1 DEPRESSION OF LEAD USING SODIUM METABISULPHITE IN SELECTIVE FLOTATION OF LEAD AND COPPER by Emre ÖZTÜRK Ekim, İZMİR
2 DEPRESSION OF LEAD USING SODIUM METABISULPHITE IN SELECTIVE FLOTATION OF LEAD AND COPPER ABSTRACT In this study, the complex lead-zinc-copper ore located in the territory of Canakkale Province, Yenice County, Kalkım District has been worked on. Flotation has been sellected as the appropriate enrichment method due to the physical and mineralogical characteristics of the ore. The optimum flotation conditions was determined. And then flotation tests were done to determine the depressant for selective flotation circuit of lead and copper. The existing environmental concerns about mining, direct the studies to reduce the environmental impacts. Potassium dichromate is an undesired chemical with carcinogen impacts and environmental drawbacks. Sodium metabisulphide is less dangerous than potassium dichromate for environment and human health. In flotation studies, sodium metabisulphide was used and percent cumulative recovery with percent Pb content and percent cumulative recovery with percent content was obtained. The positive and negative aspects of sodium metabisulphide, compared to potassium dichromate were discussed. Keywords: Sodium metabisulphide, Environment, Human Health, Flotation KURŞUN-BAKIR SELEKTİF FLOTASYONUNDA KURŞUNUN SODYUM METABİSÜLFİT İLE BASTIRILMASI ÖZ Bu çalışma Çanakkale İli, Yenice İlçesi, Kalkım Beldesi sınırlarında yer almakta olan kompleks kurşun-çinko-bakır cevheri üzerinde yapılmıştır. Cevherin fiziksel ve mineralojik özelliklerine uygun olan zenginleştirme yönteminin flotasyon olduğu görülmektedir. Çalışmada öncelikle cevher için optimum flotasyon şartları belirlenmiştir. Daha sonra kurşun bakır selektif flotasyon devresinde kullanılan bastırıcının belirlenmesi için testler yapılmıştır. Madencilik çalışmalarında var olan çevresel baskı, araştırmaların çevresel etkilerinin mümkün olduğunca azaltılması konularında ağırlık kazanmasına yol açmaktadır. Potasyum dikromat, kanserojen etkisi ve çevresel olumsuzlukları nedeni ile kullanımı istenmeyen bir kimyasaldır. Sodyum metabisülfit alternatifi çevreye ve insan sağlığına olan etkilerinin daha tehlikesiz
3 olması nedeni ile ön plana çıkmaktadır. Bu çalışmada, çalışmamıza konu olan cevherin zenginleştirilmesinde sodyum metabisülfit kullanılarak yüzde 89,74 kümülatif verimle yüzde 66,32 Pb içeren nihai kurşun konsantresi ve yüzde 35,67 kümülatif verimle yüzde 24,94 içermekte olan nihai bakır konsantresi elde edilmiştir. Bu verilerin ışığı altında sodyum metabisülfitin, potasyum dikromata göre olumlu ve olumsuz yönleri irdelenmiştir. Anahtar Kelimeler : Sodyum metabisülfit, Çevre, İnsan Sağlığı, Flotasyon 1. Intoduction Since Turkey has 6,7% of Pb-Zn- reserves of the world, these ores have great economical importance. In lead zinc copper mineralization, mainly sulphur combinations of galena (PbS), sphalerite (ZnS) and chalcopyrite (FeS 2 ) have been encountered. ( The impurities and side minerals have to be seperated as much as possible before.metallurgical transactions are applied, General purpose of enrichment of the complex ores is to get well separated concentrates. Otherwise, the economic value of the ore will reduced. In order to reduce the amount of in Pb concentrate and produce concentrate with higher economic value, bulk flotation concentrate has been subject to selective flotation. 2. Materials and Methods 2.1 Materials The ore used in the experiments, was produced in complex lead-zinc-copper mine pit located near Çanakkale Province, Yenice District, Kalkım town. Samples taken from stock area are completely crushed below the size of 2mm. The ore contains 3.29% Pb,.62% Zn,.35%, 3.38% Fe,.57% Mn according to the chemical analysis. Considering the results of chemical analysis and sieve-metal analysis, the ore is enriched below µm.
4 2.2 Methods The optimal conditions for bulk flotation of Pb-Zn- ore (Table 2.1) were determined. Table 2.1 Optimal conditions of bulk flotation Conditions Pb Bulk Dosage of Reagents Flotation Grain Size (mm) -,125 Ratio of Solid (%) ph 8,5 Na 2 SiO 3 (g/t) ZnSO 4 (g/t) 5 Na 2 S (g/t) 15 KEX (g/t) ,5 AF (g/t) Condition Time (min.) Flotation Time(min) Sodium metabisulphide and potassium dichromate are used individually as depressants for the selective flotation of Pb- regarding environmental impacts and economic efficiency. 3 Selective Flotation Of Pb- In lead-copper flotation circuit, potassium dichromate(k 2 Cr 2 O 7 ) is used as a deppressant at the Kalkım flotation plant. Potassium dichromate has carcinogenic effects and heavy metal content, thus it is recommended to add the minimum amount. In mining activities to minimize the environmental impact should be main goal. For this goal, using sodium metabisulfite stands out as a depressant. In this study using sodium metabisulfite and potassium dichromate were compared. Besides, different dosages of sodium metabisulphide were investigated. At first, sodium metabisulfite and potassium dichromate were compared at 5 g/t. Experimental conditions are stated in Table 3.1 and the experimental results using Na 2 S 2 O 5 are given in Table 3.2. Moreover, the results from experiments using K 2 Cr 2 O 7 is given in Table 3.3.
5 Recovery, Pb% Table 3.1 The experimental conditions using the applied Na 2 S 2 O 5 Conditions Pb Bulk Dosage of Reagents Flotation Grain Size (mm) -,125 % Solid in Pulp ph 5,5 Dextrin (g/t) 25 K 2 Cr 2 O 7 / Na 2 S 2 O 5 (g/t) 5 Aero 5 (g/t) 5 AF (g/t) Condition Time (min.) Flotation Time(sec) 1 Table 3.2 The results of the experiment with Na 2 S 2 O 5 weight grade % recovery % %. Pb Zn Pb Zn 29,65 39,68 4,11 9,64,29 46,37 46,63 Pb,35 42,64 1, 3,2 79,71 53,63 53,37 Table 3.3 The results of the experiment using K 2 Cr 2 O 7 weight grade % recovery % %. Pb Zn Pb Zn 5,84 31,61,48 9,34 9,34 68,18 69,12 Pb 94,16 56,,,82,66 31,82,88 According to the results for lead and copper ore, grade-recovery graphs (Figure 3.1) are also included. 5 Na2S2O5 Type of depressant K2Cr2O7 Recovery Pb% 5 Na2S2O5 Type of depressant K2Cr2O7 Şekil 3.1 Effect of the type of depressant in flotation
6 Results show that selectivity aren t fully achieved. Using zinc sulfate for activation of copper, increasing the amount of collector and depressant has been decided. Experimental conditions using K 2 Cr 2 O 7 are given in Table 3.4 Table 3.4 The experimental conditions using the applied K 2 Cr 2 O 7 Conditions Pb Bulk Dosage of Reagents Flotation Grain Size (mm) -,125 % Solid in Pulp ph 5,5 Dextrin (g/t) 25 ZnSO 4 (g/t) K 2 Cr 2 O 7 (g/t), Aero 5 (g/t) AF (g/t) Condition Time (min.) Flotation Time(sec) + The concentrate was produced with recovery of,69% and 59,77% Pb content; recovery of 75,8% and %15,86 content (Table 3.5 and Figure 3.2). The appropriate amount of potassium dichromate was determined regarding the enviroment and human health. Table 3.5 The results of the experiment using K 2 Cr 2 O 7 Dosage of weight grade % recovery % Reagents % Pb Zn Pb Zn 29,51 33,16 5,8 12,67 17,46 67,11 69,91 * g/t 9,19 35,86 1,84 5,87 5,88 7,58, Pb 61,29,11,92 1,74 76,66 25,31 19,99 15,83 22,75 1, 15,86 6,93 39,51 75,8 * g/t 5,27 23,51 1,45 2,34 2,38 15, 3,69 Pb 78, 59,77,27,,69 44,69 21,24
7 Recovery, Pb% 5 5 Dosage of K 2 Cr 2 O 7 (g/t) Recovery, Pb% Dosage of K 2 Cr 2 O 7 (g/t) Şekil 3.2 Effect of the dosage of K 2 Cr 2 O 7 to selective flotation Experimental conditions and the achieved results using Na2S2O5 are given in Table 3.6, Table 3.7 and Figure 3.3. Table 3.6 The experimental conditions using the applied Na 2 S 2 O 5 Conditions Pb Bulk Dosage of Reagents Flotation Grain Size (mm) -,125 % Solid in Pulp ph 5,5 Dextrin (g/t) 25 ZnSO 4 (g/t) Na 2 S 2 O 5 (g/t),, 5 Aero 5 (g/t) AF (g/t) Condition Time (min.) Flotation Time(sec) + Table 3.7 The results of the experiment using Na 2 S 2 O 5 dosage of weight grade % recovery % reagents % Pb Zn Pb Zn 26,2 35,42 2,35 8,82 17,39 75,64 88,49 (2) g/t 5,16,86 1,48 2,52 3,97 9,42 5, Pb 68,82,57,18,25 78,64 14,94 6,51 8,21 13,14 3,58 23,35 2, 37,87 83,57 (2) g/t 1,57 38,7 5,59,41 1,17 11,33 7,13 Pb,22 54,95,44,24 96,73 5, 9, 7,35 6, 2,28 24,94,74 31,39,7 (2) 5 g/t 1,46 23,27 8,59 13,,55 23,43 8,65 Pb 91,19 66,32,26,28 98, 45,18 11,28
8 Recovery, Pb% Dosage of Na 2 S 2 O 5 (g/t) Recovery, Pb% Dosage of Na 2 S 2 O 5 (g/t) Şekil 3.3 Effect of the dosage of Na 2 S 2 O 5 to selective flotation The flotation experiment using sodium metabisulphide (5 g/t) has achieved Pb recovery of 98,7% with 66,32% Pb content and recovery of,7% with 24,94% content that has commercial value. 4. Conclusions In lead - copper selective flotation circuit, sodium metabisulfite and potassium dichromate were tested as depressants. The lead concentrate with.69% recovery and 59.77% Pb content and copper concentrate with 75.8% recovery and 15.86% content is achieved by using potassium dichromate(g/t). The lead concentrate with 98,7% recovery and 66,32% Pb content and copper concentrate with,7% recovery and 24,94% content is achieved by using sodium metabisulphide (5 g/t). Both the feature may be sold in concentrate. The concentrate gathered by using sodium metabisulphide(5g/t) have higher grade and recoveries than concentrate gathered by using potassium dichromate(g/t). Potassium dichromate costs 1.45 times than sodium metabisulphide. Therefore, in terms of cost of consumption they are nearly equal. The use of sodium metabisulphide is economical since, a rise of 7% in grade and 8% in recovery for Pb, 9% in grade and 5% in recovery for was observed.
9 The heavy metal content of potassium dichromate cause environmental impacts and damage to human health. The aim of these studies was to reduce the negative impacts as much as possible by reducing or eliminate the usage of potassium dichromate. Regarding all these factors the use of sodium metabisulphite is strongly preferred for environment, higher grade and recovery and commercial value. Acknowledgements This study, is produced from the master thesis of same writer. I am heartily thankful to my supervisor, Assoc. Prof. Mehmet TANRIVERDİ, whose encouragement, guidance and support from the beginning to the final level enabled me to develop an understanding of the subject. Lastly, I offer my regards and blessings to all of those who supported me in any respect during the completion of this study. References Bayraktar, İ. ve Altun, Y.(1996) Kompleks bakır-kurşun-çinko cevherlerinin özellikleri, ekonomik değeri ve zenginleştirilmesi. Madencilik, Mart/1996 (35/1). Bulatovic, S. (7). Handbook of flotation reagents (1st Edition). Amsterdam: Elsevier Çilingir, Y. (1996). Metalik cevherler ve zenginleştirme yöntemleri (2. Baskı). İzmir: D.E.Ü Mühendislik Fakültesi Basım Ünitesi. Madencilik özel ihtisas komisyonu (1). Sekizinci beş yıllık kalkınma planı. Ağustos,