Abstract

From a geostatistical viewpoint, non-linear interpolation is an attempt to estimate the conditional expectation, and further the conditional distribution of grade at a location, as opposed to simply predicting the grade itself. There are many non-linear methods now available. Disjunctive Kriging is one of them. This paper presents a comparison of ordinary kriging and disjunctive kriging in Choghart iron ore deposit in Yazd province, Iran. The case study consists of borehole samples measuring the Fe concentration. The sample data used in this study consist of exploration drilling data, suitably composited. The data set is irregularly spaced and has an almost normal distribution. Fe grade
was selected as the major regional variable on which the present research has focused. To carry out ordinary kriging and disjunctive kriging, spherical model was fitted over empirical variogram. To estimate the Iron grade, ordinary kriging and disjunctive kriging methods were used. All of the exploitable blocks with dimensions 20*20*12.5 (m³) were estimated. In the case of Choghart iron ore deposit the average of disjunctive kriging estimation error variance is 72.076 while the average of ordinary kriging estimation error variance is 100.278. So estimation with ordinary kriging is more risky.

Abstract

Generally during the preliminary exploration stages, the mineralization and exploration targets will be evaluated using mineral potential modeling. Mineral potential mapping includes recognizable mineralization determination criteria, data preparation, generating factor maps, and combining of factor maps into the appropriate inference networks. The Rudbar 1:100,000 map sheet is a part of western Alborz zone in NW Iran, and exploration layers including stream sediment geochemical anomalies, tectonics, alteration and lithology were processed with the purpose of determination of copper and gold targets in the Rudbar sheet. Finally, the data were integrated using the Analytical Hierarchy Process (AHP). Target areas were delineated as having high mineral potential for recognition the location of undiscovered copper and gold deposits in the investigated area, especially in central and southern parts of the area.

Abstract

n this paper a simulated annealing based algorithm has been presented to locate additional exploratory
drillholes based on the data obtained from the previous exploration phases. For this purpose, use has been made of a new criterion, namely the information value resulted from the exploratory drillholes. This criterion is based on the statistical value of information approach and is a logarithmic function of the kriging variance of the estimated block. The required codes for the use of this algorithm have been developed in the Matlab software. Also, a case study has been done in Sungon copper mine for its cross validation.

Abstract

Crushing plants that process different types of raw materials can be difficult to operate efficiently because of the differences in the characteristics of the input materials. The aluminosilicate plant grinding circuit studied has been operated without a screening of the primary crusher product and a proper definition of the plant’s apparent crushing capacity. In this study, samples of chamotte and bauxite were crushed at gape sizes of 35 and 17 mm, respectively and their maximum feed rates and particle size distribution determined. The results obtained showed that chamotte and bauxite were fed at the maximum feed rates of 8.3 and 6.3 tons/h, respectively. In addition, it was found that secondary crushing without scalping was inefficient as the percentages of undersizes obtained increased only marginally due to the choking of the secondary crusher. The introduction a scalping screen for the jaw crusher discharge was, however, found to increase the plant’s crushing capacities for chamotte and bauxite to 29 and 16.8 tons/h, respectively.

Abstract

Minerals processing engineers and grinding experts agree that classification efficiency and circulating load both have a major effect on the efficiency of closed circuit ball mills. However, the effect of each is difficult to quantify in practice as these two parameters are usually interrelated. Experimental work was undertaken by Metso Process Technology and Innovation (PTI) to better understand this relationship. The data obtained was compared to a simplified relationship for closed circuit grinding performance model, developed by Magdalinovic in 1991, to quantify the effect of classification efficiency and circulating load on the capacity of the circuit. The data also allowed an initial assessment of the model’s accuracy to be evaluated.

Abstract

The objective of this study was to investigate electrochemical properties of grinding environment of the
Sarcheshmeh porphyry copper sulphide ore. Influence of pH, solid content, water type, aeration condition and type of steel ball on pulp Eh, dissolved oxygen concentration (DO), open circuit potential (OCP) and EDTA extractable iron percentage and subsequently their influence on copper flotation were investigated. The results indicated that the low alloy steel balls had the lower Eh and DO values in relation to the high carbon chromium steel balls. The low alloy steel produces oxidized iron inside mill and reduces copper flotation. Gas changes from nitrogen to air and to oxygen resulted in higher Eh, DO and OCP values and consequently were caused formation of additional amount of oxidized iron species and lowered copper recovery. In addition, an increase in grinding pH and solid content and change of water type from tap water to distilled water decreased Eh and DO values and amount of EDTA extractable iron. It enhanced copper flotation.

Abstract

The present investigation deals with the recovery of iron values from the screw classifier overflow slimes of an operating iron ore washing plant using pilot scale flotation column (0.5 m diameter). Initially, selection of collector and optimization of process parameters like the dosages of collector and depressant and solids to liquid ratio during ‘reverse flotation tests’ was carried out on bench scale laboratory flotation cell. During the on-site pilot plant trials, operating parameters of flotation column such as air flow rate, froth depth, feed flow rate and wash water rate were optimized. Feed assaying Fe – 58.00%, SiO₂ – 6.21%, Al₂O₃ – 5.70% could be upgraded to Fe – 58.54%, SiO₂ – 5.29%, Al₂O₃ – 4.77% with weight recovery of 86.90% and Fe recovery of 88.97%. Iron oxide and alumina have identical crystal structure and at times exist in solid solution (one form of interlocked state). It appears that this contributed to limitations in separation of alumina from iron bearing minerals from these slimes.