Ali Ihsan Arol

Effect of microwave heating on magnetic separation of pyrite

Abstract The effect of microwave heating on magnetic processing of pyrite was investigated. Different size fractions of pyrite were treated (heated) in a microwave oven at 2.45 GHz frequency and different power levels. The microwave treated pyrite samples of −420 μm fraction were subjected to magnetic separation at magnetic field intensities of 0.1, 0.3 and 0.5 T. It was found that pyrite was converted to such ferromagnetic minerals as pyrothite and γ-hematite, and magnetic separation recovery was improved after microwave treatment.

Gold cyanide adsorption characteristics of activated carbon of non-coconut shell origin

Coconut shells are the most widely used raw material for the production of activated carbon suitable for gold production by cyanide leaching. However, increasing gold production is likely to necessitate the exploitation of other sources. Abundance and ready availability of hazelnut shells, apricot and peach stones make them a viable candidate for an alternative source. In this study, activated carbons made of these materials have been tested to determine their suitability for gold metallurgy. Parameters of carbonization and activation have been optimized. Gold loading capacity and adsorption kinetics have been studied.

USE OF BORON WASTE AS AN ADDITIVE IN RED BRICKS

In boron mining and processing operations, large amounts of clay containing tailings have to be discarded. Being rich in boron, the tailings do not only cause economical loss but also pose serious environmental problems. Large areas have to be allocated for waste disposal. In order to alleviate this problem, the possibility of using clayey tailings from a borax concentrator in red brick manufacturing was investigated. Up to 30% by weight tailings addition was found to improve the brick quality.

Method to improve preheated and fired strengths of haematite pellets using boron compounds with organic binders

Abstract Organic binders as alternatives to bentonite in iron ore pelletisation have found limited application since they fail to give enough mechanical strength to preheated and fired pellets. This paper describes the use of alternative binders to bentonite for haematite ore pelletisation. Organic binders (carboxyl methyl cellulose, corn starch, dextrin) and agglomeration aid chemicals (polymer and flocculants) and boron compounds (colemanite and borax pentahydrate) were tested as binder alone or in combination. The influence of the boron compound added organic binders on the preheated and fired pellet strengths was determined. The results showed that the compressive strengths of preheated pellets at 1000°C made with organic binders can be improved with the addition of colemanite. The compressive strengths of fired pellets at 1300°C produced with organic binders plus colemanite were found to be significantly greater than those of pellets bonded with the reference bentonite binder.

Using marble wastes as a soil amendment for acidic soil neutralization.

One of the most important factors limiting plant growth is soil pH. The objective of this study is to determine the effectiveness of marble waste applications on neutralization of soil acidity. Marble quarry waste (MQW) and marble cutting waste (MCW) were applied to an acid soil at different rates and their effectiveness on neutralization was evaluated by a laboratory incubation test. The results showed that soil pH increased from 4.71 to 6.36 and 6.84 by applications of MCW and MQW, respectively. It was suggested that MQW and MCW could be used as soil amendments for the neutralization of acid soils and thus the negative impact of marble wastes on the environment could be reduced.

Use of Boron Compounds as Binders in Iron Ore Pelletization

Abstract: Low grade iron ores with impurity gangue minerals containing silica and alumina must be upgraded to an acceptable level of iron content. Concentrates, due to their fine sizes, are not suitable to be directly charged to the iron-making processes such as the blast furnace or the DR-plant. Hence, an agglomeration technique should be applied to fine concentrate. The most commonly employed one is pelletizing in iron ore industry. In pelletizing, iron ore, water and a binder are balled in a mechanical disc or drum to produce agglomerates. Bentonite is the most widely used binder. However, it is considered as an impurity due to its high SiO 2 and Al 2 O 3 content. Many researchers have investigated different binders, mostly of organic origin, in pursuit of finding a viable alternative binder to bentonite. Organic binders were found to yield good quality green and dry pellets. However, they fail to impart enough strength to the pre-heated and fired pellets as a result of insufficient slag bonding. Boron compounds free of silica and alumina are thought to be a potential solution to overcome the lack of slag forming constituents encountered with organic binders as they are known for their low melting temperatures as well as for their ability to also lower the melting temperatures of silicates. A few researchers have investigated the use of boron compounds in iron ore agglomeration and found promising results which have been covered in this paper.

Effect of Sodium Silicate on Flocculation of Hematite with Starch in the Presence of Calcium

Sodium silicate is used as a dispersant in the selective flocculation of iron ores with starch as the polymeric floccullant. The mechanism of its dispersive effect on quartz has been reported to be related to its ability to remove coagulants, such as calcium and magnesium ions, from the process water. The interaction between iron oxides and calcium and sodium silicate, which has not appeared in literature, is also an important factor that would contribute to the success of the selective flocculation process. To elucidate the nature of this interaction at pH 11, where selective flocculation of iron oxides is commonly carried out, the effect of calcium and sodium silicate on the flocculation–selective flocculation behavior of hematite was investigated. Abstraction of calcium and adsorption of starch by hematite at different concentrations of sodium silicate and calcium were determined. It was found that calcium silicate precipitates as well as sodium silicate prevented starch adsorption and, therefore, sodium silicate could only be used effectively below 10 mg/L calcium and 1000 mg/L SiO2 concentrations while dispersing a hematite–quartz mixture.

The Effect of Calcined Colemanite Addition on the Mechanical Strength of Magnetite Pellets Produced with Organic Binders

Iron ore pellets must have sufficient mechanical strengths against degradation in all stages of pellet production. Low strength is also a problem for product pellets since they abrade during transportation to the reduction furnaces. The use of a binder is necessary to provide sufficient strength to the pellets and for better operation and handling of pellets. Bentonite is the standard binder in the industry; however, it is considered an impurity due to its acid oxide contents. Organic binders have been tested for many years as alternative binder to bentonite. They have been found to give sufficient wet pellet properties. However, they failed to provide sufficient strength to the preheated and fired pellets due to lack of slag bonding. It has been assumed that one possible effective method to improve the preheated and fired pellet strengths is addition of a slag-bonding constituent. In this study, calcined colemanite was added to the pellet feed to overcome the lower strength problem encountered with organic binder use. The strength of pellets produced with organic binders and calcined colemanite alone and in combination was comparatively studied against the strength of pellets made with standard bentonite binder in magnetite concentrate pelletizing. The results showed that addition of calcined colemanite into the pellet mixture improved the preheated and fired pellet strengths of pellets produced with organic binders.

Changes in the chemical composition of an acidic soil treated with marble quarry and marble cutting wastes

Soil acidity greatly affects the availability of plant nutrients. The level of soil acidity can be adjusted by treating the soil with certain additives. The objective of this study was to determine the effect of marble quarry waste (MQW) and marble cutting waste (MCW) on the chemical composition and the acidity of a soil. Marble wastes at different rates were applied to an acid soil. Their effectiveness in neutralizing the soil pH was compared with that of agricultural lime. The changes in the chemical composition of the soil were also evaluated with column test at the end of a 75-day incubation period. The results indicated that the MQW and MCW applications significantly increased the soil pH (from 4.71 up to 6.54), the CaCO3 content (from 0.33% up to 0.75%), and the exchangeable Ca (from 14.79 cmol kg(-1) up to 21.18 cmol kg(-1)) and Na (from 0.57 cmol kg(-1) up to 1.07 cmol kg(-1)) contents, but decreased the exchangeable K (from 0.46 cmol kg(-1) down to 0.28 cmol kg(-1)), the plant-available P (from 25.56 mg L(-1) down to 16.62 mg L(-1)), and the extractable Fe (from 259.43 mg L(-1) down to 55.4 mg L(-1)), Cu (from 1.97 mg L(-1) down to 1.42 mg L(-1)), Mn (from 17.89 mg L(-1) down to 4.61 mg L(-1)) and Zn (from 7.88 mg L(-1) down to 1.56 mg L(-1)) contents. In addition, the Cd (from 0.060 mg L(-1) down to 0.046 mg L(-1)), Ni (from 0.337 mg L(-1) down to 0.092 mg L(-1)) and Pb (from 28.00 mg L(-1) down to 20.08 mg L(-1)) concentrations decreased upon the treatment of the soil with marble wastes.

Use of waste pyrite as an alternative to gypsum for alkaline soil amelioration

The reclamation of alkaline soils is of great interest especially in arid and semi-arid climatic regions of the world. The aim of this study was to investigate the application of pyrite from the waste materials of a copper concentration plant as an alternative to gypsum application for alkaline soil amelioration. The second aim was to assess heavy metal contamination. Waste pyrite (FeS2) obtained from a copper concentration plant and pure gypsum (CaSO4·2H2O) were added to soil within the columns and pots. Column-leaching tests were performed to determine the effectiveness of waste pyrite application on alkaline soil characteristics as compared with gypsum application. Greenhouse pot experiments were also conducted for evaluating the effects of these soil additives on plant growth. The results indicated that the pH and exchangeable sodium percentage of the experimental soil significantly decreased (p < 0.01) upon waste pyrite and gypsum applications. While waste pyrite was very effective in increasing the levels of essential plant micro-nutrients and dry matter weight of wheat, it did not cause pollution or toxicological problems in the soil. The results of this study clearly indicated that waste pyrite is a good ameliorating agent and an alternative to gypsum in reclamation of alkaline soils.