Konya Helvacıbaba manyezit cevherinin flotasyonla zenginleştirilmesi

Abstract

Bu çalışmada Konya Helvacıbaba Manyezit-Cevherinin petrografik etüdleri, kırma, öğütme, elektrokinetik potansiyel, mikroflotasyon, flotasyonla zenginleştirme deney ve sonuçlan sunulmuştur. Mineralojik incelemeler cevherin manyezit az miktarda kalsit, dolamit, kuvars, indingisit, serpantine, sepiolit, manyetit ve hematit minerallerinden oluştuğunu göstermiştir. Manyezit serbestleşmesi ve zenginleştirilmesinde magnezitin alterasyonu sonucu manyezit kümeleri çevresinde oluşa silikatlar etkili olmuş ve bu nedenle ve bu nedenle cevheri ince boyutlara (0.210 mm altı) öğütmek gerekmiştir. Manyezit serbestleşmesi ve zenginleştirilmesinde manyezitin alterasyonu sonucu manyezit kümelerinin çevrelerinde oluşan silisli mineraller daha etkili olmuş ve bu nedenle cevheri ince boyutlara (0.210 mm altı) öğütmek gerekmiştir. Silis içeren demirli mineraller azmiktarda olduğu için (<%1) mayetik ayırma yoluyla silisi istenen oranda uzaklaştırmak mümkün olmamıştır. Bu çalışmada cevherin flotasyon yoluyla zenginleştirilmesi imkanları araştırılmıştır. Flotasyon deneylerinde %45.74 MgO, % 0.13 A1203, % 0.28 Fe203, % 5.22 Si02, %0.80CaO içeren tuvenan cevher kullanılarak, uzun zincirli aminlerle silikatlar yüzdürülmüş ve yüzmeyen kısımda manyezitin zenginleştirilme çalıştırmaları yapılmıştır. Anyonik kollektörlerle yapılan flotasyon deneylerinde iyi sonuç alınamaması nedeniyle çalışmalar bu yönde geliştirilmiştir. Aminlerle yapılan flotasyon deneylerinde tane boyutu, kollektörtipi, kollektör miktarı, pH değeri ve pülpte katı oranının flotasyona etkisi incelenmiştir. Aminlerle yapılan flotasyon deneylerinde aşağıdaki şartlarda en iyi sonuçlar alınmıştır: PH : 8.0 Pülpte Kati Oram :%1 2 Kollektör :Armac T (Tallow amine acetate) Gazyağı Miktarı : 1 4 kg/ton Tane Boyutu :-0.2 1 0 mm Deneyler Sonucunda :6 kg/ton aminle 15 dakika kıva süresi sonucunda %55.30 verimle % 2.20 Si02 içeren konsantre elde edilmiştir.

Magnesia is one of the most important subtances in refractory manufacturing. Its value is mainly depending on the impunities such as silica, iron and calcium minerals. Magnesite ores are considered as extra quality, if silica cotents are less than one percent. Ores containing more than 3 percent silica can be used to produce the refractory materials after blending with the low silicious ores. In Turkey, there are large magnesite deposits in a poligon surrounded by Eskişehir, Kütahya, Bursa and Konya Magnesite ores occur in this area on serpantine and ultrabasic rocks after alteration of this rocks depending on the atmospheric coditions and/or underground water and gases. Magnesite in cryptocrystalline structure take froms in these ultrabasic rocks as weins, thick layers and stock-werks. The adjoining minerals in the magnesite deposits are mstly serpentine and olivine with some quartz, calcedony and sepiolite which are the main silica source of the ore bodies. Magnesite deposits, nowadays, requires mineral processing for both to be aple to optain now materials in order to meet the requirments of the refracter technology. Magnesite ores generally contains compositions like dolomite, calcite, burisite serpantine, talk and soluble salts in addition to magnesite. Spatis magnesites are beneficated more difficulty than cryptocrystalline type. The method used today will be hand sorting if there is a liberation between magnesite and the gangue minerals. The benefication method both hand sorting and using automatic equipment are applied to the magnesite ores which are over 40mm size makig use of the difference between the color and the structure. Despite the hand sorting method gives the chance to optain coarse size and low cost concentration in magnesite ores other benefication processes are needed to be used due to the contains of fine impurities. In the heavy media seperation of benefication processes, it is ade use of specific gravity differences between the magnesite and the gang marerial. In the electrostatic seperation, however, the should be an electric conductivity difference between magnesite and the gang materials. In magnatic seperation, specially, is applied to cryptocrystalline magnesites which contains serpantine in the gangue. In order to seperate the magnesite with no ferrium empunties from serpentine in suitable size serpantine should not loose its magnetic properties due to alteration. vu New applications concerning with magnetic seperation is now posible after the development of magnetic seperators called "PermroU". In this seperators the operation costs are considerably low and the magnetic fields density are high. Comparing to drum and disc seperations. Especially the effects of these seperators on the magnesite ores above +10 mm size magnesite ores can economcally be preconcentrated. In graded calcination methods of beneficiation. It is made use of the chananactenstics of calcine and dolomite which are calcinated at lower temperatures than magnesite. Before clasical flotation tests, phsysical properties, chemical compositions and mineralogical characteristics were investiqated. For the pure minerals. The main impruties are determined as silica minerals in magnesite by chemical analysis, X-Roy Difraction and electron microscopy studies. All magnesite samples have negative surface electriicity in a wide pH range over 7 eith the higherst negativity. This thesis the encompasses results of a laboratory investigation carried out on representitive samples of Konya Helvacıbaba Magnesite Ore Deposit. The Laboratory work essentially consists of size reduction operations and beneficiation by flotation. The ore contains several accessory minerals. Of these, quartz, serpantine, indinqisite and sepiolite make up he siliceous minerals and calcite and dolomite represent to the calcium content of the ore (Table 1). Table 1. Mineralogical compo. of the Ore Magnesite and sepiolite minerals are finely disseminated and are intimately associated with each other. Hence, conventional methods of hand-sorting and heavy- medium seperation has not been applicable for the separation of sepiolite and the other silicates from magnesite. The sepiolite, resulting from the alteration of magnesite was found to be the deciding factor in the liberation of the ore. In order to achieve sufficient liberation, it was necessary to reduce the ore sample to minus 0.210 mm, prior to concentration. viu The amount of magnetic minerals in the ore was very small (approx 1%), and hence, magnetic separation was regarded unsuitable for the beneficiation of the ore. Flotaion was considered to be the most suitable method of beneficiation for Ibis ore and was investigated for this ore in detail. However, flotation requires expensive grinding, and the concentrate obtained by flotation needs to be calcined and briquetted in order to from a suitable feed for the production of dead-burnt magnesites. Approximately 200 kg representative sample was taken systematically from the stockpile and then brought to the Mineral Processing Laboratory of Istnbul Technical University. Experimental work were carried out on the sample dryed at room temperature. The chemical properties of the sample were determined by chemical analysis (Table 2). Table 2. Chemical Analysis of Raw Ore In the experiments carried out for the flotation of the silicates (reverse flotation), the effects of particle size, type of collector, amount of collector, pH value, percentage of solids in the pulp and removal of slime prior to flotation were investigated. Zeta Meter 3. O equipped with a microprocessor unit was used to measure the zeta potential of magnesite and gangue minerals. The unit automaticaly calculates the electrophoretic mobility of the particles and converts it to the zeta potential. One gram of mineral was conditioned in 100 cc of distilled water for 1 minutes. The suspension was kept still for 5 minutes lo let larger particles settle. Each data points is an average of approximately 10 measurements. All measurements were made at ambient temprature correction factors provided in the instruction manual. In order to examine the ad sarption mechanism of reaqents in magnesite flotation, electrokinetic potential and zero pointof charge of pure magnesite serpantine and sepiolite were determined, the effect of various ions such as, Mg2+, Ca2+, Na+, CO2;' and flotation reagents such as, amine and sulfate on surface properties of magnesite, serpantine and sepiolite wre examined. Magnesite, serpantine and sepiolite has Zpc (Zero point of charge) at pH 9.5, 6 and 4. Above this pH value Surface is negative and under this pH value surface is positive. IX The silica content of magneite ore of Konya District is derived from serpentine. It is possible to seperate opal from magnesite by hand-picking, but serpentine ise usually finely disseminated and cannot be seperated by hand-cobbing. As magnesite mineral is in the cryptocrystalline form, concentration of magnesite by flotation! is not possible. Microflotation experiments were applied to magnesite, sepiolite and serpantine in order to compare their flotation abilities. A modified microflotation cell was used for this purpose tests were conducted to determine flotation recovery as a function of pH, the type and the amout of collector and modifying agents. The results can be summarized as follows. - Flotation recovery of magnesite reach to nearly 80 percent at pH: 8-10, when 10-4 Mol/1 sodium aleat is used. -When the amount of sodium aleate increases twice, the recoveries of magnesites are also increased. -Serpatine floats with 80 percent of recovery at pH:8 when Armac T is used. The results of clasical flotation obtained are summarized below: The effect of the type of collector: The type of collectors, includig Armac T (Tallow amine acetate), Hydroxamate, and Oleyil Sarkosin were used and Armac T was found to be the most suitable. The effect of particle size: Ore samples ground to minus 0.210,.0150, 0.106, 0.074 and 0.038 mm, were used and the best results were achieved with the minus 0.210 mm size. The effect of amount of fuel oil: Fuel oil was used in amounts of 2, 4, 6, 8, 10, 12, 14, 16 and 20 kg/ton, of which 14 kg/ton gave the best results. The effect of the percentage of solids in the pulp: Varius percentages of solids were used in the pulp, ranging betwee 12 and 70%, and the best value was found to be 12%. The effect of pH value: Flotation tests were carried out at various pH values raging betwee 7.0 and 10.0 At pH values below 6, magnesite dissolved and made the flotation impractiable. The results obtained in the range of 7.0 to 10.0 pH values, were plotted on a qraph, from which the best pH value was found to be 8.0. The effect of the amount of colleton Armac T (Tallow amine acetate), having been found the best collector, was used inn amount of 2, 4, 6, 8, 10, 15, 20, 30 and 60 kg/ton, of which 6 kg/ton gave the best results.