English: South Africa has several coal mines of which promised economic wealth since the 1700, however the exploitation of this commodity has a negative effect to the environment. Mining operations are a source of Acid Mine Drainage (AMD) in South Africa therefore salt loading and acidic conditions are of concern. Although lab methods such as Acid-Base Accounting (ABA) are used to predict the impact and effects of AMD, it is still difficult to predict its rate. The importance of laboratory analysis is to give the best and worst case scenario of the area, provided that the samples are representative of the area investigated. This thesis is conducted to note the difference between South African and Australian Laboratory methods in determining the potential and existing acidity of the samples. Furthermore, AMD is predicted using ABA methods for the Middelburg area. South Africa uses similar ABA laboratory guidelines as USA and Europe while Australia uses its own guidelines that are modified from time to time. After the comparisons of the methods were evaluated, the Australia‘s versus the South African results showed a very good correlation. However the Ca percentage from the ICP results had a lower correlation compared to other cations in the Actual Acidity Method. The KCl and NaOH used in the Australian Actual Acidity Method either displays the Ca as double or half of the South African ICP results. However, both countries‘ Actual and Potential Acidity Methods are comparable. The Australia‘s Neutralising Potential Method is derived from lime analysis disciples and can be an overestimate of the Neutralising Capacity. Whether the methods and results of Neutralising Capacity can be compared or not, is inconclusive. Other ABA tests have to be done on the same samples to verify if personal, analytical or instrumental error was significant. To achieve another aim of this thesis, The IGS was approached by Middelburg mine services to update the 2006 groundwater model at Goedehoop, Hartebeesfontein, Bankfontein and Klipfontein Collieries. At a later stage, Acid-Base Accounting (ABA) methods were requested for AMD prediction. The aim of the project was to do groundwater assessment of the collieries and predict future impacts of AMD. The locality of the investigated area is in the Middelburg, which falls in the central Highveld of the Mpumalanga province in South Africa. Open-cast coal mining is in operation at Klipfontein, Hartebeesfontein and Goedehoop. Klipfontein is along south of the Vaalbankspruit while Hartebeesfontein and Goedehoop spreads north of the Spookspruit. The area is in the Karoo Supergroup which underlines two thirds of the Republic of South Africa with typical rocks like sandstone, mudstone and shale. About 4.7 % of the representative samples from the Middelburg Collieries showed a Net Neutralizing Potential in the Static test method whereas Kinetic tests results proved that only a handful of the samples had a low salt load and a limited buffering capacity. In conclusion, the representative samples showed the investigated Middelburg Collieries had high-medium risk of acid-generation upon oxidation. With the prediction of AMD done, control measures can be put in place. The primary objective of AMD treatment is to remove metals (i.e. sulphides, hydroxides and carbonates) and raise the pH to alkalinity. Passive or Active treatments could be used to remedy the area. The deteriorated water quality caused by the coal mining area could be remediated and released into the Upper Olifants river catchment.
Afrikaans: Suid-Afrika het verskeie steenkoolmyne wat sedert die 1700's ekonomiese welvaart belowe, maar die ontginning van hierdie kommoditeit het 'n negatiewe uitwerking op die omgewing. Mynboubedrywighede is 'n bron van suur myndreinering ("Acid Mine Drainage" - AMD) in Suid-Afrika, en daarom is sout- en suurtoestande van kommer. Hoewel laboratoriummetodes soos Suur-Basis-Rekening ("Acid-Base Accounting" - ABA) gebruik word om die impak en gevolge van AMD te voorspel, is dit steeds moeilik om die tempo te voorspel. Die belangrikheid van laboratorium-analise is om die beste en slegste scenario vir die gebied te verkaf, gegewe dat die monsters verteenwoordigend is van die gebied wat ondersoek word. Hierdie ondersoek is onderneem om die verskil tussen Suid-Afrikaanse en Australiese laboratoriummetodes aan te dui in die bepaling van die potensiële en bestaande suurgehalte van die monsters. Verder is AMD voorspel deur gebruik te maak van ABA-metodes vir die Middelburg-omgewing. Suid-Afrika gebruik soortgelyke ABA laboratoriumriglyne as die VSA en Europa, terwyl Australië sy eie riglyne gebruik wat van tyd tot tyd verander. Na afloop van die vergelykings van die metodes wat geëvalueer is, toon die Australiëse en Suid-Afrikaanse resultate 'n baie goeie korrelasie. Maar die Ca-persentasie van die ICP resultate het 'n laer korrelasie in vergelyking met ander katione in die Werklike Suurheidsmetode (Actual Acidity Method). Die KCl en NaOH wat gebruik is in die Australiese Werklike Suurheidsmetode gee óf die Ca as dubbel óf die helfte van die Suid-Afrikaanse ICP resultate weer. Maar, beide lande se werklike en potensiële suurheidsmetodes is vergelykbaar. Australië se Neutraliseringspotensiaalmetode is afgelei van die Kalk Analise Dissipline en kan die Neutraliseringsvermoë oorskat. Of die metodes en resultate van die Neutralisingskapasiteit vergelyk kan word of nie, is onoortuigend. Verdere ABA-toetse moet gedoen word op dieselfde monsters om te bepaal of persoonlike, analitiese of instrumentale fout van deurslaggewende belang was. Om 'n ander doel van hierdie ondersoek te bereik, is die IGS deur Middelburg myndienste genader om die 2006 grondwatermodel by Goedehoop, Hartebeesfontein, Bankfontein en Klipfontein Collieries, by te werk. Op 'n latere stadium is suur-basis-Rekening (ABA) metodes gevra vir AMD voorspelling. Die doel van die projek was om grondwaterassessering van die steenkoolmyne te doen en die toekomstige impak van AMD te voorspel. Die ligging van die ondersoekgebied is Middelburg, wat in die sentrale Hoëveld van die Mpumalanga-provinsie in Suid-Afrika val. Sogenaamde ―Open-cast‖ steenkoolmyning is in werking op Klipfontein, Hartebeesfontein en Goedehoop. Klipfontein strek langs die suide van die Vaalbankspruit terwyl Hartebeesfontein en Goedehoop noord van die Spookspruit geleë is. Die gebied is in die Karoo Supergroep, wat onderliggend is aan 2 / 3 van die Republiek van Suid-Afrika, met tipiese gesteentes soos sandsteen, modderklip en skalie. Sowat 4,7% van die verteenwoordigende monsters van die Middelburg-Collieries toon 'n netto neutraliseringspotensiaal in die statiese toetsmetode, terwyl Kinetiese toetsresultate bewys het dat slegs 'n handjievol van die monsters 'n lae soutgehalte en 'n beperkte bufferkapasiteit het. Ten slotte, die verteenwoordigende monsters uit die ondersoekte Middelburg Collieries het getoon dat daar 'n hoë-medium risiko van suur-generasie tydens oksidasie is. Met die voorspelling van AMD afgehandel, kan kontrolemaatreëls in plek gestel word. Die primêre doel van AMD behandeling is om metale te verwyder (m.a.w. sulfiede, hidroksiede en karbonate) en die pH na alkaliniteit te verhoog. Aktiewe of passiewe behandelings kan gebruik word om die gebied te herstel. Die besoedeling van die water wat veroorsaak word deur die steenkoolmyn-area kan herstel en vrygelaat word in die Bo-Olifantsrivier-opvanggebied.