MODARES TECHNICAL AND ENGINEERING
Year:2002 | Volume:- | Issue:9|Papers Count:10

Reductive leaching has extensively studied for the recovery of valuable metals from manganese nodules. In the present research, this method was used for the extraction of cobalt from lateritic ores. Preconcentrated cobalt ore from Tidar deposit was leached with sulfuric acid in the presence of phenol as reducing agent and effects of various factors on the cobalt recovery were investigated. These factors included sulfuric acid concentration, phenol content, pulp density, temperature and time. In order to determine the effect percent of various factors, screening stage was used by using Taguchi method. The results indicated that temperature, sulfuric acid concentration, time, pulp density, phenol content and interaction between temperature and time, acid concentration and temperature, pulp density and temperature, acid concentration and time were effective factors on the c9balt recovery. Under optimum conditions the recovery of cobalt which was obtained was about 95%.

Mineral processing could be divided into Combination and Concentration. Comminution is one of the most significant steps in mineral processing which has found wide applications in other engineering fields. Grinding aids/chemicals are used in grinding circuits to change the ores breakage characteristics. Size analysis methods have important role and application in mineral processing. There are some size distribution functions to estimate size distribution such as Rosin - Ramler. In this study, the effect of grinding aids such as Sodium Tri Poly Phosphate (STPP) and (NaOH) on Sarcheshmeh copper ore and Galiran coal ore samples, were carried out by using Rosin - Ramler function. The effect of STPP and NaOH on breakage parameters of Sarcheshmeh copper and Galiran coal samples had been analyzed using Rosin - Ramler function.The results have shown that there was a considerable correlation between breakage parameters and Rosin- Ramler function. The changes of Rosin - Ramler function coefficients can be used as a good criteria and guideline to analyze the effect of grinding aids on breakage parameters such as grind ability, mill production and fineness mean size.

In this research, the recycling of some heavy metals such as lead, chromium and nickel from waste water has been investigated by using the biological activity of sulfate. Preliminary laboratory work indicates through biological reduction the heavy metal ions can be removed/recovered from diluted aqueous solutions. Successful application of this technology enables the removal, detoxification and recycling of metals, along with the destruction of organic compounds in a single- treatment step. Bioremediation of metals is through the process of sulfate-reducing bacteria (SRBs). Precipitation of insoluble metallic sulfides and production of bio-genic hydrogen sulfide are the main mechanisms of the system. The test results are also verified through well known geo-chemical model MINTEQ.

Angouran lead and Zinc Flotation Plant is located about 95 km away from Zanjan city. This plant is one of the largest lead and zinc concentrates producers in Iran the feed which contains two types of low and high-grade zinc ore. The high-grade feed contains more than 33% zinc and less than the low-grade one. The low-grade ore is screened into two size fractions, -2 mm and +2 mm. The -2 mm fraction goes to the Pb flotation circuit. The tailing from the -2 mm fraction circuit, which contains 20-23% of zinc, is sent to tailing dams. In this research zinc was recovered from this tailings by using sulfuric acid.The tails sample was first calcined at 800°C for an hour and then subjected to quantitative and qualitative analysis. The results show that the sample contains 28.89% of zinc and zincite and willimite are major zinc minerals bearing.The effects of factors such as stirring rate, temperature, initial acid concentration and solid/liquid ratio, on zinc recovery were studied. The results obtained show that in the best conditions, about 91% of zinc were recovered using a stirring rate of 800 rpm, a reaction temperature of 50°C, a 30 minutes reaction time, a 100 g/l initial sulfuric acid concentration and solid/liquid ratio of 1/6 g/ml.

Lakan is one of the concentrating plants in Iran which is located about 40 km far from Khomein. Plant was fed from Emarat nime ore which contains zinc in sulphidized and oxidized form, in particular, sphalerite and smithzonite. The former was floated while the latter was collected as a tailing. The aim of the present research is to recover oxidised zinc from tailing.Mineralogical study and chemical analysis of tailing showed that smithzonite is the main valuable mineral in the oxidized ores, and quartz exists as gangue. The total amount of zinc and lead in the tailing were about 3.2% and 0.8% respectively.In order to recover oxidized zinc from tailing, flotation method was applied using cationic collectors. At the optimum conditions, the grade and recovery of zinc using amine (Armac T) were 24.7 and 53.6%, respectively.

Optimization of the processes is one of the most important tasks today, for highly competitive industries. High cost of research and development activities has necessitated development of the experimental methods by which the factors affecting a process could be determined by performing a minimum number of experiments. These types of experimental designs have been used since 1980.Among different methods of experimental designs, the Taguchi method -because of its comprehensive nature and its ability to enable designs which are resistant to uncontrollable parameters has found wide spread applications.The Sarcheshmeh copper ore, which mainly consists of Chalcopyrite, was studied by Taguchi method. The effect of seven factors namely collectors, Z11 and R407, frothers, pine oil and A65, particle size, pH and residence time were investigated. The results showed that an increase of minimum of 5% in copper recovery could be obtained using the Taguchi type of experimental design.

To improve the procedure of ornamental stone quarries design, a research program was conducted under the title of "The Effect of Discontinuities on the design of ornamental stone quarries" at Shahrood university. In this study, IBSD or "In Situ Block Size Distribution" of rock, was considered as a parameter, which could assist the design engineer in decision making on the feasibility study procedure.Scan line sampling method was used for collecting discontinuity data while K-means method was used to cluster the discontinuities and classify the discontinuity sets as well.Based on the above, a user friendly software named "Geoquary" was developed. Using this software the design engineer can have a three dimensional view of the sight and process the discontinuity data collected from the field and evaluate the IBSD. As the block sizes in a rock mass play an important role in the design of an ornamental stone quarry, the design engineer can make decisions about the mine, with a higher degree of confidence.