1. Allowable concentration of dust in the air of quartz sand and talcum powder workplace
"GB/T13910-2008 Quartz Sand (Powder) Factory, Dust-proof Powder Factory Dust Technical Regulations" has the prescribed limits on the dust concentration of all dust-producing operations in quartz sand and talc processing enterprises.
Table 1 Allowable concentration of dust in the air of quartz sand and talcum workplace
Second, the dust-proof measures of the crushing and crushing process
(1) All equipment used for crushing, crushing, wheel rolling, etc. shall be provided with closed or semi-closed covers according to the feeding and discharging methods; according to the dust-producing point, separate closed covers, integral closed covers or closed chambers shall be adopted respectively. Open production is not allowed in different closed ways. At the same time, reasonable air circulation is designed to ensure the formation of negative pressure inside the closed cover, and the bag dust removal equipment should be used for purification.
Inner filter bag filter
(2) The airtight device shall comply with the principles of easy operation, disassembly, overhaul, firm structure, light weight, tight combination and safety, and shall not be lost due to vibration or material block impact and equipment maintenance.
(3) The connection between the equipment and the pipeline and between the pipeline and the pipeline should be sealed. When connecting dynamically, a flexible sealing connection should be adopted.
(4) Using wet crushing equipment, a continuous water spray device should be installed above the feed inlet, and the lower discharge opening should be suitable for sealing and exhausting.
(5) Under the conditions allowed by the process, the dust-producing work area should adopt ground sprinkler measures. The materials should be spray- dusted during loading, unloading, transshipment, crushing, screening and other processes .
Third, the drying process dust prevention measures
(1) For drying equipment, ventilation and dust removal measures should be taken. The dust-containing gas discharged from the drying equipment has a higher temperature and a higher humidity, and should be cleaned by a wet dust collector. If a dry dust collector is used, measures against condensation and clogging should be taken.
(2) The discharge opening of the drying equipment shall be provided with a closed cover and exhausted.
Fourth, grinding equipment dust control measures
(1) Raymond mill wind system should be operated in positive pressure mode, and the whole system must be tightly sealed.
(2) Raymond mill dust removal should generally be set up with an independent dust removal system, and the purification equipment should use a high efficiency dust collector. Effective measures to prevent condensation and clogging should be taken for dust removal ducts and dry dust collectors.
(3) For the large cyclone and the existing small cyclone that is used as the residual wind, the lower part of the cyclone must be installed with a closed discharger or a closed silo.
(4) The ultrafine grinding powder conveying system must have a good seal. A bag filter should be used for the collection of powder and the purification of exhaust gas.
5. Dust prevention measures for screening and packaging processes
(1) The plane vibrating screen and hexagonal screen shall adopt a partial airtight cover or an integral closed cover, and exhaust air in the upper part; the exhaust air volume may be determined according to the opening area of ​​the cover, and the wind speed of the cover surface is not less than 1.0 m/s.
(2) The high square screen (suspension sieve) should use the original suction port of the casing reasonably, or use the whole closed chamber and exhaust the air at the upper part.
(3) The upper part of the electromagnetic vibrating screen should be sealed, the main body can be exhausted, and the feeding port and the discharging port should be exhausted.
(4) The packing points of talc powder and dry quartz sand (powder) should generally be provided with a partial airtight cover and exhausted on the upper or rear side.
(5) Quartz sand (powder) produced by wet method generally requires wet sand wet storage. When the water content of quartz sand (powder) is less than 8%, an air hood shall be provided at the packing point.
(6) Dust removal in screening and packaging equipment can generally be carried out. The bulk packaging machine for powders should use a closed chamber with an exhaust.
(7) The vacuum cleaning and vacuuming device should be installed in the screening and packaging workshop.
6. Dust-proof measures for material handling and unloading treatment processes
(1) Belt conveyors for conveying dry quartz sand (powder) and talcum powder should adopt a fully enclosed or upper sealed method and a ventilation and dust removal system.
(2) The transfer point and the end discharge point of the belt conveyor shall be provided with a cleaning device or a water spray cleaning device. In the case of dispersion of the transfer point, it is advisable to use a dust removal unit to control it separately.
(3) Bucket hoist should be strictly sealed, generally only need to exhaust at the bottom. In order to reduce the dust concentration of the exhaust air, the air outlet should not be close to the feed port, and should be avoided on the load side. When the height of the hoist is greater than 10m or the temperature of the material is high, the upper part should also be vented.
(4) The screw conveyor may not have an exhaust hood when it is well sealed; however, when the drop is greater than 1.5 m, dry quartz sand (powder) or talc is transported. A local exhaust system shall be provided at the front of the receiving point, and the exhaust air volume shall be able to eliminate the dust when the material falls.
(5) To eliminate the positive pressure generated when the material falls, reduce the drop, reduce the inclination angle of the pipe or increase the volume of the closed cover.
(6) The plate feeder should be provided with a whole airtight cover and exhausted. When discharging to a belt conveyor or a collar crusher, the receiving point should be provided with a partial airtight cover and exhausted.
(7) The pneumatic conveying device should be reinforced and sealed, and the exhaust gas purification should adopt high-efficiency purification equipment.
7. Dust prevention measures for powder storage process
(1) The intermediate silo (bucket) for storing dry quartz sand (powder) and talcum powder can generally be equipped with a bag type dust removal unit at the top according to the receiving mode, or exhausted at the top, and incorporated into the dust removal system.
(2) Bagged dry quartz sand (powder) and talcum powder should be stored in a dedicated warehouse and should not be stacked in the open air. The house should be cleaned regularly or cleaned with a vacuum cleaner.
(3) The silo should be tight and airtight.
(4) When pneumatic conveying is used to directly feed the silo, measures should be taken to reduce the influence of the periodic instantaneous positive pressure of the gas in the silo on the precipitator.
(5) The sedimentation tank produced by wet quartz sand (powder) should not be set in the open air, and should be cleaned regularly, put into storage immediately, and flushed immediately to prevent secondary pollution.
Eight, ventilation dust removal system and pipeline
(1) The local dust removal system, decentralized dust removal system or centralized dust removal system shall be designed according to the process flow, equipment configuration, plant conditions and dust production points.
(2) The principle of system division should be easy to manage, energy-saving and safe production: the same production process, the dust point of the work at the same time, when the distance is small, it should be combined into a dust removal system; dust with different properties, different humidity, different temperature, It is not advisable to use a ventilation and dust removal system. The system should be used according to the specific conditions.
(3) The grinding equipment and drying equipment should be separately equipped with a dust removal system.
(4) Try to use a primary dust removal system. When the gas dust concentration is high and the single-stage dust collector can not meet the discharge standard requirements, two-stage dust removal or multi-stage dust removal can be used; when the gas contains Mars, large wear particles, or has special temperature and humidity changes, it also needs to be increased. Pre-processing device.
(5) When designing the dust removal system, the system air volume, wind pressure, wind speed of each pipe section and other technical parameters should be reasonably determined.
(6) The dust removal system should adopt centralized automatic control, and the production equipment and dust removal equipment should be linked to improve the management level of the dust removal system to ensure the safe and normal operation of the dust removal system, reduce the idling energy consumption and accident rate of the dust removal system; Speed ​​measures to reduce the energy consumption of the dust removal system.
(7) The arrangement of dust removal equipment should be relatively concentrated, and the convenience of ash discharge, ash transportation and maintenance should be considered.
(8) When the temperature of the dust-containing gas is high and the humidity is high, the wet dust removal system should be insulated or heated.
(9) The discharge point and the transfer point of the belt conveyor shall be provided with a partial airtight cover for exhausting. If the drop is large, a flow isolation device should be provided in the chute.
(10) The design of the dust removal pipeline shall comply with the following requirements:
1 The pressure loss balance calculation should be carried out for each parallel pipeline of the ventilation and dust removal system. The relative difference of pressure loss of each parallel pipeline should not exceed 10%;
2 The dust removal pipe should be short and straight, and the inclined angle of the duct should be no less than 45°;
3 When setting the horizontal pipeline, the closed cleaning hole should be set at the appropriate position to facilitate the removal of dust and prevent the pipeline from being blocked;
4 The dust removal pipeline shall have an economic wind speed that prevents quartz dust from being deposited. The vertical air duct should be 15m/s-18m/s, and the horizontal air duct should be 16m/s-20m/s; the pipeline diameter should be no less than 100mm;
5 A detection hole should be provided at the appropriate part of the dust removal pipe. When there are many suction points, air flow adjustment valves should be installed in each branch pipe section;
6 The exhaust vent of the dust removal system should be 3.0m above the roof. If the exhaust affects adjacent buildings, it should be increased according to the specific conditions;
7 Dust removal pipelines should be inspected and maintained regularly, and the outer surface of the pipeline should be treated with anti-corrosion treatment.
(11) Establish a centralized automatic monitoring room for the dust removal system, and adopt air purification and boosting measures for the monitoring room. The indoor positive pressure is not less than 20Pa.
(12) The power distribution and control facilities of the dust removal system shall have the necessary dustproof performance to ensure the normal operation of the dust removal system.
Nine, exhaust hood
(1) Seal the dust source as much as possible. When it is difficult to seal, install an external exhaust hood and connect the hood as close as possible to the dust source.
(2) The exhaust hood should follow the design principles of appropriate type, correct installation position, moderate air volume, sufficient strength, and convenient maintenance.
(3) The dusting point of the dust-producing equipment should be selected according to the characteristics of the dust source and the operating conditions.
(4) In order to effectively control dust dissipation and avoid excessive suction of powder, the position of the hood, wind speed and air volume should be reasonably determined (see Appendix 2), and the airflow in the hood should be uniform.
(5) The exhaust hood should be easy to operate and overhaul, and durable.
(6) Do not arbitrarily damage or dismantle the installed exhaust hood. If it is damaged, it should be repaired in time.
Ten, dust removal equipment
(1) According to the national or local discharge standards, the dust removal system should handle the air volume, the concentration of dust-containing gas, the nature of dust and gas, and the type of production equipment, and choose a dust collector properly. Usually, the most used bag filter and bag The dust removal unit applies a two-stage dust removal combination of cyclone and bag filter to the high concentration dust-producing point. The dryer can be equipped with a wet dust collector or a bag filter.
Table 3 Quartz sand (powder) dry processing production equipment dust collector selection table
Table 4 Dust collector selection table for talc processing equipment
(2) In the cold area, the wet dust collector should be placed indoors, and in winter, heating should be carried out to prevent freezing.
(3) The dust-discharging port of all kinds of dust collectors shall be equipped with a wind-locking discharge device. The quartz powder, talcum powder or sewage and sludge removed from the dust collector shall be treated in time to prevent secondary pollution.
(4) The precipitator should be installed and used according to its performance and technical requirements, and regularly check the working status of the precipitator to ensure that the main performance of the precipitator (treatment air volume, purification efficiency, equipment resistance, equipment air leakage rate, etc.) meets the design requirements. .
(5) The exhaust air of the dust removal equipment in the workshop should be discharged to the outside with the air duct. When the dust removal equipment in the workshop is discharged indoors, the discharge concentration should meet the sanitary standard.
XI, fan
(1) Select the fan according to the air volume, resistance and working conditions of the fan. Figure 6 Centrifugal fan
(2) The ventilator is usually installed after the precipitator; if it is installed before the precipitator, the dust exhaust centrifugal fan should be used.
(3) The ventilator should take necessary vibration and noise reduction measures to make its running noise meet the corresponding noise standard requirements.
(4) The ventilator should be in a good working condition, check regularly, and find that the fault should be eliminated in time.
12. Ash discharge and ash discharge
(1) All types of ash discharge valves of dust collectors should be well sealed to prevent air leakage.
(2) The dry ash removed from the dust collector should be removed and disposed of in time. It is advisable to adopt measures such as closed transportation, wetting, granulation and molding to avoid secondary dust. If it is to be kept in a gray state, it should be cleaned by a sealed car and disposed of properly.
(3) The large-sized bag filter should be transported by negative pressure pneumatic force or by scraper conveyor and bucket elevator to transport the ash to the ash storage bin, and interlocked with the ash discharge valve under the dust collector.
(4) Under the ash storage bin, a ash discharge valve and a humidifier should be installed to prevent dust from being dusted during ash discharge. An ashless bucket small bag dust collector is arranged on the ash storage bin.
13. Commissioning, operation and maintenance of ventilation and dust removal system
(1) After the installation of the ventilation and dust removal system, the whole system is debugged, and various valves in the system are adjusted to make the system air volume, indenter and wind speed meet the design requirements. The dust at the dust control point does not overflow. The dust removal equipment runs stably and the purification efficiency meets the requirements.
(2) The ventilation and dust removal system should be tested at least once every six months. The inspection items include: treatment air volume, equipment resistance, dust emission concentration, treatment efficiency, air leakage rate, and input power of the motor. Check whether it meets the requirements of the original design. If it does not meet, it should be repaired and adjusted.
(3) The ventilator should always be in a good working condition, the operation should be stable, the shell is not damaged, the impeller is intact, there is no dust and water in the machine, and the motor works normally. The fault should be found out in time.
(4) The level gauge should be set in the dust hopper of the dust collector. The dust accumulation height should not exceed 2/3 of the height of the ash bucket.
(5) The gas storage tank and oil-water separator of the compressed air cleaning system of the precipitator should be discharged once a day.
(6) The outer casing of the precipitator should not be damaged.
(7) Clean up in time according to the dust accumulation of the pipeline.
(8) The strength and tightness of the ventilation dust removal pipeline shall comply with the provisions of GB 50243.
XIV, personal protection
(1) The characteristics of dust generated in the production process of quartz sand (powder) factory and talcum powder factory are different. The content of free SiO2 in the dust of quartz sand (powder) factory is >80%, and the content of free SiO2 in the dust of talc powder factory is <10%. All workers engaged in dust operation in quartz sand (powder) factory and talcum powder factory must select, equip and qualify according to the dust characteristics of the workplace according to the provisions of GB/T 11651 and G8/T18664. Labor protection products.
(2) All workers engaged in dust operations should have the ability to use personal protective equipment correctly, and personal protective equipment should be worn when they are on duty.
(3) Personal protective equipment should be maintained and maintained as required, and replaced regularly as required.
(4) It is strictly forbidden to eat and rest in the dust operation area. The dust working area should have a studio and lounge with air purification and boosting function.
(5) The enterprise shall set up a locker room, a locker box, and a staff bathroom to facilitate the replacement of labor protection articles and showers after work.
(6) Jobs with dust hazard should be marked with “Attention Dust†warning signs and “Dust Dust Mask†instructions and instructions in a prominent position.
15. Management of dust prevention work
(1) A practical maintenance management system should be established according to the number and complexity of ventilation and dust removal system equipment.
(2) Ventilation and dust removal equipment should be managed and assessed in the same way as process equipment, and integrated into the unified management of safety production.
(3) The enterprise shall formulate a technical measure plan for dust control, and improve dust prevention measures so that the dust concentration and exhaust gas concentration in the air of the workplace reach national or local standards.
(4) The necessary rules and regulations should be established, including the responsibility system for dust prevention, the code of duty personnel, operating procedures, operating records, and fault reports.
(5) Implement personnel responsibility system for all levels of dust removal equipment. The ventilation and dust removal system of production equipment shall be operated and operated by the designated personnel, and the technical file of ventilation and dust removal system shall be established.
(6) The enterprise shall conduct regular occupational health examinations before, during and after the post of the dust-collecting workers, and establish the occupational health surveillance files of the laborers, and shall not arrange for personnel who have not undergone pre-job health checkups or have occupational taboos to engage in Dust hazard operations.
(7) Persons exposed to dust who have been diagnosed with occupational diseases must be treated promptly and regularly. Patients with pneumoconiosis must be removed from the dusting operation.
(8) Enterprises should carry out greening around the dust-producing workshop and the warehouse to reduce the pollution of dust to the environment.
16. Education and training for dust prevention work
(1) All types of personnel exposed to dust should be regularly educated and assessed on dust-proof and dust-removing safety production.
(2) Any staff member exposed to dust should be clearly informed of the hazards of the work performed before they are employed.
(3) The operation, maintenance, testing and supervision personnel of the ventilation and dust removal equipment shall receive professional training and may only be employed after obtaining the corresponding qualifications.
17. Inspection and supervision of dust prevention work
(1) The necessary dust test equipment and corresponding test personnel should be equipped.
(2) Quartz sand (powder) factory shall measure the dust concentration in the air of the workshop at least once a week, and increase the air volume, wind pressure, dust removal efficiency and dust emission of each ventilation and dust removal system every month or when adding new equipment and changing the ventilation dust removal system. The amount is measured once. The talc powder factory measures the dust concentration in the air of the workshop and the air volume, resistance and dust removal efficiency of the ventilation and dust removal system at least once every six months. The test results should be compiled and archived. The detection method is performed in accordance with GB/T 5748. If it is found that the dust concentration in the air of the workshop exceeds the limit specified in Table 1, the cause should be found in time and measures should be taken to solve it.
(3) The automatic detection probe of the dust removal system should be regularly maintained and calibrated.
(4) A special person shall supervise and inspect the operation and operation of the ventilation and dust removal equipment, planned maintenance and preparation of spare parts.
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