Denizli-Tavas manganez cevherlerinin asidik liçi ve proses optimizasyonu

Abstract

Bu çalışmada Denizli-Tavas yöresi manganez cevherlerinin hidro ve elektrometalurjik yollarla işlenerek metalik manganez üretiminde ilk adım olan çözümlendirme proses parametrelerinin optimizasyonuna çalışılmıştır. Bu amaçla liç veriminde etkili olacağı tahmin edilen bazı parametrelerin optimizasyon deneyleri yapılmıştır. İlk aşamada tane boyutunun liç verimine etkisini gözlemek amacıyla değişik tane boyutlarında çalışılmıştır. Daha sonra sıcaklığın liç verimi üzerine etkisi incelenmiş ve optimum liç sıcaklığı saptanmaya çalışılmıştır. Daha sonraki aşamalarda asit konsantrasyonu ve katı/sıvı oranının liç verimine etkisi incelenmiştir. Son olarak liç işleminden önce cevhere kalsinasyon işlemi yapılmış ve kalsinasyonun liç verimine etkisi gözlenmiştir. Yapılan çalışmalar sonucunda tane boyutunun azalmasıyla liç verimi artmış ve sıcaklığın 20°C'den 50°C'ye çıkartılmasıyla liç verimi %73'ten %89'a yükselmiştir. Asit konsantrasyounun 1 M H^SCVten 1.5 M H2S04'e artırılmasıyla %97 verime ulaşılmıştır. 1/20 katı/sıvı oranında ise %100 liç verimi elde edilmiştir. Cevhere yapılan kalsinasyon işlemiyle cevherin manganez içeriği %31.60'tan %38.70'e yükselmiş ve oda sıcaklığında yapılan deneyde liç veriminde %16'lık artış sağlanarak %86'ya ulaşılmıştır. Deney sonuçlarından elde edilen datalar kinetik modellere uygulanmış, CGB modeliyle uyum içerisinde olduğu görülmüştür. Manganez çözünmesinin difüzyon kontrollü kontrollü bir mekanizmayla gerçekleştiği ve aktivasyon enerjisi 7 Kcal/mol olarak bulunmuştur.

Manganese takes place in the 7th group of the periodic table of the elements. Its atomic number is 25 and atomic weight is 54.93 gr/mole. Identified land-based resources are large but are irregularly distributed. The Republic of South Africa and U.S.S.R account for more than 80% of the world's identified resources. Extensive marine accumulations of manganese as oxide nodules on ocean floors and as oxide crusts at shallower depths may have future commercial significance. Table 1 gives the production of manganese ore of selected countries. ?Estimated The largest portion of ore consumption was related to steel production, directly through upgrading of ore to ferroalloys and metal. Most of remaining ore was used for such non metallurgical purposes as producing dry cell batteries, as an ingredient in plant fertilizers and animal feed, and as a colorant for brick. Manganese compounds occur in a great many minerals forms widely distributed throughout the crust of the earth. The most common sources of the element are VII the minerals; pyrolusite and psilomelane. Table 2 gives the chemical composition and weight percentage of manganese minerals. Table 2- The chemical composition and weight percentage of common manganese minerals. Manganese metal is used both as a deoxidizing agent and as an essential constituent to improve the properties of nonferrous metals and alloys and is used where a minimum of iron and carbon are desirable. As an alloying element in the production of nonferrous alloys, manganese improves strength, ductility and hot rollling properties. It is used as an alloying element and a cleanser in aluminum alloys, aluminum bronze, constantan, manganese bronze, Monel and related products, Everdur, nickel-chromium resistance alloys and nickel-silver. Some copper-manganese alloys employed chiefly in bimetallic temperature-regulating devices are made only with electrolitic manganese. In this study, manganese ore obtained from Denizli-Ulukent Manganese Company is used. This ore is exported. The chemical composition of the ore is given Table 3. To determine the optimal leaching conditions a group of expriments were done in sulphuric acid solutions. The effects of particle size, temperature, acid concentration, solid/liquid ratio and calcination on leaching of manganese ore are investigated. For this purpose, firstly leaching experiments were carried out at 0.5 mm-0.038 mm particle size. The results obtained from the leaching experiments are given in Table 4. VIII Table 4-The effect of particle size on the manganese dissolution efficency And then leaching experiments carried out at 20, 30, 40, 50°C temperatures and at 50°C optimum leaching temperature is obtained (Table 5). The effect of acid concentration at 50 °G is also investigated. At 1.5 M H2SO4 concentration 97% at manganese is extracted in solution and at 2.0 M H2SO4 concentration 99% of manganese is extracted. The effect of acid concentration is given in Table 6. Table 6-The effect of acid concentration on manganese dissolution efficency. At 50°C temprature, 1.5 M H2SO4 concentration, 850 rpm stirring speed and 1/20 solid/liquid ratio, 100% manganese extraction are given in Table 7. IX Table 7- The effect of solid/liquid ratio on manganese dissolution efficency. Finally, experiments were carried out determine the influence of calcination. For this purpose, manganese ore (-0.106;+0.075 mm particle size) was calcined at 800°C for 1 hour and the calcined ore was leached. The effect of calcination is given in Table 8. Tablo 8- The effect of calcination on manganese dissolution. From a large number of leeaching tests where narrow size fractions of a manganese ore were treated by sulphuric acid solutions under different conditions, it can be concluded that CGB model gives the aggrement the experimental and calculated results. From the effect of temperature experiments results the apparent activation enerjy was calculated of the reaction. The [l-2/3X-(l-X)]2/3 against time plots are shown in Figure 1. The Arrhenius plot is given in Figure 2. The apparent activation energy, Ea, is 7 Kcal-mole. < X 0.20 0.18 0.16 0.14 0.12 w 0.10 >< cr, 0.08 - 0.06 0.04 0.02 0.00 ? 20*C D 30*C A40*C A50*C -i - ? - i - i I - i - i i i I i i i i I i ?????? -1 i - i i i l_i i i i_ 0 25 50 75 100 125 150 175 200 Time (min) Figure 1- Plot of [1-2/3 X-(l-X)]2'3 against time for different temperatures. -11.50 3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 3.50 1000/T(1/K) Figure 2- Arrhenius plot of log k versus T".