SHORTMuhammad COMMUNICATION Akbar et al., J.Chem.Soc.Pak., Vol. 41, No. 03, 2019 555
Proximate and Trace Metal Analysis of Pakistani Coal
1Muhammad Akbar, 1Muhammad Abdul Qadir, 2Ayoub Rashid, 3Abrar Hussain, 4Khalid Bhatti and 2Ahmad Adnan* 1Institute of Chemistry, University of the Punjab, Lahore, Pakistan. 2Department of Chemistry, Government College University, Lahore, Pakistan, 3University of Education, Lahore, Pakistan. 4Government P/G College Fatepur, Layyah, Pakistan. [email protected]*
(Received on 9th May 2018, accepted in revised form 7th March 2019)
Summary: Pakistan is facing severe energy crisis with depleting water and gas reservoirs. Pakistan has large reserves of coal found exclusively in Sindh, Baluchistan and Punjab, but this coal is regarded as low rank (Lignite grade). Present work aimed at the determination of the quality of coal by Proximate and trace metal analysis. Three coalfields including Dukki (Baluchistan), Chamalang (Baluchistan) and Salt range (Punjab) were selected for study. Proximate analysis and calorific values of coal samples were carried out using reported protocols and trace metal analysis including Co, Cr, Ni, Pb, Zn, Cd and Cu was done by ICP employing standard procedures. Results suggested that the coal belonging to these areas is of sub-bituminous type. Chamalang coal of Baluchistan was found to be of better quality than Dukki and Salt Range coal.
Keywords: Coal, Proximate analysis, Calorific value, Ultimate analysis, Trace metals.
Introduction
For the last couple of decades, power when fired in power generation, incineration plants, shortage has become an enduring problem around the smelting, or combustion engines produces a variety plant, particularly in developing countries like of products responsible for environmental and health Pakistan. In addition, the rapid growth in population issues [4-6]. A number of methods have been and technological revolution has further exacerbated established to measure the emission of these the energy crises. According to various official and pollutants with a high degree of accuracy. Coal private surveys, [1] the demand of electricity around contributes about 40% in power generation and in the Country is increasing by 6-8% annually and return, these coal fired power plants emit CO2, SO2, overall power shortfall has been estimated between N2O, NOx, mercury, arsenic, vanadium, 5,000-8,000 MW. To cope with energy challenges, molybdenum, cadmium, along with some other Pakistan likewise many other developing countries is hazardous gases. trying to stream in various renewable and conventional energy sources. Currently, furnace oil Some heavy metals and trace metals are and natural gas-based power station are working for essential for normal functioning of many biological the production of electricity in Pakistan. However, systems and their deficiency or excess can cause the unpredictable and extraordinary increase in oil many biological disorders [7]. However, the potential prices makes it an expensive and erratic power accumulation of these heavy metals in bio systems source. On the other hand limited reserves of natural through soil, air, and water is one of the major issues gas make it difficult to meet the energy requirement. of recent times [8-9]. In order to check the emission Hence, efforts are being made to explore other of these toxic pollutants, it would be more practical indigenous resources such as coal, hydropower, solar, to know what exactly present in coals of various wind and nuclear energy generation [2]. vicinities across the country.
Coal being an important and most abundant The present study was planned to screen the fossil fuel in Pakistan can play a key role to meet coal of different mines present in Punjab and ever-increasing energy demands of industrial, Baluchistan regions of Pakistan while evaluating agricultural and domestic sectors. According to a their colorific values. The results of the present report published by Renewable and Sustainable investigation may help the extent and nature of Energy Reviews [3], Pakistan ranks 7th in the world pretreatment the coal should undergo before its with around 186 billion tons of coal reserves. Coal application as fuel. Moreover, trace metal analysis being an extremely heterogeneous matrix containing will decide which type of heavy metal exposures organic (C, H, O, and N), inorganic and volatiles miners and engineers can undergo while working
*To whom all correspondence should be addressed. Muhammad Akbar et al., J.Chem.Soc.Pak., Vol. 41, No. 03, 2019 556
with coals of these origins. Total coal reserves of being mined. Investigations show that total coal Pakistan stand at 185.175 billion tonnes with Sindh reserves of Duki-Anambar stands at 80.4 mt. having maximum share of approximately 184.623 Chamalang Coalfields include Mari Bijar, Surghari, billion tonnes. Lunda, Bala Dhaka, Nosham, Bahlol and Kali Chapri areas. Chamalang coalfield includes Kohlu, Barkhan, Experimental and Loralai districts and expands over an area of 500 square miles. Total coal reserves in Chamalang are Study Area estimated to be 100 mt. Coalfield area in Salt Range include Chakwal, Khushab, Jhelum and Mianwali Three areas were selected for coal analysis districts (260 Km2/100.36 miles2). Total coal including Duki, Chamalang and Salt Range. Duki is estimated in this area is 213 mt. Coal samples were located in Loralai District (Zhob Division, randomly taken from different coal mines of Duki, Baluchistan), out of 17 coal seams 15 coal seams are Chamalang and Salt Range (Map 1).
Map 1: Map of Pakistan showing coal sampling areas of Dukki, Chamalang and Salt Range.
Muhammad Akbar et al., J.Chem.Soc.Pak., Vol. 41, No. 03, 2019 557
The coal (ten random samples) collected Accurately weighed 1.0 g of the coal sample was from mining areas Duki (Baluchistan), Chamlang taken in a pre-weighed clean crucible and placed in a (Baluchistan) and Salt Range (Punjab) of Pakistan cold muffle furnace. The sample temperature was were homogenized, desiccated then pulverized into initially raised to 500°C in 1 h then to 750°C in the fine powder and sieved through 250 µm mesh sieve. next hour. Then it was cooled to room temperature in The samples were stored in airtight bags of a desiccator and weighed again to estimate the ash polyethylene before analysis. Analytical grade content. reagents including Copper Sulphate (CuSO4), Potassium Sulphate (K2SO4), Sodium Hydroxide Fixed carbon (NaOH), Barium Chloride (BaCl2), Sulphuric Acid (H2SO4), Nitric Acid (HNO3), Hydrochloric Acid The leftover weight after moisture, volatile (HCl) and Hydrofluoric Acid (HF) were purchased matter and ash was taken as fixed carbon whose from Merck and were used as such without any percentage was calculated by the method of further purification. difference.
Methods Calorific value American Society for Testing Materials (ASTM) guidelines were followed to perform ASTM D5865 standard was followed for the proximate and ultimate analyses of the coal, whereas estimation of calorific value of all coal samples. Ballistic bomb calorimeter was used to investigate Benzoic acid with known calorific value (6.32 kcal/g) calorific value. was used as standard to calibrate Ballistic bomb calorimeter [17]. A known mass (0.5 g) of each Proximate Analysis: Proximate analysis of sample taken in the crucible was placed in the bomb coal includes moisture, ash, volatile matter and fixed calorimeter. Oxygen was filled up to pressure of 25 carbon. Proximate analysis was accomplished bar and the sample was ignited. Heat released as a following the official standard of ASTM D3172, result of combustion reaction was noted by the D3173, D3175, D3176 and D3174 with slight maximum deflection of galvanometer. The energy modifications [10-11]. The fixed carbon was value of the sample material was estimated by quantified by difference method [12-14]. comparing galvanometer deflections for the sample and that for the standard (benzoic acid) and is given Moisture content in the equation:
The moisture contents of all the coal G. meter deflection calibration samples were quantified by following ASTM-D3173 Q standard [15]. In this assay, accurately weighed 1.00 Original weight of sample g of coal was taken in a pre-weighed crucible and placed in a cold muffle furnace. The sample was Its mathematical form is shown in equation 1: heated to 104°C for 1 h to remove the moisture. Then the crucible was cooled to room temperature in a desiccator and weighed again. The %age moisture Qkcalg31 / (1) content was calculated as percentage weight loss. Z
Volatile matter where Q is heat released from sample, θ1 is the The volatile matter of each coal sample was galvanometer deflection without sample, θ3 is the determined using ASTM-D3175 standard [15]. galvanometer deflection with sample, Z is the mass of Accurately weighed amount (1.0 g) of moisture free sample in g and γ is the calibration constant. sample was taken in a pre-weighed crucible with lid Ultimate analysis and heated to 925°C for 7 min in a muffle furnace. The sample was removed before reaching the ignition The Ultimate analysis (carbon, hydrogen, temperature then cooled to room temperature in a nitrogen, sulphur, and Oxygen) of the coal samples desiccator. The volatile matter was calculated as the was conducted according to the ASTM methods percentage weight loss. D3178, D3179 and D3177 [15].
Ash content Carbon and Hydrogen
ASTM- D3174 standard was followed to The carbon and hydrogen contents of coal determine the ash content of each coal sample [16]. samples were determined by Liebig method Muhammad Akbar et al., J.Chem.Soc.Pak., Vol. 41, No. 03, 2019 558
following ASTM- D3178 standards [17]. In this resultant solution was then filtered by decantation method, accurately weighed amount (2.0 g) of coal method while flushing with hot water. Methyl orange sample was taken in a platinum crucible and indicator was added (2-3 drops) into the filtrate combusted in plenty of oxygen at 1300°C in followed by the addition of HCl to neutralize it then combustion train. The gaseous combustion product added additional amount (2.0 mL) of HCl to make were first passed over heated copper oxide and lead solution slightly acidic. The solution was then boiled chromate then led into the absorption train. Copper with subsequent addition of chlorination barium oxide confirms the complete combustion of the solution (10 mL) and kept on stirring for 2 h. The carbon and hydrogen in the coal whereas the lead solution was kept overnight for cooling then filtered chromate acts as absorber for the oxides of sulphur. with dense ashless filter paper. The precipitates were The absorption train contains pre-weighed absorbers washed with hot water till the removal of all chlorine for water and carbon dioxide. The weight gain of ions and shifted to a pre-weighed crucible. The absorbers gives the amount of water and carbon crucible and its contents were heated at low dioxide formed which in turn helps to calculate temperature to ash the filter paper then burnt at 800- percentage of carbon and hydrogen in the sample. 850 °C for 20-40 min in a muffle furnace. After that the crucible was taken out and cooled to room Nitrogen content temperature in a desiccator. The crucible was weighed again. Kjeldahl method (ASTM-D3179 standard) was adopted for the determination of Nitrogen in The total sulphur content of each coal Coal samples. Briefly, 2.0 g of coal sample was taken sample was calculated using the formula given in in a Kjeldahl digestion flask containing H2SO4 (20 equation 3: mL). Then CuSO4 and K2SO4 (1.0 g each) were added as catalysts into the flask. The mixture was AB13.738 boiled and diluted with distilled water (100 mL) and Total sulphur (3) allowed to cool. The mixture was then subjected to C distillation after the addition of 35% (w/v) NaOH. where A is the mass of barium sulphate from the NH3 gas produced was condensed into the receiving flask containing 2% boric acid. The alkaline distillate sample, B is the mass of barium sulphate from the was titrated against 0.1 M HCl using bromocresol blank and C is the mass of sample. green and methyl red indicators. The percentage of nitrogen was calculated as shown in equation 2: Oxygen content
The oxygen content of the coal samples was VNVNVN %100Nitrogen HClHClBKNaOHNaOHNaOH determined by the difference as shown in equation 4: 1.4007W
(2) %100%OxygenCHNSMoistureAsh where VHCl is the volume of standard HCl added into (4) sample flask; VNaOH is the volume of standard NaOH used to titrate sample; NHCl is the normality of HCl; Trace Metal Analysis NNaOH is the normality of NaOH; VBK is the volume of standard NaOH used to titrate 1.0 mL standard HCl There are a number of established methods minus B; B is the volume of standard NaOH used to for trace metal analysis of coal [19-21]. Each coal titrate reagent blank distilled into HCl; 1.4007 is sample (1.0 g) was digested in 40 mL HCl: HNO3: milliequivalent weight of nitrogen × 100; W is HF (1:1:2) mixture by heating on hot plate for 6 h. sample weight in grams. Heating was continued until complete dryness to remove volatile fluorides. Then 5 mL each of HNO3 Sulphur Content and H2O were added and contents were filtered out in 50 mL measuring flask and volume was made up to In order to determine the sulphur content of the mark. coal samples the Eschka method (ASTM-D 3177 standard was adopted [18]. In this assay, 1.0 g of coal Statistical Analysis sample was mixed with 3.0 g Eschka mixture in a porcelain crucible. The resultant mixture was heated All the experiments were conducted in up to 800 °C in muffle furnace for 1-2 h. The crucible triplicate and range of parameters were calculated as was transferred to 100 mL of boiling water and the mean ± SD at 95 % confidence level. Muhammad Akbar et al., J.Chem.Soc.Pak., Vol. 41, No. 03, 2019 559
Results and Discussion
Proximate composition of coal
The proximate composition, particularly moisture, ash, volatile compounds, and fixed carbon influence the coal quality [22]. In general, coals having less moisture and volatile matter, and higher fixed carbon are ranked good quality coals [23]. The mean values of proximate parameters moisture level (%), ash content, volatile matter, and fixed carbon have been plotted in Fig. 1. It is clear from the plotted data Duki coal contained higher water and volatile compounds as compared to other coal samples. The ash content or minerals in Salt range coal was higher than the other two types of coal tested. Similarly, fixed carbon was found to be higher in Chamalang Fig. 2: Average calorific value (kcal/kg) of Duki, coals. The data in fig. indicates that calorific values Chamalang coal (Baluchistan) and Salt of chamalnag coals were higher as compared to that Range coal (Punjab). of Duki and salt range. In this context, Table-1 provides a composition of individual coals samples For Chamalang coal (Table-1), the minimum selected from various coal reserves in Pakistan. values are 1.01±0.02, 6.70±0.57, 34.40±1.42, 33.32±2.51 and 5352±31.09, respectively whereas the maximum values are 5.72±1.28, 23.85±1.34, 45.61±2.27, 52.37±3.67 and 6971±31.69, respectively. The average values are 3.0, 17.63, 38.49, 43.01 and 6125, respectively.
In case of Salt Range coal (Table-1) the minimum values are 1.90±0.08, 17.29±01.35, 22.70±1.44, 24.40±2.50 and 3890±17.45, respectively and the maximum values are 7.03±1.11, 39.30±02.69, 39.04±2.09, 54.40±3.47 and 6098±36.94, respectively while the average values of these parameters are 4.48, 26.38, 32.54, 36.60 and 5094, respectively.
The above stats indicate that the coal belonging to the aforementioned areas of Pakistan is Fig. 1: Average percentage moisture content, ash sub-Bituminous. In addition, it also shows that Salt content, volatile matter and fixed Carbon in Range coal is low in quality as compared the other Duki Coal (Baluchistan), Chamalang Coal two areas. (Baluchistan) and Salt Range Coal (Punjab). Trace metals content of Coal The minimum values for moisture (%), ash (%), volatile matter (%), fixed carbon (%) and Trace metals are known to exert adverse calorific value (KCal/kg) of Duki coal (Table-1) were health effects to the population that is directly in 2.50±0.92, 6.50±0.95, 34.30±1.96, 32.58±1.5, contact with the coal burning or living closer to the 81.90±0.09 and 5082±24.59, respectively. The coal mines, coal deposits, or coal-burning power maximum values of these parameters for Duki coal stations. The estimation of trace metal level in the are 10.89±2.25, 24.27±3.54, 46.40±1.67, 44.60±3.49 coal is therefore very important in order to generate and 6547±29.28 respectively. The average values of baseline data and to plan future strategies to avoid these parameters are 6.61, 14.81, 39.48, 39.08 and any health related implication associated with coal 5867 respectively. burning [10, 24].
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Table-1: Proximate Composition of Duki, Chamalang and Salt Range Coal. Sampling Location Moisture (%) Ash (%) Volatile Matter (%) Fixed Carbon (%) Calorific Value (kcal/kg) DC1 10.89±2.25 9.73±1.58 38.12±2.77 41.28±3.45 6068±56.00 DC2 4.91±0.97 24.27±3.54 34.10±1.94 36.70±2.15 5226±41.05 DC3 9.71±1.58 10.78±2.15 40.77±2.75 38.74±1.94 5832±37.52 DC4 7.84±1.12 22.74±1.36 36.81±3.04 32.58±1.58 5082±24.59 DC5 4.90±0.81 10.70±1.49 39.80±2.51 44.60±3.49 6245±36.12 DC6 10.80±2.47 15.30±1.80 34.30±1.96 39.60±2.56 5436±31.28 DC7 7.20±1.36 6.50±0.95 42.50±3.57 43.80±2.13 6393±46.70 DC8 2.50±0.92 18.40±2.04 41.4±3.01 37.70±2.05 6547±29.28 DC9 4.80±1.02 14.70±1.45 40.60±2.88 39.90±2.45 5890±39.51 DC10 2.60±0.56 15.01±1.87 46.40±1.67 35.90±1.98 5955±19.58 Mean 6.61 14.81 39.48 39.08 5867 CC1 1.92±0.09 14.0±1.61 37.68±1.91 46.40±3.44 6327±22.57 CC2 1.90±0.04 12.51±0.91 38.65±2.36 46.91±2.57 6444±30.56 CC3 4.01±1.00 18.80±2.01 37.20±1.73 39.99±2.12 5742±36.17 CC4 3.80±0.83 21.22±2.34 36.70±2.01 38.30±2.24 5550±22.25 CC5 2.71±0.07 9.61±1.33 38.44±1.55 49.23±3.88 6539±28.37 CC6 1.82±0.05 10.80±1.08 39.61±1.93 52.37±3.67 6971±31.69 CC7 4.31±0.84 16.03±2.34 36.60±2.00 42.98±3.24 5967±38.12 CC8 5.72±1.28 20.01±2.85 34.40±1.42 39.89±2.59 5531±28.21 CC9 1.01±0.02 6.70±0.57 45.61±2.27 40.69±3.61 6825±24.77 CC10 2.80±0.06 23.85±1.34 40.03±1.91 33.32±2.51 5352±31.09 Mean 3.0 17.63 38.49 43.01 6125 SRC1 5.82±1.05 22.75±2.15 32.39±1.74 39.04±1.99 5421±20.89 SRC2 3.96±0.71 23.76±1.78 35.76±2.22 36.52±1.67 5326±18.76 SRC3 1.90±0.08 17.29±1.35 26.40±1.85 54.40±3.47 6098±36.94 SRC4 7.92±2.04 23.52±2.77 33.66±2.05 34.90±2.11 5023±28.25 SRC5 3.20±0.69 26.73±1.95 36.40±1.11 33.67±2.22 5117±22.29 SRC6 2.97±0.51 33.66±2.68 39.04±2.09 24.40±2.50 4491±21.98 SRC7 4.01±0.83 35.21±1.98 30.31±1.15 30.47±2.43 4368±25.53 SRC8 5.01±1.05 23.76±1.54 35.02±1.58 36.21±2.86 5250±30.25 SRC9 7.03±1.11 39.30±2.69 22.70±1.44 30.97±1.79 3890±17.45 SRC10 3.01±0.82 17.82±1.08 33.78±1.96 45.40±3.29 5958±05.38 Mean 4.48 26.38 32.54 36.60 5094 DC: Duki Coal, CC: Camalang Coal, SRC: Salt Range Coal
Table-2: Trace metal analysis of of Duki, Chamalang and Salt Range Coal. Sampling Co (ppm) Cr (ppm) Cu (ppm) Ni (ppm) Pb (ppm) Zn (ppm) Cd (ppm) location (Mean±SD) (Mean±SD) (Mean±SD) (Mean±SD) (Mean±SD) (Mean±SD) (Mean±SD) DC1 3.0±0.85 19.0±2.05 14.0±2.15 5.98±1.25 1.40±0.05 4.86±0.43 0.15±0.04 DC2 4.60±0.94 13.85±1.86 11.35±0.95 14.45±2.24 1.12±0.24 5.75±0.09 0.20±0.06 DC3 2.55±0.51 4.90±1.57 2.15±0.08 12.60±1.61 0.95±0.01 18.62±2.03 0.05±0.01 DC4 12.0±1.24 42.3±3.56 20.0±2.47 8.95±2.15 1.86±0.06 5.90±0.54 0.09±0.02 DC5 7.41±0.74 22.35±3.15 18.42±2.25 13.60±1.10 1.95±0.08 12.87±1.54 0.12±0.05 DC6 7.20±0.98 25.40±2.25 15.90±1.53 13.05±2.10 1.89±0.12 7.90±1.06 0.16±0.04 DC7 3.30±0.57 7.05±1.11 5.25±1.11 13.25±1.17 2.45±0.05 9.94±2.10 0.07±0.01 DC8 4.40±1.01 7.90±125 9.95±3.12 18.45±2.26 2.83±0.10 11.76±2.31 0.10±0.01 DC9 15.80±2.56 43.05±3.58 36.55±3.31 21.05±1.25 1.03±0.01 12.89±1.95 0.08±0.02 DC10 13.95±1.24 37.75±3.56 50.65±4.51 14.80±1.29 3.89±0.33 7.56±1.34 0.13±0.03 Mean 7.42 22.36 18.42 13.62 1.94 9.80 0.115 CC1 11.35±1.25 46.60±4.18 32.95±3.50 26.60±3.16 2.67±0.35 23.67±3.45 0.09±0.01 CC2 9.95±1.09 26.3±2.74 18.65±2.58 19.5±1.55 4.23±0.48 12.89±2.15 0.25±0.07 CC3 4.55±0.68 6.30±0.57 12.3±1.47 16.1±1.24 3.95±0.25 23.12±3.33 0.17±0.03 CC4 8.55±1.28 44.55±3.88 33.55±3.11 19.90±2.47 3.90±1.0 7.98±1.17 0.12±0.03 CC5 3.00±0.25 7.01±1.02 16.95±1.59 6.12±1.05 1.35±0.05 15.87±2.49 0.05±0.01 CC6 19.85±2.24 5.55±0.54 49.75±2.99 29.3±3.28 2.24±0.19 11.76±1.29 0.08±0.01 CC7 21.55±2.57 31.95±3.25 36.7±3.51 25.95±2.04 3.78±0.67 8.94±1.56 0.14±0.03 CC8 10.75±1.25 32.9±4.11 18.5±2.22 14.6±1.42 3.09±0.25 - 0.09±0.01 CC9 11.19±1.02 25.14±1.28 27.42±1.45 19.76±2.22 3.15±0.39 5.89±0.97 0.15±0.02 CC10 8.56±1.58 22.96±2.38 19.45±2.38 12.03±1.05 2.74±0.11 4.98±0.04 0.07±0.01 Mean 10.93 24.93 26.62 18.99 3.11 13.31 0.12 SRC1 5.0±0.62 20.5±2.82 11.1±2.14 11.4±1.89 10.3 ±1.59 11.1±1.12 0.14±0.02 SRC2 13.45±1.09 14.3±2.02 13.8±1.54 12.9±2.04 12.1±1.26 8.75±2.01 0.09±0.01 SRC3 21.2±2.14 59.8±3.69 37.25±2.45 41.8±3.33 3.91±0.14 33.12±3.07 0.06±0.01 SRC4 5.05±0.57 20.5±2.15 13.6±3.26 21.05±2.73 3.84±0.58 12.98±1.12 0.12±0.03 SRC5 5.85±1.02 22.0±2.22 8.9±2.14 14.25±2.21 0.78±0.01 22.45±3.13 0.17±0.03 SRC6 16.75±2.50 43.8±4.53 35.45±3.65 35.3±2.56 4.07±0.26 16.90±2.45 0.14±0.01 SRC7 9.45±1.47 36.55±3.21 25.85±3.33 23.15±3.53 4.56±0.17 32.21±3.37 0.06±0.01 SRC8 21.05±3.05 39.1±2.58 18.15±2.25 21.35±2.25 2.98±0.34 10.76±1.12 0.08±0.02 SRC9 10.65±1.25 46.15±3.36 23.35±3.26 36.55±2.14 4.09±0.28 9.95±1.16 0.16±0.06 SRC10 3.65±0.69 8.75±1.33 5.7±0.86 7.85±1.21 12.75±1.49 8.43±0.09 0.06±0.01 Mean 11.21 31.14 19.31 22.56 5.94 16.665 0.108
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In this study, trace metals including Co, Cr, investigation of various coal blends and state of the Cu, Ni, Pb, Zn, and Cd were investigated in coal art heavy metal mitigation strategies. samples from Duki, Chamalang and Salt Range and results are shown in Fig. 3 (Table-2). The trace metal Table-3: Average values for trace elements in content in Duki coal ranged from 2.55±0.51 to international coals. International coal average Pakistani coal average 15.80±2.56 for cobalt, 4.901.57± to 43.05±3.58 for Element value (mg/kg)[25] range (mg/kg) chromium, 2.15±0.08 to 36.55±3.31 for copper, Arsenic (As) 2.69 0.36–9.8 5.98±1.25 to 21.05±1.25 for nickel, 0.95±0.01 to Boron (B) 47 11–123 Beryllium (Be) 1.0 0.1–2.0 3.89±0.33 for lead, 4.86±0.43 to 18.62±2.03 for zinc Cadmium (Cd) 0.093 0.01–0.19 and 0.05±0.01 to 0.20±0.06 for cadmium. Trace Cobalt (Co) 4.5 1.2–7.8 metal values of Duki, Chamalang and Salt Range are Mercury (Hg) 0.091 0.03–0.19 Lead (Pb) 7.0 1.1–22 shown in Table 2. Selenium (Se) 2.15 0.15–5.0 Chromium (Cr) 17.6 2.9–34 Copper (Cu) 10.8 1.8–20 Manganese 40 8–93 (Mn) Nickel (Ni) 11.1 1.5–21 Zinc (Zn) 12.7 5.1–18 Fluorine (F) 120 15–305 Chlorine (Cl) 440 25–1420
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