Baryte Ore Introduction

Beneficiation Nigerian Baryte Ore

Beneficiation Nigerian Baryte Ore

The mineral, Baryte (barium sulphate) is one of the major sources of barium and its compounds whose many uses are nearly hidden among the technical complexities of modern industrial processes and products. It is extremely important in the petroleum industry where, 80% of the world’s production of 44 million tons in 1973, was consumed by that industry in the form of a heavy fluid which is circulated in rotary drilling’1^. The remaining 20% went chiefly to the production of barium chemicals. Baryte is of common occurrence and is available from three major geologic types of ore deposits that is; vein, cavity filling and residual or bedded deposits.

In Nigeria, baryte is used mainly for drilling fluids by the petroleum industry. The increasing trend for its demand in the country is most likely to continue up to the end of this century so long as the economic activity in the petroleum sector is maintained.

With an envisaged increase in the use of baryte particularly for drilling purposes, it has become necessary to carry out some studies on the beneficia-tion and recovery of baryte. The introduction of a Structural Adjustment Programme (SAP) in Nigeria in 1986 forced a good number of industries to look inwards in the sourcing of their raw materials. The present study on the beneficiation of baryte ore was therefore carried out as part of a programme on the increasing use and exploitation of available raw materials.

Experimental

Lump ores were successively crushed using jaw, gyratory and roll crushers and the fined products were all smaller than 1180 /zm in size. Sampling was done by a Jones riffle and sample divider followed by grinding in a laboratory ball mill. Thereafter, the size distribution was obtained by placing a 200 g lot in a set of sieves and vibrating on a Rotap machine for 20 min. Chemical and sieve analysis on various portions of bulk samples indicated homogeneity in the elemental and size distribution.

A mineral jig (D24) was used for the gravity concentration of the ore following the method by Onyemaobi’2! and Uwadiale’3^ Magnetic susceptibility of Azare baryte was tested with the aid of Brownings high intensity magnetic separator at room temperature’4′.

The concentrates from all the tests were analyzed by the conventional chemical method and by the use of an atomic absorption spectrophotometer. The moisture content of the ore was determined by the wet loss method at 110°C

Results

Chemical composition of the head sample is as follows in wt pet: 98.03 BaS04, 0.28 A1203, 0.72 Fe203, 0.11 Na20, 0-05 K20, 0.10 CaO and 0.53 in loss on ignition and the results of sieve analysis are presented in Fig.l. Prom the results of assay distribution (Table 1), it can be seen that the barium distribution is highest in the size range between 710 and 500 /itn. The results of gravity separation are presented in Table 2. A concentrate with the barium sulphate content of 98.95% was obtained by jigging and it occupied 80.11 in wt pet (Table 3). The distribution of barium sulphate against particle size is illustrated in Fig.2.

Discussion

Determination of moisture content in ores is of vital importance since products are purchased on a dry basis and wet ores (especially wet coal) attract penalties proportional to their degree of wetness. The moisture content of the head ore of Azare baryte as analyzed, was 0.38%. It is believed, however, that the moisture content of an ore varies depending on the sample particle size distribution and at times, on which part of the bulk specimen, the sample was taken from. The moisture content also varies with temperature.

The aim of beneficiation is to produce a higher grade ore or concentrate in order to facilitate subsequent extraction process. The tailings go to ore dumps while the middlings may require further concentration treatment. The behaviour of minerals in the beneficiation process follows a particular pattern, that is, there is a plateau, covering a range of sizes within which the efficiency is a maximum, and it decreases at sizes larger or smaller than this range.

The recovery size relationship may change depending on a number of factors such as the specific gravity of the valuable minerals.

Conclusions

  • Azare baryte can be concentrated to give a product suitable for use particularly in oil drilling operations.
  • Jigging, but not magnetic separation, has been found the better method for the beneficiation of Azare baryte.
  • Although there is a high distribution (98.03%) of barium sulphate in the coarse size fraction (-1180^+125 /xm), an average barium sulphate content of 95-07% is obtained.
  • The slight increase in value from 95.07% to 98.95% after jigging operations is considered significant since the new value conforms to the minimum requirement of 94% to 98% barium sulphate by the chemical, paint and petroleum industries.

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