₂+CaCl₂+AlCl₃+H₂O 稳定相图由2个共饱点、4个结晶区以及5条单变量曲线组成,有复盐溢晶石（2MgCl₂·CaCl₂·12H₂O）生成,为复杂四元体系。4个结晶区分别对应3个单盐结晶区MgCl₂·6H₂O、CaCl₂·6H₂O、AlCl₃·6H₂O和1个复盐结晶区2MgCl₂·CaCl₂·12H₂O,结晶区按照AlCl₃·6H₂O、MgCl₂·6H₂O、CaCl₂·6H₂O、2MgCl₂·CaCl₂·12H₂O顺序依次减小,对应AlCl₃·6H₂O溶解度最小,2MgCl₂·CaCl₂·12H₂O溶解度最大。      

氯化钙对三水碳酸镁晶体结晶过程的影响

以菱镁矿煅烧所得活性氧化镁为原料,氯化钙为添加剂,采用热分解法制备了MgCO₃·3H₂O晶体,主要研究添加剂种类、氯化钙用量及热解时间对结晶过程的影响,并分析氯化钙的作用机理。借助X射线衍射（XRD）和扫描电镜（SEM）表征产物的物相结构和微观形貌。结果表明,氯化钙用量为5.0 g/L时,获得表面长着球状颗粒、平均长度45 μm、长径比15的棒状MgCO₃·3H₂O晶体。氯化钙对MgCO₃·3H₂O晶体的定向生长无调控作用,主要通过静电吸附的方式参与MgCO₃·3H₂O晶体的结晶过程,其作用下,诱导期延长,成核速率减缓,生长速率增大。      

热分解法制备三水碳酸镁晶须及其结晶动力学研究

利用菱镁矿制备重镁水溶液,以此为前驱溶液,采用热分解法制备三水碳酸镁晶须。借助X射线衍射分析（XRD）和扫描电镜（SEM）探究热解时间、重镁水溶液浓度和搅拌速率对产物组成和形貌的影响,并研究结晶动力学。结果表明,在温度50 ℃、热解时间120 min、重镁水质量浓度为2.75~3.39 g/L时,热分解法制备得到平均直径为6.0 μm、平均长度为100 μm的棒状MgCO₃·3H₂O晶须。随着时间和浓度增加,MgCO₃·3H₂O晶体表面或整个棒状结构会发生溶解重新形成无定形颗粒,并逐渐形成多孔棒状4MgCO₃·Mg（OH）₂·3H₂O。搅拌速率影响MgCO₃·3H₂O晶须的产率。MgCO₃·3H₂O晶体中,[MgO₆]正八面体通过Mg-O键以共顶点的方式紧密相连,沿化学键作用力较强的[010]方向无限连接形成长链。结晶动力学线性拟合结果表明重镁水溶液浓度增大,诱导期时间缩短。      

磷酸盐基新型激光隐身智能材料的性能研究

为提升飞行器的抗激光损伤性能,本试验开展基于相变原理的智能化高能激光防护材料研发。基于Sm对1 050～1 150 nm波段红外光的吸收,利用沉淀法制备了Sm PO₄?n H₂O水磷钐石,重点研究了Sm PO₄?n H₂O及其热相变产物在1 064 nm波长的激光隐身与防护特性。结果表明,水热合成14 d制备的Sm PO₄?n H₂O具有较好的激光隐身性能,其在约1 080 nm波段的反射率为43.8%;1～7 d合成Sm PO₄?n H₂O的晶粒团聚严重,影响细小晶粒吸收截面比。Sm PO₄·0.667H₂O具有良好的脱水吸附可逆性和结构稳定性,其在250℃左右完全脱水,842℃左右转变为热障涂层用的Sm PO₄独居石;Sm PO₄独居石在1 064 nm处的反射率为70.9%,表明Sm PO₄?n H...     

硅镁型红土镍矿脱羟基相变过程动力学研究

镍具有优良的物理化学性质,应用领域广泛,镍资源主要存在于硫化镍矿和红土镍矿中,目前红土镍矿正逐渐成为主要的镍提取原料,由于红土镍矿含水量大,在冶炼过程中通常要对矿石进行高温预处理,目的是为了去除矿石晶格里的羟基水以及预先还原部分金属,但这部分羟基水的脱除需要消耗大量能量,并且产生物相变化,对预还原及浸出都会产生影响,因此探究红土镍矿脱羟基过程的物相变化及动力学条件对后续加工作业具有重要的研究意义。本文利用热力学分析软件模拟计算了红土镍矿加热过程中可能发生的化学反应,并采用热重-差热分析及 XRD 分析研究了硅镁型红土镍矿加热过程的物相变化,从室温到1400°C范围内进行了5种升温速率的非等温动力学实验,在256.8°C、582.8°C和823.0°C 处有三个特征峰,分别对应褐铁矿脱羟基、蛇纹石脱羟基以及硅酸盐矿物的相变。采用非等温动力学模型求解来确定反应的表观活化能及指前因子,使用Flynn-Wall-Ozawa 法和Kissinger-Akahira-Sunose 法计算了蛇纹石脱羟基过程的活化能,并利用Satava-Sestak法对常用的30种机理函数进行拟合,保留符合条件的机理函数,确定 Avrami-Erofeev 方程的A1/3函数符合脱羟基过程,其积分形式为G(α)= [-ln(1-α)]3,求得蛇纹石脱羟基反应的活化能为258.71 kJ·mol-1, lnA为28.94 S-1,平均线性相关系数为 0.9951,蛇纹石脱羟基过程符合随机成核及随后生长模型。     

红土镍矿盐酸浸出工艺及矿物溶解机理研究

在热力学理论分析基础上, 常压下采用盐酸浸出红土镍矿中镍、钴等有价金属, 探讨了有价金属溶出机理。结果表明;初始盐酸浓度8 mol/L, 浸出温度360 K, 固液比1∶4, 反应时间2 h, 镍、钴、锰浸出率分别达到94%, 61%和96%, 此时铁、镁浸出率为56%和94%。根据热力学计算和浸出机理分析可知, 红土镍矿在常压盐酸浸出过程中, 各主要矿相溶解先后顺序是;针铁矿>蛇纹石>磁铁矿>赤铁矿。     

Propanetricarboxylic acid ornamented multi-CeⅢ encapsulated phospho(Ⅲ) tungstate and its electrochemical sensing properties

A propanetricarboxylic acid ornamented multi-Ce^Ⅲ encapsulated phospho(Ⅲ)tungstate [H₂N(CH₃)₂]₄Na₄H₂[Ce₄(HP)W₄(H₂0)₁₄(H₂PTCA)₂O₁₈][(HP^Ⅲ)₂W₂₂O₇₆]·16H₂O(1,H3PTCA=1,2,3-propanetricarboxylic acid) was obtained by a facile one-step reaction of Na₂WO₄·2H₂O,H_3<...     

红土镍矿酸浸废水中铁镁分离与回收利用

以红土镍矿酸浸产生的废水为原料,采用氧化-中和水解法沉淀铁,氢氧化钙沉淀法沉镁制备无机填料,为红土镍矿酸浸废水中有价金属的回收利用提供依据。研究了沉铁过程中温度和反应终点pH值对沉铁率及镁损失率的影响,获得适宜的沉铁条件为:温度40 ℃、pH=4.0,此时沉铁率可达99.86%,镁损失率约为2%。同时研究了沉镁过程中反应时间、反应温度、搅拌速度、镁钙摩尔比对镁沉淀率和钙利用率的影响,结果表明:温度50 ℃、搅拌速度300 r/min、反应时间2 h、镁钙摩尔比1∶1.2时,沉镁率可达99.53%,钙利用率为96.46%。采用XRD和SEM分析了沉镁产物的组成和结构,表明其为[Mg(OH)₂-CaSO₄·2H₂O]混合物,可用作无机填料。     

MgO/Al2O3质量比对褐铁矿型红土镍矿烧结成矿行为的影响

为了提高红土镍矿烧结矿的产质量指标,基于热力学分析,查明了MgO/Al₂O₃质量比对高温烧结过程液相量及其黏度的影响;再通过微型烧结试验探讨了镁/铝质量比对烧结矿的物相组成、黏结相强度的影响,阐明其对褐铁矿型红土镍矿烧结成矿行为的影响;最后通过烧结杯烧结扩大试验进行了有效性验证。微型烧结试验结果表明,在烧结温度为1 300℃、烧结气氛为5%CO+95%N₂、二元碱度m(CaO)/m(SiO₂)=1.3的条件下,m(MgO)/m(Al₂O₃)=0.5～0.8范围内,黏结相主要由钙镁黄长石和钙镁橄榄石构成,强度超过4 000N/个。烧结杯验证试验表明,镁/铝质量比由0.5提高至0.7时,烧结矿的成品率无明显变化保持在70%左右,但是其转鼓强度由49.73%提高至56.67%,烧结矿的转鼓强度得到有效改善,适宜的镁/铝质量比为0.6～0.7。     

纳米Mn3O4的快速制备及其对亚甲基蓝的类芬顿催化氧化性能

采用氧化沉淀法,以Mn(NO₃)₂·H₂O为锰源、NH₃·H₂O为沉淀剂、H₂O₂为氧化剂,在温和条件下反应1 h制备了粒度均匀的纯相纳米Mn₃O₄。以亚甲基蓝溶液为模拟染料废水,考察了纳米Mn₃O对亚甲基蓝的类芬顿催化氧化效果。结果表明,当Mn₃O₄加入量为0.5 g/L时,对25 mg/L亚甲基蓝的降解率可达80.3%。     

Study of phase transformation of laterite ores at high temperature

The phase transformation of laterite minerals reduced at temperatures up to 800 °C and the phase reversibility with cooling were investigated in this study. The phases were studied by in situ synchrotron radiation based X-ray powder diffraction with temperature resolved studies. The degrees of reduction were confirmed by a leaching of reduced ore with ammoniacal solution. Key features, which were observed in this study, include the role of dehydroxylation in releasing nickel and cobalt from the main gangue minerals in which these metals are incorporated. The transformation of hydrated gangue, goethite in limonite to magnetite and the serpentine minerals to the olivine phases in the saprolite and control of these phase transformations, in particular the recrystallisation of magnesium silicate to the forsterite phase were also investigated.     

贵州某红土型锐钛矿化学选矿预富集试验

贵州织金某矿区红土型锐钛矿石TiO_2含量为7.55%,主要钛矿物为锐钛矿,主要脉石矿物为石英、针铁矿、高岭石和海泡石,属难选锐钛矿石。根据矿石性质的特点,对矿石进行了加碱焙烧—酸浸试验。结果表明:在氢氧化钠用量为700 kg/t,焙烧温度为450℃,焙烧时间为35 min,盐酸用量为200 kg/t,盐酸浸出时间为12 min条件下,获得的锐钛矿精矿TiO_2品位为28.89%、TiO_2回收率为86.75%,较好地实现了钛的预富集。焙砂水浸滤液中的大量偏铝酸钠、硅酸钠分别可用来生产纳米氢氧化铝和水玻璃。     

某高镁低铁镍型红土镍矿石转底炉法还原提镍试验

某高镁低铁镍型红土镍矿石Fe、Ni品位分别为17.68%和1.62%，MgO含量为19.06%，镍主要以类质同象形式取代Fe、Mg存在于铁氧化物和硅酸盐矿物中，占比分别为39.65%和54.72%。为了确定该矿石的高效开发利用工艺，通过小型基础试验确定还原焙烧和磨选工艺参数，再在中径8 m的转底炉上进行还原焙烧中试试验。结果表明：试样采用煤基直接还原-水淬冷却-2阶段磨矿弱磁选工艺处理，在红土镍矿、石灰石、TN的质量配比为100∶10∶3，按碳氧物质的量之比1.2配入无烟煤，还原焙烧温度为1 280 ℃，还原焙烧时间为40 min，还原焙烧熟料水淬产品一段磨矿细度为-0.074 mm占83.31%，一段弱磁选磁场强度为190.98 kA/m，二段磨矿细度为-0.074 mm占97.43%，二段弱磁选磁场强度为127.32 kA/m的情况下，获得了Ni品位为5.63%、Fe品位为60.39%、Ni回收率为80.83%、Fe回收率为75.14%的镍铁粉；中径8 m的转底炉中试产品经磨选，获得了Ni品位为5.26%、Fe品位为59.20%、Ni回收率为80.84%、Fe回收率为74.98%的镍铁粉。该研究成果可作为工程化的依据，也为同类型红土镍矿石资源的高效开发利用提供了技术借鉴。     

Kinetics of saprolitic laterite leaching by sulphuric acid at atmospheric pressure

Mineralogical analyses of the saprolitic laterite material have been characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermal analysis, scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX). Results showed that the saprolitic laterite material consists mainly of nickel-substituted lizardite showing the pebble-like morphology and traces of magnetite and phlogopite. Leaching results showed that as much as 84.8% nickel could be leached under the experimental conditions of 10% (v/v) H₂SO₄, 90 °C reaction temperature, leached within 5 min, particle size d₅₀ = 25 μm, stirring at 500 rpm and liquid to solid ratio 3:1. The kinetics of nickel and magnesium leaching from the saprolitic laterite material have been investigated in a mechanically stirred reactor and the activation energies were determined to be 53.9 kJ mol^?1 for nickel and 59.4 kJ mol^?1 for magnesium respectively, which are characteristic for a chemical reaction controlled process. The similarity of the activation energies of nickel and magnesium leaching from the saprolitic laterite material by sulphuric acid means that nickel in lizardite is loosely bound within the octahedral layer and almost all of the nickel could be leached simultaneously with magnesium but without complete decomposition of the silicate structure.     

缅甸莫苇塘镍矿区地质填图总结及成矿分析

文中通过两期在缅甸莫苇塘镍矿区野外地质填图的实践与探索,在对镍矿区地质填图工作总结的基础上根据所获取的认识对镍矿的矿床成因进行了较深入的分析与探讨,并结合两期报告综合研究的成果,作出矿床成因类型为"原生含镍超基性岩在表生风化作用下红土化过程中形成的硅酸盐镍矿床"的结论。     

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.     

Leaching of limonitic laterite ore by acidic thiosulfate solution

Cobalt is usually recovered as a by-product of copper and nickel processing, and only a small amount of cobalt is derived from laterites although a vast majority of cobalt resources in them. The exploitation of limonitic laterite containing high content of cobalt is becoming increasingly important. The mineralogy of a limonitic laterite ore was characterized by environmental scanning electron microscope (ESEM) and X-ray diffraction (XRD) in this paper. The results show that nickel occurs in goethite mainly, while cobalt is predominantly associated with manganiferous minerals. Thiosulfate is found to be able to selectively leach cobalt from limonitic laterite in the presence of sulfuric acid, and 91% Co, 22% Ni, 10% Fe are leached from an ore containing 0.13% Co, 1.03% Ni within the first 5 min at 90 °C under the conditions of 10 g/L sodium thiosulfate, 8% (w/w) sulfuric acid and 10:1 L/S ratio. The leaching kinetics of Mn and Co by acidic sodium thiosulfate solution can be characterized by the Avrami equation. In acidic solution, thiosulfate readily decomposes into sulfur and sulfur dioxide as intermediary reagents to reduce pyrolusite (MnO₂) and goethite (FeOOH); therefore, nickel and cobalt associated with goethite and pyrolusite respectively are extracted due to reduction dissolution. Furthermore, cobalt is selectively leached over iron and nickel because pyrolusite is preferentially reduced by acidic thiosulfate rather than goethite. The novel process may give an alternative method to selectively recover cobalt as the primary product from limonitic laterites at atmospheric pressure.     

Microwave heating behaviour of nickeliferous limonitic laterite ores

The nickeliferous laterite ores, in which the nickel occurs in oxide form, represent a significant potential resource of metallic nickel. However, in comparison to the nickel-containing sulfide ores, the extraction costs are relatively high and thus it will be necessary to develop new processing techniques, which are both technically and economically viable. In the present research, the potential application of microwaves for the heating of a nickeliferous limonitic laterite ore ((Fe,Ni)O(OH) · nH₂O) was investigated. Firstly, since the nickeliferous limonitic laterite ore contains considerable moisture, both free and combined, then thermogravimetric analysis (TGA) was performed in order to characterize the changes, which result from the dehydration processes. Derivative thermogravimetric analysis (DTGA) curves were calculated from the TGA data. Secondly, the real (ε^′) and imaginary (ε^″) permittivities of the ore were measured at frequencies of 912 and 2460 MHz at temperatures up to about 1000 °C using the cavity perturbation technique and these results were related to the DTGA curves. Also, the loss tangent (tanδ=ε^″/ε^′) was calculated from the permittivity data. Finally, the microwave heating behaviour of the nickeliferous limonitic laterite ore was determined at 2460 MHz.The results show that the both the real (ε^′) and imaginary permittivities (ε^″) and the loss tangent (tanδ) increase with temperature and change as both the free and the combined moisture are removed. The permittivities (ε^′ and ε^″) increased with increasing slope of the TGA curve and vice versa during the goethite to hematite dehydroxylation reaction, where there was a maximum in the permittivities (ε^′ and ε^″). It is proposed that these changes, which occur during the dehydroxylation reaction, are a result of the liberation of hydroxyl units from the goethite structure. Furthermore, some hydroxyl units were retained in the hematite structure (i.e. hydrohematite (α-Fe_2−x/3O_3−xOH_x)) even after the goethite to hematite transition and thus the permittivities of the dehydroxylated ore were higher than that of normal hematite. With regards, to their microwave heating behaviour, it is shown that despite the relatively low permittivities (ε^′ and ε^″) of these materials at low temperatures, they can be heated using microwaves. The microwave heating process can be improved by conventional preheating of the sample or by the addition of charcoal as a susceptor or by selecting a crucible material, which acts as a susceptor. There is a rapid increase in the permittivities over the temperature range of about 600–800 °C and this combined with the low thermal conductivities of these oxides, can result in rapid internal heating of the sample and thermal runaway.     

印度尼西亚某红土镍矿还原焙烧-磁选试验

印度尼西亚某低品位红土镍矿含镍1.57%、含铁21.67%,其中镍主要以硅酸镍形式存在。为将该矿石的镍含量提高到6%以上以符合印度尼西亚政府对出口红土镍矿的规定,以硫酸钠和碳酸钠为助熔剂,进行了还原焙烧-弱磁选试验。试验结果表明,当煤用量为25%、硫酸钠+碳酸钠的配比和总用量分别为3∶1和20%、焙烧温度为1 200 ℃、焙烧时间为60 min、磨矿细度为-0.074 mm占85%、磁场强度为96 kA/m时,可获得产率为22.06%、镍品位为6.05%、镍回收率为85.03%、铁品位为65.74%、铁回收率为66.92%的镍铁精矿,其镍品位超过印度尼西亚出口红土镍矿的品位下限。