大同煤制备低酸溶铁活性炭的工业中试

对大同烟煤制活性炭进行脱除酸溶铁的中试表明,利用大同煤可生产出酸溶铁低于0 01%的优质煤质活性炭。增加酸洗次数、提高酸炭比、增加酸浓度、延长浸泡时间和提高酸洗温度都是脱铁的有效手段,而降低活性炭的粒度对脱铁最为有效;同时应充分考虑选用低铁含量的工业盐酸和工业用水。

电感耦合等离子体原子发射光谱(ICP-AES)法测定大理石岩型石墨矿中的酸溶铁

试样经过盐酸溶解,过滤后用电感耦合等离子体原子发射光谱(ICP-AES)法测定大理岩型石墨矿中的酸溶铁。实验表明,加标回收率为99.1%,相对标准偏差(RSD)为1.0%,检出限为5μg/g,经过与标准方法分析结果对比,得到了国家标准方法一致的测定结果,但更加适用于批量样品的测定。

低酸溶铁活性炭的工业中试

为了用大同烟煤活性炭生产低酸溶铁质量分数的活性炭,分析了盐酸的浓度、酸洗次数、酸洗时间、酸洗温度、酸炭比及活性炭粒度对降低活性炭酸溶铁质量分数的影响,Cl-多、酸洗次数多、活性炭粒度小、酸炭比值大,均有利于脱铁,同时盐酸浸泡时间宜控制在12h,加热温度在100℃以内。试验证明工业化生产完全可生产出酸溶铁质量分数低于0.03%的优质煤质活性炭。

探伤磁粉中酸溶铁的无污染分析

探伤磁粉中酸溶铁的含量是控制磁粉质量的重要指标之一,探伤磁粉中酸溶铁的测定曾采用SnCl_2-HgCl_2-K_2Cr_2O_7滴定法。由于该方法使用了大量剧毒的汞盐,严重污染环境。为此,提出了在1.5～3.5mol/L硫酸介质中,用硫酸镍作催化剂,次亚磷酸钠还原Fe(Ⅲ),以邻苯氨基苯甲酸为指示剂,硫酸高铈滴定法测定探伤磁粉中酸溶铁的方法。实验证明,此方法冷却后即可滴定,无需消除过量的还原剂,在大量的镍、铜、铬等元素存在情况下不干扰测定。具有操作简便,再现性和准确度较好。

活性炭检测技术介绍

本文详细介绍了活性炭的含氟量的检测及酸溶灰、酸溶铁、磨损强度的检测方法。

Effect of sodium hexametaphosphate on separation of serpentine from pyrite

The effect of sodium hexametaphosphate（SHMP） on the separation of serpentine from pyrite and its mechanism were studied systematically through flotation tests,sedimentation tests,surface dissolution,ζ potential tests,adsorption measurements,and infrared spectroscopic analyses.The results show that the SHMP could significantly reduce the adverse effect of serpentine on the flotation of pyrite and make the mixed sample of pyrite and serpentine more disperse in the alkaline condition,thus improve the adsorption of xanthate on pyrite.The action mechanism of the SHMP is that it lowers the pH value at the isoelectric point of serpentine and enhances the negative charge through the dissolution of magnesium from the surface of serpentine and adsorbing on the surface of serpentine.It changes the total interaction energy between serpentine and pyrite from gravitational potential energy to repulse potential energy,according to the calculation of the EDLVO theory.

Removal of S^(2-) ion from sodium aluminate solutions with sodium ferrite

The synthesis of sodium ferrite and its desulfurization performance in S2 -bearing sodium aluminate solutions were investigated. The thermodynamic analysis shows that the lowest temperature is about 810 K for synthesizing sodium ferrite by roasting the mixture of ferric oxide and sodium carbonate. The results indicate that the formation process of sodium ferrite can be completed at 1173 K for 60 min, meanwhile raising temperature and reducing NazCO3 particle size are beneficial to accelerating the formation of sodium ferrite. Sodium ferrite is an efficient desulfurizer to remove the S2- in aluminate solution, and the desulfurization rate can reach approximately 70% at 373 K for 60 min with the molar ratio of iron to sulfur of 1：1-1.5：1. Furthermore, the desulfurization is achieved by NaFeS2·2H2O precipitation through the reaction of Fe（OH）4 and S^2- in aluminate solution, and the desulfurization efficiency relies on the Fe（OH）4^- generated by dissolving sodium ferrite.

Removal of tungsten from molybdate solution by Fe-Mn binary oxide adsorbent

Considering the different geochemical enrichment behaviors of W and Mo,Fe?Mn binary oxide(FMBO),ferric hydroxide(Fe(OH)3)and manganese dioxide(MnO2)were studied to separate W from molybdate solution,respectively.The experimental results demonstrated that Fe?Mn binary oxide(FMBO)was the most suitable adsorbent for the separation.Under a wide pH(6.9?11.3)region,more than80%W removal efficiency and less than3%Mo loss could be obtained.In addition,the Fe?Mn binary oxide adsorbent can be regenerated by treating with3mol/L NaOH,and the W adsorption efficiency was retained after five adsorption?desorption?regeneration cycles.All these indicate that the Fe?Mn binary oxides have the potential for the separation of W from molybdate solution.

Leaching kinetics of acid-soluble Cr(Ⅵ) from chromite ore processing residue with hydrofluoric acid

Leaching kinetics of acid-soluble Cr（VI） in chromite ore processing residue （COPR） using hydrofluoric （HF） acid solution as a leaching agent was investigated for potential remediation of COPR with industrial waste water containing HF. The results show that HF can effectively destabilize the Cr（VI）-bearing minerals, resulting in the mobilization of Cr（VI） from COPR into the leachate. Particle size significantly influences the leaching of acid-soluble Cr（VI） from COPR, followed by leaching time, whereas the effects of HF concentration and leaching temperature are slight and the influence of stirring rate is negligible. The leaching process of acid-soluble Cr（VI） from COPR is controlled by the diffusion through the product layer. The apparent activation energy is 8.696 kJ/mol and the reaction orders with respect to HF concentration and particle size is 0.493 8 and -2.013 3, respectively.

Bioleaching of pyrrhotite by Sulfobacillus thermosulfidooxidans

The bioleaching of pyrrhotite was investigated using Sulfobacillus thermosulfidooxidans.The effects of pH,pulp concentration,inoculation amount,external addition of ferrous and ferric ions were examined.The pH is found to exert a profound effect on the leaching process for controlling the bacterial activity and precipitation of ferric ions mainly as jarosite.The results show that low pulp content increases the leaching rate of iron.The inoculation amount from 1×107 cell/mL to 1×108 cell/mL has positive effects on the leaching rate.The results also imply that addition of ferrous sulfate(1 g/L) is required for the bacteria to efficiently drive the extraction of iron,however,the leaching efficiency has no obvious enhancement when 2 g/L ferrous sulfate was added.Comparatively,addition of ferric sulfate(2 g/L) significantly inhibits the bioleaching process.At the end of bioleaching,jarosite and sulfur are observed on the surface of pyrrhotite residues by using XRD and SEM.With the passivation film formed by jarosite and sulfur,the continuous iron extraction is effectively blocked.

Reaction behavior of kaolinite with ferric oxide during reduction roasting

The pre-separation of silica and alumina in aluminosilicates is of great significance for efficiently treating alumina-/ silica-bearing minerals for alumina production. In this work, the reaction behavior of kaolinite with ferric oxide during reduction roasting was investigated. The results of thermodynamic analyses and reduction roasting experiments show that ferrous oxide obtained from ferric oxide reduction preferentially reacts with alumina in kaolinite to form hercynite, meanwhile the silica in kaolinite is transformed into quartz solid solution and/or cristobalite solid solution. With increasing roasting temperature, fayalite formed by reaction of surplus ferrous oxide with silica at low temperature is reduced to silica and metallic iron in the presence of sufficient carbon dosage. However, increasing roasting temperature and decreasing Fe2O3/Al2O3 molar ratio favor mullite formation. The complete conversion of kaolinte into free silica and hercynite can be obtained by roasting raw meal of kaolin, ferric oxide and coal powder with Fe2O3/Al2O3/C molar ratio of 1.2:2.0:1.2 at 1373 K for 60 min. This work may facilitate the development of a technique for comprehensively utilizing silica and alumina in aluminosilicates.

Effects of Surfactant on Zinc Recovery by Solvent Extraction during Leaching in HCl-FeCl_3 Solution

The effects of surfactant on the solvent extraction in leachingsphalerite were investigated. It is found that sodium dodecylsulfonate is the effective surfactant in improving the zinc recoveryfrom sphalerite in the aqueous FeCl_3-HCl-tetrachloroethylene system.Through the measurements of surface tension and viscosity of thesphalerite Slurry modified with different surfactants, it isconcluded that sodium dodecyl sulfonate in the concentration rang Of0.05 to 0.2 g·L^-1 can improve the viscosity of sphalerite slurry inthe water, decrease the surface tension of Leaching solution, preventthe aggregation of ore particles, and give very high zinc extraction.

Effects of temperature and phosphoric acid addition on the solubility of iron phosphate dihydrate in aqueous solutions

As important controlling factors for the synthesis of iron phosphate materials by liquid-phase precipitation, the solubilities of iron phosphate dihydrate were systematically measured at H3PO4 concentrations from 1.13 wt% to 10.7 wt% temperature from 298.15 to 363.15 K, and atmosphere pressure in this work. The solubility was found to increase 5 orders of magnitude or more with increasing the concentration of phosphoric acid, and de- crease 1 to 2 orders of magnitude with increasing the equilibrium temperature. The phosphoric acid addition and temperature were found to affect the solubility of iron phosphate dihydrate by the formation or dissociation of coordination species, which could further accelerate the phase transformation from the amorphous iron phosphate dihydrate to orthorhombic iron phosphate dehydrate by dissolution-recrystallization mechanism. The high dependences of the solubility of iron phosphate materials on HsPO4 concentration and temperature were also well predicted by calibration equations, which are meaningful for quantitatively understanding the precipitation process and sequential crystalline structure transformation and pursuing a rational strategy for syn- thesizing specific iron phosphate materials.

Effects of iron-containing phases on transformation of sulfur-bearing ions in sodium aluminate solution

Sulfides in the high-sulfur bauxite lead to serious steel equipment corrosion and alumina product degradation via theBayer process,owing to the reactions of sulfur and iron-containing phases in the sodium aluminate solution.The effects ofiron-containing phases on the transformation of sulfur-bearing ions(S2?,223S O?,23SO?and24SO?)in sodium aluminate solutionwere investigated.Fe,Fe2O3and Fe3O4barely react with23SO?and24SO?,but all of them,particularly Fe,can promote theconversion of223S O?to23SO?and S2?in sodium aluminate solution.Fe can convert to3Fe(OH)?in solution at elevatedtemperatures,and further react with S2?to form FeS2,but Fe2O3and Fe3O4have little influence on the reaction behavior of S2?insodium aluminate solution.Increasing temperature,duration,dosage of Fe,mole ratio of Na2Ok to Al2O3and caustic sodaconcentration are beneficial to the transformation of223S O?to23SO?and S2?.The results may contribute to the development oftechnologies for alleviating the equipment corrosion and reducing caustic consumption during the high-sulfur bauxite treatment bythe Bayer process.

Effects of organic acids on dissolution of Fe and Mn from weathering coal gangue

Understanding the effects of organic acids （OA） on the transformation of Fe and Mn to surface water from the weathering coal gangue is of great benefit to risk assessment and remediation strategies for contaminated water and soil. Based on the investigation on surface water in the central coal districts of the Guizhou Province, 18 water samples were collected for heavy metal analysis. The results indicated that the pH value of surface water is low （3.11-4.92）, and Fe concentration （1.31-5.55 mg L-1） and Mn concentration （1.90-5.71 mg L^-1） were, on average, 10.86 and 34.33 times the limit of Surface Water Quality Standards, respectively. In order to evaluate the effects of the OA on the dissolution of Fe and Mn from the weath- ering coal gangue, column elution and batch leaching experiments were conducted. The results show that the low molecular weight of organic acids （LMWOAs, i.e., oxalic, tartaric, malic and citric acids） and fulvic acids signifi- cantly accelerated the dissolution of Fe and Mn; in addi- tion, when the concentration of OA reached 25 mmol L-1, the concentrations of Fe, and Mn were 1.14-67.08 and 1.11-2.32 times as high as those in 0.5 mmol L-1OA, respectively. Furthermore, the migration of Fe and Mn was significantly influenced by the pH and Eh, especially for Fe; the ion Mn was dissolved from the gangue more easily than the ion Fe in the column leaching, which was contrary to the results of batch leaching.

Effect of iron valence on hydrothermal preparation of pyrochlore-type tungsten oxide

Pyrochlore-type tungsten oxide (PTO), WO3·0.5H2O, is an emerging material with very wide potential applications. The influences of iron valences and the additive amount of ferrous ion on tungsten crystallization ratio and the acceleration mechanism of ferrous ion were investigated when PTO was hydrothermally prepared in aqueous ammonium tungstate solution containing ammonium carbonate. The results show that ferrous ion can remarkably accelerate tungsten crystallization while both elemental iron and ferric ion have little influence on the crystallization. Moreover, the tungsten crystallization ratio increases with increasing the amount of ferrous ions added and reaches the maximum of about 60% with ferrous ion concentration of 16 g/L. FTIR analysis of the spent solution after PTO crystallization shows that ferrous ion can accelerate the conversion of WO4 tetrahedral to WO6 octahedron. Combined with XPS and XRD analyses of the hydrothermal product, the acceleration effect of ferrous ion on tungsten crystallization could basically be attributed to the increase in the interplanar spacing of PTO lattice caused by the incorporation of ferrous ion into PTO crystal lattice. The results presented is conducive to the efficient preparation of PTO powder and cleaner tungsten metallurgy.

Adsorption of 2-naphthalenesulfonic acid/sulfuric acid/sulfurous acid from aqueous solution by iron-impregnated weakly basic resin：Equilibrium and model

Commercial grade weakly basic resin D301 was impregnated with iron through a simple method using ferric chloride. Experiments for single, bisolute and trinary competitive adsorption were carried out to investigate the adsorption behavior of 2-naphthalenesulfonic acid(NSA), sulfuric acid and sulfurous acid from their solution at 298 K onto the novel hybrid iron impregnated D301(Fe-D301). Adsorption affinity of NSA on Fe-D301 was found to be much higher than that of sulfuric acid, while adsorption affinity of sulfuric acid was slightly higher than that of sulfurous acid. The data of single-solute adsorption were fitted to the Langmuir model and the Freundlich adsorption model. The non-ideal competitive adsorbed model coupled with the single-solute adsorption models were used to predict the bisolute and trinary-solute competitive adsorption equilibria. The NICM coupled with the Langmuir model yields the favorable representation of the bisolute and trinary-solute competitive adsorption behavior.

Leaching potential and changes in components of metals in two acidic ferrisols

Two acidic ferrisols, i.e., red soil （RS） and yellow red soil （YRS）, from the vicinity regions of non-ferrous ores in Hunan province of China, were leached with simulated acid rain through artificial column experiments. The results show that the total leaching mass of metals are m（Zn）〉m（Cu）〉m（Cd） from the original soils and m（Cd）〉m（Zn）〉〉 m（Cu） from the contaminated soils with external metals after leaching for 60 d continuously, leaching quantities of Cd and Zn from the contaminated red soil （CRS） are more than that from the contaminated yellow red soil （CYRS）, but for Cu, it is almost the same. The preferential fractions for leaching are mainly in exchangeable forms, and content of exchangeable forms decreases significantly in the contaminated soil profiles. The unstable fractions of Cd, Cu and Zn in the RS and YRS increase significantly with the decrease of pH value of simulated acid rain. Changes of fi, actions of external Cd, Cu, and Zn in the residual CRS and CYRS profiles are significantly affected by the acidity of acid rain, too. After leaching for 60 d continuously, Cd exists mostly in exchangeable form, Cu exists mainly in exchangeable, manganese oxide-occluded and organically bounding forms, and Zn exists in residual in CRS and CYRS profiles. Most of exchangeable Cd and Zn exist only small in surface layer （0-20 cm） and are transferred to the sub-layers, contrarily, Cu accumulates mostly in the topsoil （0-20 cm） with low translocation.

Promotion effect of KOH on preparation of dissolved Fe(Ⅵ)

In order to improve the yield and stability of ferrate in solution, dissolved Fe(Ⅵ) prepared with NaOH and KOH respectively was compared in this study. The results showed that KOH is more suitable than NaOH for the preparation of dissolved Fe(Ⅵ) at temperature over 50 ℃. It is found that the dissolved Fe(Ⅵ) prepared with KOH increases quickly at first, and then slowly with the increasing concentrations of OH-and ClO-, while it increases rapidly at first and then decreases rapidly with the increasing dosage of Fe(NO3)3·9H2O. These results are different from that prepared with NaOH. It can be explained that solid K2FeO4 salts can be formed in KOH solution, and it will lower the Fe(Ⅵ) concentration, counteract the decomposition of Fe(Ⅵ), and improve the yield of Fe(Ⅵ). The maximum ferrate concentration is 0.163 mol/L obtained by 100 g/L Fe(NO3)3·9H2O and 6.16 mol/L KOH at 65 ℃. The stability of Fe(VI) is greatly improved due to the hypochlorite existed in the dissolved ferrate, and only 24% Fe(Ⅵ) has been decomposed after 16 d for 1 mmol/L Fe(Ⅵ) at 25 ℃.