Thesis (Master)--İzmir Institute of Technology, İzmir, 2005. / Keywords: Mercury, atomic absorption spectrometry, gold, amalgamation, cold vapor. Includes bibliographical references (leaves 48-51).

This thesis examines historical and contemporary artisanal and small-scale gold mining (ASGM) in Kadoma-Chakari, Zimbabwe in order to identify effective strategies to reduce mercury loss and exposure and to increase miners’ incomes by improving gold recoveries. Cyanidation of mercury-rich tailings and the use of nitric acid to leach mercury from cathode sludge and amalgams are identified as significant pathways for losses of mercury into the environment in Zimbabwe. Indirect evidence suggests that as much as 90% of the mercury contained in amalgamation tailings at mills in Kadoma-Chakari is dissolved during passive vat cyanidation. Mercury traps placed after copper amalgamation plates and centrifuges could reduce the amount of mercury subjected to cyanidation, but mercury can be kept out of cyanidation circuits altogether by replacing whole ore amalgamation with vinyl loop carpets. The optimal cyanide concentration for passive vat leaching is between 0.1 to 0.15%. Better management of nitric acid waste solutions can also significantly reduce mercury losses. The current political and socio-economic crisis significantly limits the effectiveness of ASGM programs in Zimbabwe. Nevertheless, strategies for more effective management of ASGM interventions are suggested by a review of the history of didactic theatre (Theatre for Development) in Africa. Theatre used as an awareness building tool is exemplified by “Nakai”, a drama produced in Kadoma-Chakari to increase knowledge of the hazards of mercury use. Theatre can also be a means to ensure horizontal communication between donors and project beneficiaries if it is used to stimulate discussions that give communities a real voice in development programs. It is proposed that community participation in project design, implementation and evaluation increases the likelihood of project success and sustainability because community-identified problems and solutions are more realistic than those defined by donors, and because community “buy in” and ownership increases pressure on project administrators to deliver the services communities need.

This thesis examines historical and contemporary artisanal and small-scale gold mining (ASGM) in Kadoma-Chakari, Zimbabwe in order to identify effective strategies to reduce mercury loss and exposure and to increase miners’ incomes by improving gold recoveries. Cyanidation of mercury-rich tailings and the use of nitric acid to leach mercury from cathode sludge and amalgams are identified as significant pathways for losses of mercury into the environment in Zimbabwe. Indirect evidence suggests that as much as 90% of the mercury contained in amalgamation tailings at mills in Kadoma-Chakari is dissolved during passive vat cyanidation. Mercury traps placed after copper amalgamation plates and centrifuges could reduce the amount of mercury subjected to cyanidation, but mercury can be kept out of cyanidation circuits altogether by replacing whole ore amalgamation with vinyl loop carpets. The optimal cyanide concentration for passive vat leaching is between 0.1 to 0.15%. Better management of nitric acid waste solutions can also significantly reduce mercury losses. The current political and socio-economic crisis significantly limits the effectiveness of ASGM programs in Zimbabwe. Nevertheless, strategies for more effective management of ASGM interventions are suggested by a review of the history of didactic theatre (Theatre for Development) in Africa. Theatre used as an awareness building tool is exemplified by “Nakai”, a drama produced in Kadoma-Chakari to increase knowledge of the hazards of mercury use. Theatre can also be a means to ensure horizontal communication between donors and project beneficiaries if it is used to stimulate discussions that give communities a real voice in development programs. It is proposed that community participation in project design, implementation and evaluation increases the likelihood of project success and sustainability because community-identified problems and solutions are more realistic than those defined by donors, and because community “buy in” and ownership increases pressure on project administrators to deliver the services communities need.

This thesis examines historical and contemporary artisanal and small-scale gold mining (ASGM) in Kadoma-Chakari, Zimbabwe in order to identify effective strategies to reduce mercury loss and exposure and to increase miners’ incomes by improving gold recoveries. Cyanidation of mercury-rich tailings and the use of nitric acid to leach mercury from cathode sludge and amalgams are identified as significant pathways for losses of mercury into the environment in Zimbabwe. Indirect evidence suggests that as much as 90% of the mercury contained in amalgamation tailings at mills in Kadoma-Chakari is dissolved during passive vat cyanidation. Mercury traps placed after copper amalgamation plates and centrifuges could reduce the amount of mercury subjected to cyanidation, but mercury can be kept out of cyanidation circuits altogether by replacing whole ore amalgamation with vinyl loop carpets. The optimal cyanide concentration for passive vat leaching is between 0.1 to 0.15%. Better management of nitric acid waste solutions can also significantly reduce mercury losses. The current political and socio-economic crisis significantly limits the effectiveness of ASGM programs in Zimbabwe. Nevertheless, strategies for more effective management of ASGM interventions are suggested by a review of the history of didactic theatre (Theatre for Development) in Africa. Theatre used as an awareness building tool is exemplified by “Nakai”, a drama produced in Kadoma-Chakari to increase knowledge of the hazards of mercury use. Theatre can also be a means to ensure horizontal communication between donors and project beneficiaries if it is used to stimulate discussions that give communities a real voice in development programs. It is proposed that community participation in project design, implementation and evaluation increases the likelihood of project success and sustainability because community-identified problems and solutions are more realistic than those defined by donors, and because community “buy in” and ownership increases pressure on project administrators to deliver the services communities need. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate