Assessing the acidic potential of waste rock in the Akara gold mine, Thailand

Abstract

Acid mine drainage (AMD) is the environmental issue that generates the greatest public concern regarding the mining industry. Thus, characterization of mine waste rock according to acid generation potential is necessary for mining operations to ensure proper waste rock storage and to avoid future adverse environmental effects. Therefore, this study was conducted to estimate the potential of AMD generation in the largest operating gold mine in Thailand by using acid base accounting and net acid generation tests. Representative samples of six types of waste rock classified by mining geologists for mineral processing and waste dumping were collected for this study: volcanic clastic, porphyritic andesite, andesite, silicified tuff, silicified lapilli tuff, and sheared tuff. Under various conditions, experimental results indicate that only silicified lapilli tuff and shear tuff are potentially acid-forming materials. The results indicate that AMD generation may possibly occur a long time after mine closure due to the lag time of the dissolution of acid-neutralizing sources. Acidic generation from some waste rocks may occur in the future based on environmental conditions, particularly the oxidation of sulphide minerals by the combination of oxygen and water. Therefore, a proper design for waste rock dumping and storage is necessary to reduce the risk of AMD generation in future. It is advisable to install a surface management system to control the overland flow direction away from the waste dump area and tailing storage facility and to install a second water storage pond next to the main storage pond to store the spilled water during storms and the rainy season. A water quality monitoring plan that focuses on disturbed areas such as water storage ponds and mine pits should be put in place.

Mineralogical and Geochemical Characteristics of the H-Pit of the Chatree Gold Deposit, Central Thailand: A Case Study for Assessment of Acid Rock Drainage and Heavy Metal Sources

“…It is also noticed that the hanging wall zone consisting of lithic-rich fiamme breccia is considered a permeable rock, which can have board zones of hydrothermal alteration [6]. The result of this study is consistent with the data in Changul et al [14], who reported that PAF materials are identified in the silicified lapilli tuff and sheared tuff units in the C-H pit (H ore lens is a part of the C-H pit) at the Chatree mine. As the tuff units are indicated to occur in the northwestern part of the C-H pit, which corresponds to the distribution of the lithic-rich fiamme breccia unit in the hanging wall zone, the tuff units classified as PAF in Changul et al [14] are equivalent to the PAF rocks characterized in this study.…”

“…Several published papers assess the environmental aspects of the Chatree mine [8,13,14,16,17,47], and these studies discuss and conclude a wide range of potential environmental issues at the Chatree, including potential AMD generation in the future. However, the data produced in previous studies are based principally on samples collected either from the waste dump or tailing sites where mixed materials are stored.…”

“…The study used static tests to evaluate the acid-forming potential (AFP) for ARD classification [4,38]. The static test of acid-base accounting (ABA) was assessed by determining the maximum potential acidity (MPA), acid neutralizing capacity (ANC), net acid-producing potential (NAPP), net acid generation (NAG), paste pH, and acid potential ratio (APR) [14,39]. The MPA was investigated from the total sulfur contents, which were detected using a LECO 628 series (CHNS determinator) at the Scientific and Technological Research Equipment Center (STREC), Chulalongkorn University, Thailand, and the MPA values were obtained from the sulfur contents multiplied by 30.6 [5,40].…”

“…Several environmental studies have been undertaken at the Chatree mine area to assess potential AMD generation and heavy metal contamination in surface and ground waters, soil, tailing, and dumped waste rocks [8,[13][14][15][16][17]. These studies conducted many tests on various waste and tailing materials and predicted potential environmental risks in the future in the mine area.…”

The Acid-Base Accounting (ABA) of Overburden Rock to Predict Acid Mine Water in Kasai Coal Mining, Indonesia

“…The ABA is claimed as the first technology available to predict the quantity of acid-producing materials prior to mining. With the enactment of the Surface Mining Control and Reclamation Act of 1977 (SMCRA) in the USA, ABA in 1977 and the 8 th International Conference on Acid Rock Drainage, International Network for Acid Prevention, June 2009, Skelleftea, Sweden, ABA has become widely adopted as a method to predict post-mining drainage quality through overburden chemistry analysis 6,7 ABA tests quantify the balance net acid producing potential (NAPP) between potentially acidgenerating potential (MPA), particularly the oxidation of sulfide materials, and acid neutralizing capacity (ANC) in a sample, such as the dissolution of alkaline, carbonates, displacement of exchangeable bases and weathering of silicate 8,9 . The ABA parameters are described below: a.…”