about us | careers | terms & conditions | intranet | extranet | sitemap | contact us
   
Skip Navigation Links
Home
Skip Navigation Links
Knowledge Hub
Skip Navigation Links
Research
Skip Navigation Links
Resources & Tools
Skip Navigation Links
Learning
Skip Navigation Links
Events
Skip Navigation Links
Symposium
Skip Navigation Links
News & Media
Skip Navigation Links
FET Water
Skip Navigation Links
SCM
Login | Register
Go Search
     
A detailed acid base accounting study of the coal-bearing Karoo formations in the Waterberg coalfield
Expanded Title:The large resource base coal zones of the Waterberg Coalfield, located in the Limpopo Province, will enable the mining of coal in this area and will continue into the future. As the demand for energy in South Africa increases in the coming years, the coal produced from this area will prove essential. The main aim of the study was to identify the potential of acid generation from the overburden, interburden and plant discard that will be removed and placed on the discard dumps, and possibly used as backfill material. Acid Base Accounting (ABA) is used as a prediction tool to determine the acid potential of the lithological units. This aim was met via four objectives: 1. To determine the acid-base potential of all the different geological layers. 2. To determine the best methods of how to handle these spoils and discards in order to minimize the risk of acid generation. 3. If underground mining methods will be practised, what mining methods will be best to minimize the risk of acid generation? This was not investigated as too little information is available for such future mining. 4. Identify which further research need to be undertaken concerning the impact of mining of the Waterberg coal reserves on water resources. The ABA analyses of overburden indicated a dominantly neutralising potential, as well as an acidic potential for the shale units on top of the coal. The samples indicated non-acid producing potentials and some with neutralising potentials. The cumulative mass of sulphate produced, indicated that the overburden samples do not continue to produce sulphate, but rather reaches a constant rate where sulphide is produced. During the kinetic tests, the results for calcium and alkalinity were relatively high. The relatively low calcium values indicate that carbonates are immediately available and demonstrate the balance between the released alkalinity and the acidity generated. If the balance between the alkalinity and the acidity stays positive, the system will not acidify. The interburden contained both acidic and neutralising potentials. Mudstone, shale and calcrete layers indicated a neutralising potential, while sandstone had a relatively high acid generating potential. With prolonged exposure the system would acidify as sulphate is released into the system. Calcium and alkalinity results showed high calcium values, with relatively low alkalinity for the interburden. The high calcium values indicate the availability of carbonates, whereas in this case the carbonates are not immediately available. The plant discards consist of unwanted material that remains after coal separation, also known as composite samples. The different density composite samples were analysed and indicated that they all have a high potential to produce acid. The report presents management options for overburden, interburden, ash, spoils, and plant discards.
Date Published:01/11/2014
Document Type:Research Report
Document Subjects:Mine water - Mine water treatment
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:2142/1/14
ISBN No:978-1-4312-0599-8
Authors:Deysel L; MacDonald N; Aphane V; Vermeulen PD
Project No:K5/2142
Originator:WRC
Organizations:Institute for Ground water Studies; University of Free State, department of Agricultural Economics
Document Size:17 829 KB
Copyright 2015 - Water Research Commission Designed By: Ceenex