INTERVENTION AT SULBRITA QUARRY, MOZAMBIQUE Preliminary Report 1.0 INTRODUCTION: The visit to Sulbrita Quarry on 14 and 15 th August 2006 was an initiative undertaken in terms of Project 7, "Action on silica, silicosis and tuberculosis", a project of the Work and Health in Southern Africa (WAHSA) programme. WAHSA is a twelveyear programme for strategic development in occupational safety and health, and environmental health in the SADC region, launched in Botswana in 2004 and is now at its first of the three four-year phases. It is a Swedish International Development Cooperation Agency (Sida) funded initiative in collaboration with the Swedish National Institute for Working Life (NIWL), the Swedish National Institute of Public Health, (NIPH) Southern Africa Development Community (SADC), South African National Institute of Occupational Health (NIOH), with partner institutions in the region.. The overall objective of the programme is to contribute to poverty reduction by social and economic development in the SADC region through improvements in occupational safety and health. Its general aim is to promote workers' safety and health, and create sustainable systems for occupational safety and health (OSH) and public health promotion. During this first phase the programme will establish a solid and well operating basis for long-term actions on OSH by: Strengthening OSH capacity in the region; Collecting reliable information on OSH to serve as a basis for planning actions to improve OSH in the region; Raising awareness in the region about the value of healthy work; and Improving OSH systems in three key areas, action on silica, silicosis and tuberculosis; pesticides and informal small scale enterprises, Project 7, "Action on silica, silicosis and tuberculosis" is aimed at promoting dust control in quarries in Southern Africa. To achieve this a team composed of South African and local professionals selected by project seven because of specific skills and knowledge will be constituted. The team will have to design, implement and evaluate dust control solutions in three in the region. Each quarry will be in a different (i.e. three countries). The solutions that work will then have to be publicized. In each quarry, the project plan is: 1. Identify the sites (criteria for selection includes local institutional support). 2. Constitute an expert team to do a risk assessment and plan practical solutions. The expert team to include local practitioners and local university departments, and will have to include technical people who can build the solutions on site using local materials, preferably mostly what is already used on site or available in the local town. 3. Negotiate a long-term agreement with the quarry management. 4. Measure dust and quartz levels. 5. Construct solutions. 6. Design a maintenance plan. 7. Identify deficiencies in control solutions and fix them. 8. Identify maintenance difficulties. 9. Re-measure dust and quartz levels, after say a year. 10. Cost solutions and operational costs (e.g. maintenance) 11. Write-up the report. 12. Disseminate widely in the quarry industry. This report covers points 1 and 2 mentioned above for Sulbrita Quarry, a quarry in Mozambique. The visit to this quarry was organised by CERSA and conducted by a team whose composition was made of four professionals from Mozambique and South Africa respectively as follows: Mr Paulo Passela of CEISA and a colleague, Mr Dion Marias and Mr Kobus Dekker of South Africa. The aim of having both teams working together is to build capacity within the country to overlook and monitor the implementation of solutions that will be put in place at the quarry to reduce dust exposure. 2.0 RISK ASSESSMENT OUTCOMES 2.1 Direct Reading Dust Level Assessment Outcomes Several assessments utilising a MIE DataRam Model pDR-100 Airborne Particulates Monitor (also known as a tyndallometer) were conducted at various operations at the quarry. This instrument operates utilising a high sensitivity nephelometric monitor whose light scattering sensing configuration has been optimised for the measurement of the respirable fraction of airborne dust, smoke, fumes and mists. The output is presented in textual as well as graphic format and allows for interpretation of various parameters and situations when linked to visual or operational observation. In interpreting the data, it should be borne in mind that that the information should be considered in context of the operations and activities occurring during the observation period. These results are not definitive from a personal dust exposure perspective, but should rather be evaluated with respect to approximate ambient conditions existing at the assessment position. The following observations and interpretation apply to the assessments conducted at the operations in Mocambique on August 2006. Ambient Air Conditions The following results reflect the general fresh air ambient conditions upwind from the quarry operations. pDR-1000 S/N: 00000 Tag Number: 31 Number of logged points: 11 Start time and date: 10:17:51 15-Aug Elapsed time: 00:05:30 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 0.958 mg/m³ Time at maximum: 10:21:07 Aug 15 Max STEL Concentration: 0.066 mg/m³ Time at max STEL: 10:23:21 Aug 15 Overall Avg Conc: 0.178 mg/m³ The peak reflect the impact of pedestrian traffic approximately 5 metres upwind of the monitor. Atlas Copco ROCF9 Drillrig Cabin These results reflect conditions inside the (air conditioned) cabin of the drill rig. pDR-1000 S/N: 00000 Tag Number: 32 Number of logged points: 21 Start time and date: 10:27:13 15-Aug Elapsed time: 00:10:30 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 3.169 mg/m³ Time at maximum: 10:38:07 Aug 15 Max STEL Concentration: 0.133 mg/m³ Time at max STEL: 10:37:43 Aug 15 Overall Avg Conc: 0.233 mg/m³ The original high peak reflects the effect of the external dust levels on the cabin environment following opening of the door. As soon as the door is closed, the dust level drops to approximately 0.1 mg/m3, demonstrating the effectiveness of the filtration system. Plant Area, Ambient Conditions The following results reflect ambient conditions within the plant area, plant stopped. pDR-1000 S/N: 00000 Tag Number: 33 Number of logged points: 6 Start time and date: 10:57:10 15-Aug Elapsed time: 00:03:00 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 0.681 mg/m³ Time at maximum: 10:59:28 Aug 15 Max STEL Concentration: 0.063 mg/m³ Time at max STEL: 11:00:10 Aug 15 Overall Avg Conc: 0.315 mg/m³ Primary Crusher Attendant The following results reflect conditions at the primary crusher attendant position. Activies varied between clearing the tip, tipping into the tip and crushing as indicated below. pDR-1000 S/N: 00000 Tag Number: 34 Number of logged points: 18 Start time and date: 11:19:08 15-Aug Elapsed time: 00:09:00 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 34.513 mg/m³ Time at maximum: 11:19:13 Aug 15 Max STEL Concentration: 0.935 mg/m³ Time at max STEL: 11:28:08 Aug 15 Overall Avg Conc: 1.540 mg/m³ CRUSHING TIPPING INTO MAIN TIP CRUSHING CLEARING TIP Primary Crusher Discharge The following results and photograph reflect conditions at the crusher discharge position. pDR-1000 S/N: 00000 Tag Number: 35 Number of logged points: 5 Start time and date: 11:31:25 15-Aug Elapsed time: 00:02:30 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 72.116 mg/m³ Time at maximum: 11:32:32 Aug 15 Max STEL Concentration: 6.649 mg/m³ Time at max STEL: 11:33:55 Aug 15 Overall Avg Conc: 39.955 mg/m³ Secondary Crusher Discharge The following results reflect conditions at the secondary crusher discharge position. Due to the nature and level of dust encountered at this position, the assessment was concluded after 30 seconds to prevent potential equipment overload and damage. pDR-1000 S/N: 00000 Tag Number: 36 Number of logged points: 1 Start time and date: 11:34:33 15-Aug Elapsed time: 00:00:30 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 74.767 mg/m³ Time at maximum: 11:35:21 Aug 15 Max STEL Concentration: 0.938 mg/m³ Time at max STEL: 11:35:03 Aug 15 Overall Avg Conc: 29.935 mg/m³ This area reflects a high to very high risk area. Primary Screen Discharge The following data and photograph reflect conditions at the primary screen discharge. pDR-1000 S/N: 00000 Tag Number: 37 Number of logged points: 6 Start time and date: 11:36:03 15-Aug Elapsed time: 00:03:00 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 132.884 mg/m³ Time at maximum: 11:38:11 Aug 15 Max STEL Concentration: 4.136 mg/m³ Time at max STEL: 11:39:03 Aug 15 Overall Avg Conc: 20.690 mg/m³ Once again, the results reflect high risk. Secondary Screen Discharge The following results reflect conditions at the secondary screen discharge. pDR-1000 S/N: 00000 Tag Number: 38 Number of logged points: 5 Start time and date: 11:39:44 15-Aug Elapsed time: 00:02:30 Logging period (sec): 30 Calibration Factor (%): 100 Max Display Concentration: 42.242 mg/m³ Time at maximum: 11:41:15 Aug 15 Max STEL Concentration: 1.584 mg/m³ Time at max STEL: 11:42:14 Aug 15 Overall Avg Conc: 9.009 mg/m³ These conditions reflect significant risk to health and safety. General The plant currently operates without any form of dust suppression. This is clearly reflected in the results. It is management’s intention to fit the screens with water sprays for washing purposes. This will result in significant dust level reductions in these areas. The following photographs reflect dust generation associated with other areas and activities in the plant. Stockpile Area on Plant Start-up Potential Dust Control Solutions Although currently some attention is being paid to dust suppression, several activities are underway by management to address additional identified problems. This includes the consideration of accessing water from the local river to utilise as washing medium in the screening plant. In the event that this system is implemented, dust levels downstream from the screens should be reasonably well resolved. Where possible, water will be recovered and re-circulated through the system. In following the process, the following comments apply: 1 Removal of overburden Overburden at the mine is effectively ripped (softs) whilst hards are drilled, blasted, loaded and tipped in areas that are not intended for mining. This process is temporary and has little effect on the overall production process. No further action proposed. 2 Drilling Dust generation from the drilling operation is under control, provided that the cyclonic separator (on the very new drill) is maintained at the current level of effectiveness. The same applies to the cab air conditioning system. 3 Blasting The blasting activity is short-term with a single dust cloud being generated. This is dissipated by prevailing winds and effective measures to suppress dust during major blasts do not exist. No further action proposed. 4 Loading Loading of the broken ore is performed by mechanical loader. Two issues apply. The first is dust generated during material preparation, scooping and tipping into the haul truck. The second consideration is the loader operator. Initially, the loader was supplied with an enclosed cab and equipped with an air conditioning system. Based on observations during the visit, the cab door was left open during loading operations, which indicates that the air conditioning system is inoperative. This is a common occurrence in quarrying operations and is ascribed to lack of spare parts, filters and ineffective maintenance of these somewhat complex systems. As result of the foregoing, the operator should encourage the wetting down of the ore pile to assist with reducing his exposure. 5 Tipping Tipping into the main crusher tip causes significant dust release in “spikes”. This area will prove problematic as the volume being displaced during tipping together with the relative dryness of the material generates significant short-term exposure. The practicality of partially enclosing the tipping point needs to be investigated. 6 Crushing Crushing occurs in several places, ranging from the primary jaw crusher to secondary and tertiary gyratory crushers. The crusher discharges tend to be dusty to very dusty and will pose a challenge to control. In all probability, enclosure of the discharges together with relatively simple extraction and cyclonic separation would assist (the cyclone design would have to focus on the highest possible practical efficiencies that can be reasonably achieved). 7 Screening The primary and secondary screens currently present significant problems as far as dust loading is concerned. In the event that water cannot be used (whether due to water availability or the potential for clogging the screens), dry control technologies such as enclosure with extraction and separation will once again need to be considered. 8 Transfer Points All of the transfer points in operation were unprotected”. The simplest solution would be to construct enclosures with flexible flaps (e.g. conveyor belting) on the ore leaving positions. 9 Stockpile Interim as well final product stockpiling at this quarry is problematic due to the freefall arrangement which is being used. Enclosed discharge points with vertical discharge pipes (as with a “Dedmar” tube configuration) will assist greatly in dealing with this problem. The temporary stockpile tipping point is, however, equipped in this way and no further action will be implemented there. 10 Hauling Roadway dust levels were observed to be significant on dry portions of the quarry (see photograph below). The mine does, however, utilise water tankers to spray road surfaces. Ideally paving or other forms of roadway consolidation should be used to solve this problem. The cost of these solutions may, however, be prohibitive in the long term. Dust generated by wheeled vehicles Conclusion The quarry is suitable for interventions to develop dust control solutions. These solutions and a work plan will be developed during a workshop in Johannesburg in December 2006.