Wei Mo

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.

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.

Experimental Study on Microwave Pretreatment with some Refractory Flotation Gold Concentrate

The microwave pretreatment of a typically refractory flotation gold concentrate was investigated. The results demonstrated that a maximum gold recovery of 97% was achieved, and that gold recoveries of the refractory gold concentrate quickly increased to the maximum with microwave heating time. Adding additives during microwave heating process was helpful to improve the leaching rate of gold, and the effect of microwave heating with single NaOH on the leaching rate of gold is not better than that of NaOH combined with other additives.

The Effect of Ball Media with Different Diameters on Grinding Kinetics of Cassiterite-Polymetallic Sulphides

To investigate the effects of grinding media size on the grinding kinetics of cassiterite-polymetallic sulfide ores, the ball grinding media with diameters of 25mm, 30mm, 35mm and 40mm were studied in a laboratory ball mill. The results showed that the coarse and fine particles obeyed the first-order grinding kinetics laws in the process of grinding and the ball grinding media with 35mm diameter had a significant advantage on grinding up the coarse particles and controlling the generation of fine particles, which could provide theoretical guidance for practical production so that the grinding effects would be improved effectively and the problem of cassiterite over-grinding would also be settled very well.

Effect on Sedimentation Characteristics of Bentonite Suspension at Different Conditions

To better understand the sedimentation processes of bentonite, the sedimentation characteristic of bentonite suspension was studied by using the sedimentation analysis module of Dynamic Contact Angle Meter and Tensiometer. The results indicated that sedimentation characteristics of bentonite suspension were affected by the concentration and pH values of the suspension together with the dosage of dispersants. The natural sedimentation rates of bentonite suspension declined firstly with prolonging the sedimentation time and soon stabilized after about 50s. The sedimentation weight of particles hardly changed when the concentration ranged from 0.5% to 5.0%, while it increased significantly when ranged from 5.0% to 10.0%. The sedimentation weight and rate were relatively bigger at 4.4, 11.8 than that of 6.0, 7.9, and the maximum values appeared at pH11.8. Adding sodium pyrophosphate could improve the dispersibility of bentonite suspension.

Study on Grinding Kinetics of a Unique Double-Sphere Grinding Media for Cassiterite-Polymetallic Sulphide Ores

The grinding kinetics are strongly affected by the grinding media size and style, in order to improve the grinding efficiency and solve the over-grinding problem of cassiterite in the process of grinding in cassiterite-polymetallic sulfide ores plant. A unique double-sphere grinding media has been designed and the grinding kinetics of this media with different diameters for grinding products of different size fractions have been investigated in this paper.

Study on Grinding by a Double-Sphericity Abnormity Media

A double-sphericity abnormity media as grinding media was presented, and the grinding laws of cassiterite-polymetallic sulfide ore by the abnormity media and single ball media with different combinations were discussed in this paper. The results show that when adopting the abnormity media to replace its mother balls for grinding, the mother ball size is smaller, the grinding effect is better, and adding the abnormity media was helpful to decrease overgrinding. And for cassiterite grinding process, the desirable results could be achieved by using small size abnormity media to replace large single ball media.

Flotation Tests of Zinc Oxide Ore with Iron

Flotation tests for recovering zinc and iron from gossan ores was carried out in this paper. Flotation is the most commonly used method for beneficiation and pretreatment of oxidized zinc minerals. The effects of grinding fineness, amount of Na2CO3, amount of Na2SiO3, amount of Na2S and amount of octadecylamine were investigated, respectively. The results show that the grade of zinc and iron increase slightly, and the best result is that the grade of zinc and iron are 13.12% and 41.15%, the recovery of zinc and iron are 76.83% and 77.95%. The results simply indicated that flotation could not effectively recover zinc and iron from gossan ores studied in this paper.