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Author:
Anna Frank, Equipment Selection Expert
Anna Frank, Equipment Selection Expert
Cement dust stands out from ordinary particulate matter due to its aggressive chemical makeup, heightened abrasiveness, and capacity to damage both health and machinery. Given how particles of this bonding agent tend to stick firmly onto surfaces, achieving effective air purification poses a notable challenge.
Chemical Composition
Cement impurities is classified as a moderately toxic substance, primarily due to its calcium compounds. While it approaches the toxicity level of low-hazard materials at acceptable concentrations, it contains toxic micro-impurities. The specific concentration of these impurities increases with the cement dust particle size.
The cement dust composition is not very homogeneous chemically. It consists of Portland clinker and various mineral additives, which can constitute up to 35% of the total mass. The chemical composition of cement dust varies significantly according to the type of mortar being manufactured.
The cement dust composition is not very homogeneous chemically. It consists of Portland clinker and various mineral additives, which can constitute up to 35% of the total mass. The chemical composition of cement dust varies significantly according to the type of mortar being manufactured.
Cement Powder
The cement dust components include several hazardous impurities with significant health impacts:
- diethylmercury (3.7%): damages the central nervous system and kidneys, impairs vision and hearing, and can cause fetal malformations.
- cadmium oxide (0.89%): has a wide range of harmful effects, from causing hypertension to being carcinogenic.
- copper oxide (1.24%): causes damage to the liver and kidneys and adversely affects metabolism.
- lead and its inorganic compounds (1.51%): affect the central nervous system, gastrointestinal tract, liver, and kidneys, leading to pain in the extremities and circulatory disorders.
- thallium carbonate (1.07%): results in neurological and gastrointestinal disorders and hair loss.
- Furthermore, the concentrations indicated are 1,000 to 10,000 times higher than the maximum permissible levels for atmospheric air.
Physical Properties
In its dry, uncompacted state, cement physically constitutes a particulate matter. The size of cement dust does not exceed 200 µm. The fraction of long-lived particles, characterized by a settling velocity of 0.2 to 6.0 cm/s, can reach 25%. Consequently, any disturbance of the dry material formats a contaminants cloud.
This contaminant is highly aerated. The bulk density of cement dust is relatively low, ranging from 1100 to 1300 kg/m³, and it can remain in a fluidized state for some time after production or transport. This property allows it to flow like a liquid over considerable distances through hoses under low pressure (up to 1 bar) and to easily escape from containers through any breach.
Furthermore, the high permeability cement kiln dust exhibits allow it to penetrate the smallest of leaks, such as silo flange gaps, heavily contaminating production and storage areas. In the event of an accidental spill or container failure, it readily forms extensive solids clouds.
Low-density and fluid-like behavior make conventional filtration less efficient since the dust remains suspended longer than typical heavier particles.
Even minor breaches in containers allow easy leakage, increasing chances of escaping capture zones before reaching filtration units.
This contaminant is highly aerated. The bulk density of cement dust is relatively low, ranging from 1100 to 1300 kg/m³, and it can remain in a fluidized state for some time after production or transport. This property allows it to flow like a liquid over considerable distances through hoses under low pressure (up to 1 bar) and to easily escape from containers through any breach.
Furthermore, the high permeability cement kiln dust exhibits allow it to penetrate the smallest of leaks, such as silo flange gaps, heavily contaminating production and storage areas. In the event of an accidental spill or container failure, it readily forms extensive solids clouds.
Low-density and fluid-like behavior make conventional filtration less efficient since the dust remains suspended longer than typical heavier particles.
Even minor breaches in containers allow easy leakage, increasing chances of escaping capture zones before reaching filtration units.
View the cheat sheet for engineers
Selecting the Best Dust Collector for Cement Dust Management
We’ve created a useful cheat sheet and a comprehensive brochure to guide you through the various filter types, their key features, and applications for cement dust.
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Download the resources and learn how to enhance the efficiency of your cement dust collection system!
To counteract these issues, advanced filter designs must incorporate increased surface area, specialized coatings, or multi-stage separation techniques capable of trapping smaller, lighter particles efficiently.
Special kilns are utilized to fabrication clinker, an intermediate product in cement production. High-temperature gases carrying fine particulates exit these kilns during the firing process. The physical properties of cement kiln dust distinguish it from common impurities—it's finer (down to 0.01 microns), abrasive, and toxic. Mineralogically, it comprises primary raw materials like limestone and calcium hydroxide. Additionally, it frequently includes impurities resulting from incomplete sintering during firing, mainly alkali sulfates and chlorides. Clinker kiln dust can also harbor radioactive substances. The density of cement kiln dust varies depending on its composition. The cement dust shape is characterized by its irregularity, fragmentation, and sharp edges.
Cement kiln dust specifications encompass elevated temperatures, a fine and adhesive texture, high electrical resistance, and the presence of corrosive flue gases. On account of these characteristics, adding solids to slurry could cause thickening within a few hours, settling within structures, and ultimately blocking pipelines. Consequently, it's crucial to cleanse the air from these contaminants.
Special kilns are utilized to fabrication clinker, an intermediate product in cement production. High-temperature gases carrying fine particulates exit these kilns during the firing process. The physical properties of cement kiln dust distinguish it from common impurities—it's finer (down to 0.01 microns), abrasive, and toxic. Mineralogically, it comprises primary raw materials like limestone and calcium hydroxide. Additionally, it frequently includes impurities resulting from incomplete sintering during firing, mainly alkali sulfates and chlorides. Clinker kiln dust can also harbor radioactive substances. The density of cement kiln dust varies depending on its composition. The cement dust shape is characterized by its irregularity, fragmentation, and sharp edges.
Cement kiln dust specifications encompass elevated temperatures, a fine and adhesive texture, high electrical resistance, and the presence of corrosive flue gases. On account of these characteristics, adding solids to slurry could cause thickening within a few hours, settling within structures, and ultimately blocking pipelines. Consequently, it's crucial to cleanse the air from these contaminants.
Flammability and Safety
What Is Combustible Dust and How to Manage It
Is cement dust combustible? Pure cement dust in its isolated form is NOT explosive and NOT combustible, but this requires an important clarification related to real industrial conditions. According to official safety standards, cement, sand, limestone, and gypsum in their pure forms are not classified as combustible materials. They do not contain flammable components and do not support combustion. Cement is a mineral material based on calcium silicates and aluminates, which, upon heating, form stable oxides that cannot burn.
In industrial settings, however, cement almost never exists in a completely pure state. At plants, it is often mixed with other materials such as wood dust, coal dust, residual fuel particles, etc. These are so-called hybrid mixtures—combinations of cement dust with materials that are genuinely combustible. Under determined conditions including particle size, the density of cement dust in the air, humidity, and temperature, it can become explosive.
What is micron of cement dust that is critically dangerous? Approximately 90% of explosions involve particles smaller than 50 microns, with concentrations as low as 50 g/m³.
For precise determination of the hazard level at a given facility, specialized tests are carried out to evaluate critical parameters. These assessments measure factors such as the minimum and maximum explosive thresholds, peak explosion pressures, maximum rates of pressure increase, and the intensity of potential explosions.
Facilities employ various measures to mitigate explosion risks. Among them are installation of extraction systems, filtration units, and precipitating devices, complemented by routine maintenance of equipment. It's advisable to conduct a structured Dust Hazard Analysis periodically, typically once every five years.
Furthermore, consider adopting these additional steps to decrease fire hazards:
In industrial settings, however, cement almost never exists in a completely pure state. At plants, it is often mixed with other materials such as wood dust, coal dust, residual fuel particles, etc. These are so-called hybrid mixtures—combinations of cement dust with materials that are genuinely combustible. Under determined conditions including particle size, the density of cement dust in the air, humidity, and temperature, it can become explosive.
What is micron of cement dust that is critically dangerous? Approximately 90% of explosions involve particles smaller than 50 microns, with concentrations as low as 50 g/m³.
For precise determination of the hazard level at a given facility, specialized tests are carried out to evaluate critical parameters. These assessments measure factors such as the minimum and maximum explosive thresholds, peak explosion pressures, maximum rates of pressure increase, and the intensity of potential explosions.
Facilities employ various measures to mitigate explosion risks. Among them are installation of extraction systems, filtration units, and precipitating devices, complemented by routine maintenance of equipment. It's advisable to conduct a structured Dust Hazard Analysis periodically, typically once every five years.
Furthermore, consider adopting these additional steps to decrease fire hazards:
- Increasing the particle size through coarsening;
- Eliminating potential ignition subject;
- Installing physical barriers like blast walls and deflecting canopies to limit the spread of particles and contain a burst's progression.
Standards and Specifications
Here are four key standards addressing construction dust concentrations in workplaces:
1. Directive 2010/75/EU
This directive regulates industrial pollutants by integrating pollution avoidance and control measures. Its primary goal is to uniformly apply regulations across EU member states, aiming to prevent, reduce, and eliminate environmental contamination from industrial activities affecting water, air, and soil.
2. NFPA 660
Developed by the National Fire Protection Association, this thorough guideline directly confronts the dangers presented by combustible dusts and fine particulates. It introduces rigorous standards aimed at diminishing the likelihood of harmful industrial contaminants explosions and simultaneously enhances workplace safety measures across multiple sectors.
3. NFPA 654
A widely acknowledged fire safety standard issued by the NFPA targets the debarment of solids explosions and fires during industrial processes involving combustible solid materials. By offering clear instructions for creating harmless manufacturing conditions, it minimizes risks associated with handling explosive powders and granules.
4. DIN EN 197-1-2011
This standard sets forth requirements for general-purpose binding agents, covering classification, composition, properties, and testing methodologies. It clearly delineates different types (like Types I, II, III, etc.) and details labeling, packaging, and transportation rules for products.
1. Directive 2010/75/EU
This directive regulates industrial pollutants by integrating pollution avoidance and control measures. Its primary goal is to uniformly apply regulations across EU member states, aiming to prevent, reduce, and eliminate environmental contamination from industrial activities affecting water, air, and soil.
2. NFPA 660
Developed by the National Fire Protection Association, this thorough guideline directly confronts the dangers presented by combustible dusts and fine particulates. It introduces rigorous standards aimed at diminishing the likelihood of harmful industrial contaminants explosions and simultaneously enhances workplace safety measures across multiple sectors.
3. NFPA 654
A widely acknowledged fire safety standard issued by the NFPA targets the debarment of solids explosions and fires during industrial processes involving combustible solid materials. By offering clear instructions for creating harmless manufacturing conditions, it minimizes risks associated with handling explosive powders and granules.
4. DIN EN 197-1-2011
This standard sets forth requirements for general-purpose binding agents, covering classification, composition, properties, and testing methodologies. It clearly delineates different types (like Types I, II, III, etc.) and details labeling, packaging, and transportation rules for products.
Practical Measures in Production
A multi-layered approach is essential for effective control. It involves filtration, ventilation, and employee protection.
Given the physical properties of the suspended matter, bag filters, cartridge dust collectors, and cyclones are predominantly employed for filtration in production. Once collected, the airborne particles can either be reintroduced into the original kiln for refiring, processed separately in another kiln, or utilized externally beyond the existing production site.
The ventilation system uses exhaust ducts designed to prevent particulate matter accumulation and clogging, common issues due to the sticky nature of cement dust.
Employee protection involves the use of certified respiratory equipment and adherence to strict hygiene protocols, including dedicated work clothing, shower facilities, and clean eating areas. Furthermore, regular medical examinations, with a focus on respiratory health, are mandatory.
Given the physical properties of the suspended matter, bag filters, cartridge dust collectors, and cyclones are predominantly employed for filtration in production. Once collected, the airborne particles can either be reintroduced into the original kiln for refiring, processed separately in another kiln, or utilized externally beyond the existing production site.
The ventilation system uses exhaust ducts designed to prevent particulate matter accumulation and clogging, common issues due to the sticky nature of cement dust.
Employee protection involves the use of certified respiratory equipment and adherence to strict hygiene protocols, including dedicated work clothing, shower facilities, and clean eating areas. Furthermore, regular medical examinations, with a focus on respiratory health, are mandatory.
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Vladimir Nikulin
Vladimir Nikulin
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