Gui Fang Wang

Alkaline Leaching of Low Grade Complex Zinc Oxide Ore

Alkaline leaching is an important way for treating low grade metal oxide ore, which has some advantages such as low corrosion and low pollution compared to acidic leaching. In order to recover the zinc from a low grade complex zinc oxide ore in which the grade of Zn and Fe are 13 wt.% and 40.2 wt.%, respectively, and 52.8% of Zn is contained in siderite, 34.63% in limonite and 11.55% in smithsonite, this paper presents a preliminary investigation of this type of ore by alkaline leaching method. In this study, ammonia-ammonium chloride and ammonia-ammonium carbonate were used as the leaching reagents. The effects of alkaline concentration, leaching time, leaching temperature and liquid to solid ratio (L/S) were studied, respectively. The results show that 43.15% of initial Zn content was extracted adopting ammonia-ammonium chloride as the leaching reagent in 4.5M at 30°C for 3h with a liquid to solid ratio of 4:1, while 43.07% of Zn recovery was achieved employing ammonia-ammonium carbonate as the leaching reagent at 5M, 30°C and 4:1(L/S). The low leaching rate of Zn is probably attributed to that the zinc contained in siderite was not extracted completely because Zn and Fe exist as isomorphism in siderite.

Hydrometallurgical Treatment of Low Grade Zinc Oxide Ore

In this research, a leaching study was carried out to assess the effect of several parameters on zinc extraction in a low grade complex zinc oxide ore in which the grade of Zn is 13 wt.%, and 52.8% of Zn is contained in siderite, 34.63% in limonite and 11.55% in smithsonite. The influencing parameters investigated include sulfuric acid concentration, reaction temperature, reaction time and liquid to solid ratio (L/S). The results show that over 90% of Zn can be extracted from the low grade complex zinc oxide ore when the leaching process is operated in 2M sulfuric acid at 60°C for 2.5h with a liquid to solid ratio of 6:1.

Sulfuric Acid Leaching on Low Grade Oxide Ore

In this paper, sulfuric acid leaching was carried out to assess the effect of several parameters on metal extraction in a low grade complex gossan ore in which the grade of zinc and iron is 13% and 40.2%, respectively. Parameters, such as sulfuric acid concentration, liquid to solid ratio and leaching temperature, were studied. The results show that the zinc leaching rate is almost 80%, while the iron leaching rate is about 45% used strong acid with 200g/L. It can be seen from the results that sulfuric acid leaching could not effectively recover zinc from gossan ores studied in this paper because of iron dissolving greatly.

The Preliminary Investigation of Low Grade Zinc Oxide Ore

Flotation is a conventional way for treating low grade metal oxide ore which has some advantages such as high efficiency and low cost. In order to recover the zinc from a low grade complex zinc oxide ore in which the grade of Zn is 13 wt.%, this paper presents a preliminary investigation of this type of ore by flotation method. In the experiments, the effects of different parameters such as grinding fineness, amount of Na2SiO3, amount of Na2S and amount of octadecylamine were investigated in relation to the metal contents of concentrates. The results show that about 35% of initial Zn content was obtained with 70% -200 mesh grinding fineness, 1000g/t Na2SiO3, 2000g/t Na2S and 500g/t octadecylamine. It is clear that the preliminary flotation tests with the ore sample indicated that there was no selectivity in terms of zinc recovery. Almost 65% zinc remained in the tailings and could not be recovered by flotation due to its complicated mineralogical structure. Therefore, application of metallurgical processes is proposed for zinc recovery from the tailings in the following investigations.

Study on Porous Structure and Surface Characteristics of Al-Pillared Montmorillonite

Al-pillared montmorillonite (Al-PILM) prepared with Keggin ions was studied by means of XRD, SEM-EDS and N2 adsorption-desorption isotherms.The rusults show that, compared to unpillared Na-montmorillonite (Na-M), the interlayer spacing d(001) value, BET specific surface area, surface fractal dimension and the proportion of microporous specific surface area of Al-PILM are larger and the surface is relatively rough. The BJH porous volume distribution of Al-PILM is the most probable distribution, and the most probable pore size is about 2 nm, belonging to mesopore. The porous structure of Al-PILM is characterized as parallel plate slit or “house-of-cards” wedge-shaped pore which is formed by novel meso-microporous delaminated structure and fragments. Besides, the results of elemental distribution show that the ions exchange action between Na+ and hydroxy-Al cations in pillaring solution occurs in the formation of Al-PILM.

Study on Microstructure Variation Laws of Al-Pillared Montmorillonite

Al3+/clay ratio is one of the important factors influencing microstructure of Al-pillared montmorillonite. Microstructure variation laws of Al-pillared montmorillonite prepared under the condition of different Al3+/clay ratio are systematically studied by XRD, FTIR, specific surface area and pore size analysis. The results show that the interlayer spacing and BET specific surface area of Al-pillared montmorillonite are remarkably affected by the Al3+/clay ratio. The interlayer spacing d(001) value and BET specific surface area of Al-pillared montmorillonite increase firstly and then decrease with the increases of the Al3+/clay ratio, and they reach to maximum when the Al3+/clay ratio is 10mmol/g. Besides, the BJH porous volume distribution of Al-pillared montmorillonite is the most probable distribution, and the most probable pore size is about 2 nm, which is attributed to mesopore. The porous structure of hydroxy-Al pillared montmorillonite is characterized as parallel plate slit or “house-of-cards” wedge-shaped pore which is formed by novel meso-microporous delaminated structure and fragments. With the increase of the Al3+/clay ratio, BJH total porous volume and mesoporous volume of hydroxy-Al pillared montmorillonite decreases, while the proportion of microporous volume in the total porous volume increases. The proportion of microporous specific surface area of all the hydroxy-Al pillared montmorillonite samples is about 62% and is much larger than that of Na-M and those of mesopore and macropore, indicating the main action of intercalation of hydroxy-Al pillaring solution into montmorillonite interlayer is to increase the micropore amount.

Study on Recovering Zinc from Gossan

In this paper, the conventional physical separation method such as flotation, gravity separation, magnetic separation, alkaline leaching and sulfuric acid leaching were studied. The effects of grinding fineness, amount of agent, magnetic intensity, roasting temperature, roasting time, the leaching agent and leaching time on the leaching of zinc were investigated, respectively. The results show that the leaching rate of zinc is below 50% in the conventional alkaline leaching, and the leaching rate of zinc is below 85% and the leaching rate of iron is above 35% in sulfuric acid leaching. Compared with XRD pattern of the raw ore, the different diffraction peaks of smithsonite is off in alkaline leaching products. In sulfuric acid leaching, the different diffraction peaks of smithsonite are off in the leaching products when sulfuric acid concentration is less than 60 g/L. After 60 g/L, the different diffraction peaks of smithsonite and siderite are off in the leaching products.

Study on Preparation Process of Zinc Ferrite

Zinc ferrite is usually formed during the roasting of zinc sulfide concentrate with high content of iron and reduces zinc recovery during the leaching of zinc calcine. Because it is difficult to find pure zinc ferrite in nature ore resources or in chemicals market, which impedes the investigation of the reaction characteristics of zinc ferrite and the seek of new technologies for zinc ferrite dissolution, so it is of significance to obtain relatively pure zinc ferrite for further research on zinc calcine leaching. This article investigated the preparation process of zinc ferrite based on the dissolution characteristics of a zinc calcine with 19.38% iron and put forward a method to judge the reaction end point during the leaching of zinc calcine to produce zinc ferrite. The results show that the product of zinc ferrite could be prepared through recovering the leaching residue during leaching the zinc calcine under the initial H2SO4 concentration equal to or larger than 160g/L, and that the leaching end point can be judged by comparing the experimental curve of Zn leaching with the zinc theoretical dissolvability curve.

The Stability Research of Montmorillonite/Octadecyl Trimethyl Ammonium Complexes

In order to study the stability of Montmorillonite / Octadecyl trimethyl ammonium complexes in engineering application, the influences of the organic modifier dosage, oscillation intensity, oscillation time, temperature, pH, sodium salt concentration, calcium salt concentration on the stability of Montmorillonite / Octadecyl trimethyl ammonium complexes were systematically investigated. Research results show that the stability of Montmorillonite / Octadecyl trimethyl ammonium complexes slightly reduces with the increases of oscillation intensity, oscillation time and temperature, but the impact isn’t obvious. The more the organic modifier dosage is, the more unstable the Montmorillonite / Octadecyl trimethyl ammonium complexes are. The stability of the Montmorillonite / Octadecyl trimethyl ammonium complexes decreases significantly under the medium conditions of lower or higher pH. The higher the concentration of sodium salts is, the more stable the Montmorillonite / Octadecyl trimethyl ammonium complexes are, but calcium salts are on the contrary.

Preparation and Application Performance Study of High Purity Montmorillonite

In order to research the colloidal and thixotropic performance of the inorganic gel prepared by high purity montmorillonite, this study uses the moderate grade bentonite ores from Weifang (China) as raw material. Two-stage hydrocyclone classification was applied to obtain the high purity montmorillonite with its content of 94.8 per cent. In contrast to other methods of montmorillonite purification, two-stage purification by hydroclone has the advantages of larger throughput and easily achieving auto-control in industry, and products with different montmorillonite content can be obtained by this method. And then the inorganic gel was prepared by the prepared high purity montmorillonite , its colloidal and thixotropic performances were further studies. Research results show that the inorganic gel belongs to plastic body liquidity, the viscosity decreases with the increase of the shear rate, the static and dynamic shearing stress values are 33.98 Pa and 91.89 Pa respectively, and the thixotropic value is 95.2 dyne·s/cm2, which indicates that it has preferable colloidal and thixotropic performance. Montmorillonite inorganic gel prepared by bentonite with high montmorillonite content and low- layer charge has better gel performance. The application result of inorganic gel in dentifrice and medicine shows that it has excellent effect.