بررسی‌های آزمایشگاهی با روش aba اصلاح شده برای ارزیابی پتانسیل تولید آلودگی از باطله‌های ذخایر سولفیدی با میزبان کربناته و مقایسه با رویکرد کانی‌شناسی

از اصلی ترین مشکلات در ارتباط با باطله های معدنی، بحث تشکیل پساب های معدنی به‌صورت اسیدی تا قلیایی و انتقال فلزات سمی در مناطق پایین دست است. بنابراین ارزیابی پتانسیل آلودگی این نوع باطله ها امری پر واضح است. پژوهش حاضر با هدف پایش غلظت فلزات سنگین و ارزیابی پتانسیل تولید یا خنثی سازی آلودگی در باطله های سرب و روی تیپ سولفیدی با میزبان کربناتی در معدن انگوران است. در این راستا، تعداد 47 نمونه از بخش های مختلف سطح دمپ باطله برداشت و غلظت عناصر s، ca و mg و هم‌چنین فلزات سنگین مانند as، cd، cr، cu، ni، pb و zn به‌وسیلۀ روش icpms تجزیه شد. از شاخص آلودگی به منظور پهنه‌ندی ریسک آلودگی کل فلزات سنگین استفاده شد و سپس از روش استاتیکی اسید باز اصلاح شده برای ارزیابی پتانسیل آلودگی استفاده و نتایج با روش کریجینگ مدل سازی شد. با توجه به مقادیر کم سولفور کل (کم‌تر از 1%)، تمام نمونه ها پتانسیل خنثی سازی خالص بالایی با دامنه بین 990-49 کیلوگرم کربنات کلسیم بر تن از خود نشان دادند. به منظور تعیین منشا خنثی سازی و تفسیر بهتر نتایج استاتیکی از روی‌کرد کانی شناسی (مجموع غلظت mg+ca) استفاده شد. نتایج روی‌کرد کانی شناسی با یک هم‌بستگی بالا (0.99=r)با روی‌کرد آزمایشگاهی، کانی کلسیت را به‌عنوان منبع اصلی خنثی ساز معرفی کرد ه‌منظور اعتبارسنجی نتایج، تجزیه xrd روی 4 نمونه انجام و حضور کانی کلسیت به‌عنوان فراوانترین و بارزترین منبع خنثی سازی تایید شد.

Laboratory Studies with a Modified ABA Method for Evaluation of Pollution Potential from Carbonate Hosted Sulfide Waste Dumps in Comparison to Mineralogical Approach

Introduction Sulfidecarbonate deposit is a term, which comprises a series of sulfide minerals such as ZnPb ore minerals, mainly considered as related to weathering of ZnPb sulfide concentrations and influence in sedimentary hosts (carbonate). There are more than 350 ZnPb deposits located in Iran, including worldclass deposits such as Angouran, Mehdiabad and Irankouh. Due to the mining activity of these deposits, it creates a significant amount of mine waste that releases of these wastes in the environment causing severe problems. One of the main problems is the formation of Acid Mine Drainage (AMD). AMD is produced by oxidation of sulphide minerals, particularly pyrite (FeS2) in waste dump. Due to low pH and the ability to dissolve metals and other compounds, it can host a number of environmental problems. A phenomenon known as natural or alkaline mine drainage (NAMD) occurs at high pH values ​​when the neutralizing minerals are significantly present in the mine waste or when the oxidation of the sulfide minerals is poor. However, the metals and cationic species, such as Cu, Pb and Cd, are more soluble at low pH. In contrast, elements that form anionic species, such as Se, Cr, V, and Mo, tend to be more soluble at high pH and Ni, Zn, Co, As, and Sb, are soluble at nearneutral pH, and can potentially contaminate mine effluents, even without acidic conditions. Therefore Acid or Neutralization potential (AP NP) of waste dump is significantly affects on the composition, transfers and fates of contaminations transmitted from waste dump. The aim of this study was to monitoring heavy metals concentrations and assessments of pollution potential of waste dumps in Anguran mine by static method and has been compared by mineralogical approach.Material and methodsThe Angouran ZnPb deposit is located in the 135 kilometers southwest part of Zanjan Province, NW Iran. This area belongs to the northwestern part of the SanandajSirjan Zone, a metamorphic belt related to the Zagros orogeny. Angouran mine is one of the most important carbonate hosted ZnPb deposits in Iran that mining activity has been created a significant amount of waste dump in around pit. To achieve the goals, the 47 samples taken from different surficial parts of the waste dump were analyzed by using the ICPMS method to determine the concentration of elements and heavy metals. These elements and metals includes: Ca, Mg, S and As, Cd, Cr, Cu, Ni, Pb, Zn. The pollution index (PI) were modeled for heavy metal contamination risk zoning then modified Acid Base Accounting (ABA) static method was used to evaluate of acid and neutralization potential (AP NP) of the waste dump samples and the results were modeled by Kriging method. At the end, mineralogical approach (Mg + Ca concentration) was used to determine the source of neutralization and to better interpret the static results.Results and discussionThe results of contamination index showed that zinc, arsenic and cadmium had the highest average contamination index (18.89, 12.13 and 5.8, respectively) and the trend of total metal changes in the region as Zn> As> Cd> Pb > Ni> Cr> Cu was rated.Datas measured in modified ABA method were modeled in 2D maps using the Kiriging method. Due to the low total sulfur content (less than 1%), all of the samples were Net Neutralization Potential (NNP) with a range of 49 990 kg calcium carbonate per ton, and the study area was classified into three neutralization potential (NP), High (NP) and Very High (NP) levels. The mineralogical approach (Mg + Ca concentration) was used as a useful tool for better interpretation of modified ABA results and determines the neutralizing source. Mineralogical approach results indicate that calcite species are the main source of neutralization and have high correlation coefficient (R = 0.99) with the modified ABA method. In order to validate the results, the presence of mineral calcite was confirmed by XRD analysis on 4 samples.Assessment of AP and NP of sulfide - carbonate waste dump in this research can be used as a basis model for other similar mines to control environmental problems and to identify the behavior and to transfer heavy metals in mine drainage in the future. Mineralogical approach results show that neutralizing potential and neutralizing source can be obtained without using expensive mineralogy analyses in this type of carbonatesulfide deposit