Bioleaching of pyrite by A. ferrooxidans and L. ferriphilum

Pyrite oxidation rates were examined under various conditions in the presence of A.ferrooxidans and L.ferriphilum,in which different pulp concentration,inoculation amount,external addition of Fe3+ and initial pH value were performed.It is found that A.ferrooxidans and L.ferriphilum show similar behaviors in the bioleaching process.The increasing pulp concentration decreases the leaching rate of iron,and external addition of high concentration Fe3+ is also adverse to leaching pyrite.The increased inoculation amount and high initial pH value are beneficial to leaching pyrite,and these changed conditions bring more obvious effects on leaching pyrite by L.ferriphilum than by A.ferrooxidans.The results also show that adjusting the pH values in leaching process baffles leaching pyrite due to the formed jarosite.Jarosite formed in leaching process was observed using XRD,SEM and energy spectrum analysis,and a considerable amount of debris with a crystalline morphology is present on the surface of pyrite.The results imply that the indirect action is more important for bioleaching pyrite.     

响应曲面法优化氨法焙烧后粉煤灰除铁工艺

通过响应曲面法(RSM)对粉煤灰与硫酸铵焙烧产物的浸出液进行除铁工艺参数的优化.以反应温度、溶液pH值和晶种加入量为变量，反应后溶液中铝离子质量浓度和铁离子质量浓度为相应变量，分别对黄铵铁矾法除铁过程和针铁矿法除铁过程建立相应的数学模型，并对影响因素进行了分析.通过实验对模型进行了检验，其误差在5%以内，表明模型具有一定的可靠性.对模型进行求解后，分别得出黄铵铁矾法除铁和针铁矿法除铁最佳工艺条件.     

黄钠铁矾法氧化去除废锂电池硫酸浸出液中的铁

废锂电池中含有的Co、Ni和Cu等金属具有回收价值,Fe的存在降低了有价金属的回收效率。为去除废锂电池硫酸浸出液中的Fe,采用黄钠铁矾法分别以氯酸钠和过氧化氢作为氧化剂氧化除Fe,并优化了过氧化氢作为氧化剂的除Fe工艺参数。实验结果表明:过氧化氢作为氧化剂的除Fe效果好于氯酸钠;在n(H2O2)∶n(Fe)=0.5、初始溶液pH为1.8、终点pH为2.5、反应时间为2.0 h、搅拌速率为500 r/min的最佳工艺条件下,初始ρ(Fe)为0.212g/L的硫酸浸出液经除Fe处理后ρ(Fe)小于0.004 g/L,Fe去除率达98.0%,Co、Ni和Cu的损失率分别为1.04%、2.17%和1.41%。     

风化矿物黄钾铁矾40Ar/39Ar 测年的基本方法——从样品采集到年龄测试

由于40Ar/39Ar定年方法在技术上极具复杂性,目前,国内在开展干旱区研究中很少使用风化矿物定年研究手段。重点介绍黄钾铁矾矿物40Ar/39Ar定年法的基本流程,并针对该方法的技术问题初步探讨了解决办法。研究表明,科学的野外采集样品、仔细的挑选矿物并综合采用多种测试手段（X衍射、扫描电镜、电子探针）进行监测可以获得纯净的风化矿物,并结合精细的40Ar/39Ar阶段加热技术,能够获得比较可靠的风化矿物40Ar/39Ar年龄。     

Kinetics of alkaline decomposition and cyanidation of argentian ammonium jarosite in lime medium

The alkaline decomposition of argentian ammonium jarosite in lime medium is characterized by an induction period and a conversion period in which the sulfate and ammonium ions pass to the solution whereas calcium is incorporated in the residue jointly with iron; this residue is amorphous in nature. The process is chemically controlled and the order of reaction with respect to the hydroxide concentration is 0.4; the activation energy is 70 kJ mol⁻¹. Cyanidation of argentian ammonium jarosite in lime medium presents the same reaction rate in the range of 0–10.2 mol m⁻³ CN⁻; in this range of concentration, the cyanide process can be described, as in other jarosites, in a two-step process: a step of alkaline decomposition that controls the overall process followed by a fast step of silver complexation. For higher cyanide concentration, the order of reaction with respect to cyanide is 0.65, and kinetic models of control by chemical reaction and diffusion control through the products layer both fit well; the activation energy obtained is 29 kJ mol⁻¹; this is indicative of a mixed control of the cyanidation process in the experimental conditions employed. The process is faster than was observed in ammonium jarosite generated in zinc hydrometallurgy (Industrial Minera México, San Luís Potosí, México); it seems that the reaction rate decreases when the substitution level in the jarosite lattice increases; this behavior is similar to that observed for synthetic potassium jarosite and arsenical potassium jarosite from gossan ores (Rio Tinto, Spain) presented in a previous paper.     

Thermal decomposition of jarosites of potassium,sodium and lead

Summary Jarosites are a group of minerals formed in evaporite deposits and form a component of efflorescence. As such the minerals can function as cation and heavy metal collectors. Thermogravimetry coupled to mass spectrometry has been used to study three Australian jarosites which are predominantly K, Na and Pb jarosites. Mass loss steps of K-jarosite occur over the 130 to 330 and 500 to 622°C temperature range and are attributed to dehydroxylation and desulphation. In contrast the behaviour of the thermal decomposition of Na-jarosite shows three mass loss steps at 215 to 230, 316 to 352 and 555 to 595°C. The first mass loss step for Na-jarosite is attributed to deprotonation. For Pb-jarosite two mass loss steps associated with dehydroxylation are observed at 390 and 418°C and a third mass loss step at 531°C is attributed to the loss of SO₃. Thermal analysis is an excellent technique for the study of jarosites. The analysis depends heavily on the actual composition of the jarosite.     

Bacterial oxidation of ferrous iron at low temperatures

This study comprises the first report of ferrous iron oxidation by psychrotolerant, acidophilic iron-oxidizing bacteria capable of growing at 5 degrees C. Samples of mine drainage-impacted surface soils and sediments from the Norilsk mining region (Taimyr, Siberia) and Kristineberg (Skellefte district, Sweden) were inoculated into acidic ferrous sulfate media and incubated at 5 degrees C. Iron oxidation was preceded by an approximately 3-month lag period that was reduced in subsequent cultures. Three enrichment cultures were chosen for further work and one culture designated as isolate SS3 was purified by colony isolation from a Norilsk enrichment culture for determining the kinetics of iron oxidation. The 16S rRNA based phylogeny of SS3 and two other psychrotolerant cultures, SS5 from Norilsk and SK5 from Northern Sweden, was determined. Comparative analysis of amplified 16S rRNA gene sequences showed that the psychrotolerant cultures aligned within Acidithiobacillus ferrooxidans. The rate constant of iron oxidation by growing cultures of SS3 was in the range of 0.0162-0.0104 h(-1) depending on the initial pH. The oxidation kinetics followed an exponential pattern, consistent with a first order rate expression. Parallel iron oxidation by a mesophilic reference culture of Acidithiobacillus ferrooxidans was extremely slow and linear. Precipitates harvested from the 5 degrees C culture were identified by X-ray diffraction as mixtures of schwertmannite (ideal formula Fe(8)O(8)(OH)(6)SO(4)) and jarosite (KFe(3)(SO(4))(2)(OH)(6)). Jarosite was much more dominant in precipitates produced at 30 degrees C.     

黄钾铁矾固溶物的制备及拉曼光谱分析

利用水热法实验制备黄钾铁矾固溶系列样品AFe_3(SO_4)_2(OH)_6,其中A位置可以被K~+、Na~+和H_3O~+占据。此外,还制备近全钾占据的黄钾铁矾作为对比样品。对制备的黄钾铁矾群样品进行了拉曼光谱测试,黄钾铁矾的拉曼光谱分为羟基区(3000~4000cm~(-1))、硫酸根内部模式、点阵振动模三个主要部分,并对有异议的振动模的归属重新做了分析。利用拉曼光谱峰的数目以及频移,离子半径的大小、键长、键角的变化等信息,采用胡克定律分析了黄钾铁矾固溶系列A位置的离子替换作用。A位置离子的替换作用主要影响黄钾铁矾结构中OH基周围的环境,使得与羟基相关的振动模发生变化。     

从黄钾铁矾渣中回收锌铟

由黄钾铁矾渣在焙解过程的化学变化，确定回收锌铟的适宜焙解温度为４２１．５～６７０℃。实验表明黄钾铁矾渣中铁酸锌转化为可溶硫酸锌的转化率随焙解温度升高而增加，可浸出的铟由焙解温度和时间决定。当温度为５６０～６２０℃、时间为３０～１０ｍｉｎ时，锌的浸出率为８０％、铟为９０％。     

抑制氧化亚铁硫杆菌作用下沉淀生成的研究

为了减少氧化亚铁硫杆菌培养过程中黄钾铁矾沉淀的生成,通过改变培养基的pH值、菌种的培养温度、不同的菌种接种量及优化培养基组分等方法,确定出黄钾铁矾沉淀生成量最少的培养条件,即培养基pH值为2.0,培养温度为30℃,菌种接种量为10%,最佳培养基组分K2HPO4为0.25 g/L,KH2PO4为0.195 g/L。此条件下即能保持菌种的良好活性,又能使产生沉淀量降至2.27 g/L。