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.It was observed that the in-stope heat load generated, per ton mined, would vary considerably for the different layouts.This can be explained in terms of face/gully utilisation, the heat load due to the ventilated face/gully length, the related exposed hot rock and the effect of backfill.The heat loads of dip pillar underhand and overhand scenarios were relatively low while those ascribed to the down dip scenario were generally higher.This stresses the importance of face utilisation and supports the view that higher stope advance rates should improve the effectiveness of ventilation and cooling systems.Detailed lists of criteria were used to judge the merits of the different layouts qualitatively.Weighting factors were set to each criteria and each layout was scored through consensus with deep mine ventilation specialists and practitioners.In terms of this comparison, the dip-pillar down-dip mining layout fared better than the others.The dip-pillar breast layouts fared best in terms of escape and rescue considerations, while the strike-pillar layout offered the best advantages in terms of development and multi-blasts needs.However, the four layouts were grouped fairly closely with 18 percentage points separating the best from the worst.Sensitivity studies on the effect of backfill showed that the stope heat load per unit ton mined increased by 30 percent without backfill [irrespective of the layout examined].However, through water drainage, backfill has the potential to create a heat load if the slurry is allowed to arrive hotter than the desired stope temperature.This effect can be relatively simply reversed by cooling the backfill prior to placing it.New finite-difference models for predicting the transient cooling effects of cold water in stopes are now systematically leading to important observations.One of these is that the cooling optimum approach for stopes in very hot rock will require the supply of relatively cold ventilation [with coolers at stope entrance], the use of high efficiency in-stope air coolers, the use of cold service water and modest quantities of free water [possibly 30 minutes before personnel re-enter].Although this paper is mainly concerned with the micro-level [in-stope] environment and considerations, there are two important observations to note on the macro-level.Firstly, the contribution of in-stope heat to the total mine heat load is less than that of the intake tunnelling [for all layouts considered].This means that, for these ultra-deep mines, the air conditioning energy balances of the stopes are less than that of the intake system.Secondly, the total mine-wide costs of owning and operating the ventilation and cooling systems vary by about 20 percent for the different layouts, with the strike-pillar breast mining the highest and dip-pillar overhand breast mining the lowest.ACKNOWLEDGEMENTSThe paper has included results from the DEEPMINE collaborative research programme, this is clearly acknowledged and DEEPMINE management thanked for this permission.The paper however also includes observations from many other independent studies and expresses the authors' opinion and not necessarily that of DEEPMINE management.The paper has also included aspects of the new VUMA software for simulating underground ventilation conditions, this is clearly acknowledged and VUMA management thanked for this permission.REFERENCESHemp R.`Sources of heat in mines'.Chapter 22 in Environmental Engineering in South African Mines, Mine Ventilation Society of South Africa, 1982Von Glehn F.H, Bottomley P, Bluhm S.J.`An improved method of predicting heat loads in face zone of stopes' Proceedings of ASHRAE-FRIGAIR 90 Conference, Pretoria, April 1990Whillier A.`Heat transfer'.Chapter 19 in Environmental Engineering in South African Mines, Mine Ventilation Society of South Africa, 1982.Von Glehn F H, Bluhm S.J.`The flow of heat in an advancing stope' Gold 100, Proceedings of the International Conference on Gold, Vol 1, Johannesburg, SAIMM, 1986Bluhm S.J, Bottomley P, Von Glehn F.H.`Evaluation of heat flow from rock in deep mines' Journal of the Mine Ventilation Society of South Africa, March 1989Von Glehn F.H, `Study of heat exchange in advancing stopes' MSc dissertation, University of Witwatersrand, 1988Starfield, A.M.`Heat flow into the advancing stope' Journal of the Mine Ventilation of South Africa.February 1966Bluhm S.J, et.al.`The measurement of heat loads in a deep level stope in the Klerksdorp goldfield' Journal of the Mine Ventilation Society of South Africa, October 1986Matthews M.K, Mccreadie H.N, March T.C.`The measurement of heat flow in a backfilled stope' Journal of the Mine Ventilation Society of South Africa, November 1987Funnell R.C, et.al.`Examination of cooling effects in stopes using hydropower water' stopes' Proceedings of ASHRAE-FRIGAIR 2000 Conference, Johannesburg, March 2000Vieira F, Diering D, Durrhiem R.`Methods to mine the ultra-deep tabular gold bearing reefs of the Witwatersrand basin, South Africa.Text in preparation for `Techniques in underground mining' Bullock R ed.SME, 20012I SZKOŁA AEROLOGII GÓRNICZEJ 19995408PROCEEDINGS OF THE 7TH INTERNATIONAL MINE VENTILATION CONGRESS407HEAT LOADS AND COOLING REQUIREMENTS FOR DIFFERENT ULTRA-DEEP [ Pobierz całość w formacie PDF ]
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.It was observed that the in-stope heat load generated, per ton mined, would vary considerably for the different layouts.This can be explained in terms of face/gully utilisation, the heat load due to the ventilated face/gully length, the related exposed hot rock and the effect of backfill.The heat loads of dip pillar underhand and overhand scenarios were relatively low while those ascribed to the down dip scenario were generally higher.This stresses the importance of face utilisation and supports the view that higher stope advance rates should improve the effectiveness of ventilation and cooling systems.Detailed lists of criteria were used to judge the merits of the different layouts qualitatively.Weighting factors were set to each criteria and each layout was scored through consensus with deep mine ventilation specialists and practitioners.In terms of this comparison, the dip-pillar down-dip mining layout fared better than the others.The dip-pillar breast layouts fared best in terms of escape and rescue considerations, while the strike-pillar layout offered the best advantages in terms of development and multi-blasts needs.However, the four layouts were grouped fairly closely with 18 percentage points separating the best from the worst.Sensitivity studies on the effect of backfill showed that the stope heat load per unit ton mined increased by 30 percent without backfill [irrespective of the layout examined].However, through water drainage, backfill has the potential to create a heat load if the slurry is allowed to arrive hotter than the desired stope temperature.This effect can be relatively simply reversed by cooling the backfill prior to placing it.New finite-difference models for predicting the transient cooling effects of cold water in stopes are now systematically leading to important observations.One of these is that the cooling optimum approach for stopes in very hot rock will require the supply of relatively cold ventilation [with coolers at stope entrance], the use of high efficiency in-stope air coolers, the use of cold service water and modest quantities of free water [possibly 30 minutes before personnel re-enter].Although this paper is mainly concerned with the micro-level [in-stope] environment and considerations, there are two important observations to note on the macro-level.Firstly, the contribution of in-stope heat to the total mine heat load is less than that of the intake tunnelling [for all layouts considered].This means that, for these ultra-deep mines, the air conditioning energy balances of the stopes are less than that of the intake system.Secondly, the total mine-wide costs of owning and operating the ventilation and cooling systems vary by about 20 percent for the different layouts, with the strike-pillar breast mining the highest and dip-pillar overhand breast mining the lowest.ACKNOWLEDGEMENTSThe paper has included results from the DEEPMINE collaborative research programme, this is clearly acknowledged and DEEPMINE management thanked for this permission.The paper however also includes observations from many other independent studies and expresses the authors' opinion and not necessarily that of DEEPMINE management.The paper has also included aspects of the new VUMA software for simulating underground ventilation conditions, this is clearly acknowledged and VUMA management thanked for this permission.REFERENCESHemp R.`Sources of heat in mines'.Chapter 22 in Environmental Engineering in South African Mines, Mine Ventilation Society of South Africa, 1982Von Glehn F.H, Bottomley P, Bluhm S.J.`An improved method of predicting heat loads in face zone of stopes' Proceedings of ASHRAE-FRIGAIR 90 Conference, Pretoria, April 1990Whillier A.`Heat transfer'.Chapter 19 in Environmental Engineering in South African Mines, Mine Ventilation Society of South Africa, 1982.Von Glehn F H, Bluhm S.J.`The flow of heat in an advancing stope' Gold 100, Proceedings of the International Conference on Gold, Vol 1, Johannesburg, SAIMM, 1986Bluhm S.J, Bottomley P, Von Glehn F.H.`Evaluation of heat flow from rock in deep mines' Journal of the Mine Ventilation Society of South Africa, March 1989Von Glehn F.H, `Study of heat exchange in advancing stopes' MSc dissertation, University of Witwatersrand, 1988Starfield, A.M.`Heat flow into the advancing stope' Journal of the Mine Ventilation of South Africa.February 1966Bluhm S.J, et.al.`The measurement of heat loads in a deep level stope in the Klerksdorp goldfield' Journal of the Mine Ventilation Society of South Africa, October 1986Matthews M.K, Mccreadie H.N, March T.C.`The measurement of heat flow in a backfilled stope' Journal of the Mine Ventilation Society of South Africa, November 1987Funnell R.C, et.al.`Examination of cooling effects in stopes using hydropower water' stopes' Proceedings of ASHRAE-FRIGAIR 2000 Conference, Johannesburg, March 2000Vieira F, Diering D, Durrhiem R.`Methods to mine the ultra-deep tabular gold bearing reefs of the Witwatersrand basin, South Africa.Text in preparation for `Techniques in underground mining' Bullock R ed.SME, 20012I SZKOŁA AEROLOGII GÓRNICZEJ 19995408PROCEEDINGS OF THE 7TH INTERNATIONAL MINE VENTILATION CONGRESS407HEAT LOADS AND COOLING REQUIREMENTS FOR DIFFERENT ULTRA-DEEP [ Pobierz całość w formacie PDF ]