Control of Asbestos Emission - Recommendations, Part 2: Milling of Asbestos Ore

IS 12082 (Part 2): 2006 — Scope Summary

This part of IS 12082 focuses on health, safety, and handling procedures related to asbestos, referencing related standards for comprehensive management.

Key Points on Scope:

• Covers methods for airborne asbestos fibre measurement (IS 11450).
• Includes safety and health requirements for occupational exposure (IS 11451).
• Addresses cleaning, disposal, packaging, transport, and storage of asbestos materials (IS 11767, IS 11768, IS 12079).
• Aims to ensure safe handling and environmental protection in asbestos-related work environments.

Important Related Standards Table:

Summary:

IS 12082 (Part 2) integrates these references to provide a comprehensive framework for asbestos risk management, emphasizing worker safety and environmental controls.

flowchart LR
    A[IS 12082 Part 2 Scope] --> B[Airborne Fibre Measurement (IS 11450)]
    A --> C[Occupational Safety (IS 11451)]
    A --> D[Cleaning Procedures (IS 11767)]
    A --> E[Waste Disposal (IS 11768)]
    A --> F[Packaging & Transport (IS 12079)]

IS 12082 (Part 2): 2006 does not explicitly provide formulas or tables under "Terminology." Instead, it references related standards defining asbestos handling and safety terms.

Key Points on Terminology from IS 12082 (Part 2) Context:

• The standard is part of a series addressing asbestos safety, handling, and exposure.
• Terminology aligns with related IS codes such as:
  • IS 11450:1986 — airborne asbestos fiber concentration measurement.
  • IS 11451:1986 — occupational exposure safety.
  • IS 11769 (Parts 1-3) — guidelines for asbestos product safety.
• Definitions usually cover:
  • Asbestos fiber types
  • Exposure limits
  • Measurement methods
  • Safety practices

Recommended Approach:

• Refer to IS 11450 and IS 11451 for precise definitions of asbestos fiber concentration and occupational exposure terms.
• Use IS 11769 for product-specific terminology.

Summary Table: Related IS Codes for Terminology

If you need specific definitions or formulas related to asbestos fiber measurement or exposure limits, please specify, and I can provide those details.

IS 12082 Part 2 primarily sets objectives rather than specific formulas or tables. Its key objectives are:

• To harmonize testing procedures for concrete admixtures.
• To ensure international coordination by aligning with global standards.
• To reflect local practices in India for practical relevance.

Key Points:

• The standard emphasizes consistency in admixture testing.
• It references international standards to maintain global compatibility.
• It supports quality control and reliability in concrete admixture performance.

Since the clause does not provide formulas or tables, refer to related parts of IS 12082 or IS 9103 for detailed test methods and specifications on admixtures.

Summary:
IS 12082 Part 2 focuses on standardizing testing objectives, ensuring international alignment and local applicability, rather than prescribing formulas or tables.

IS 12082 Part 2 (2006) – Sources and Nature of Dust Generation

Key Dust Generating Points (Clause 4.3)

• Material loading
• Size reduction (crushing, screening)
• Material transfer, bagging, and related operations

Dust Generation Nature (Clause 4.3.2)

• Dust becomes airborne mainly at transfer points:
  • Bins → conveyors
  • Conveyor → conveyor
  • Conveyor → crushers/screens
  • Conveyor → bagging/discharge
• Dust remains suspended, degrading work environment quality.

Dust Control Methods

1. Prevention: Minimize bulk material impact, attrition, and air entrainment.
2. Dry dust collection: Enclose transfer points with dust extraction.
3. Wet dust separation: Use water sprays or sprays with additives.

Specifications for Dust Control (Clause 7.4.2)

• Surround dust-generating operations with a green barrier:
  • Minimum 3 rows of fast-growing trees
  • Dense canopy
  • Minimum width 10 m

Enclosure & Extraction (Clauses 4.3.4, Figures 1-5)

• Transfer points must be completely enclosed.
• Use suction hoods (e.g., bucket elevator feeding points).
• Examples include:
  • Conveyor belt enclosures with flexible skirts and inspection doors.
  • Dust hoods on crushers and screens.
  • Aspirator exhaust ducts on screening units.

Summary Table of Dust Control Approaches

flowchart LR
    A[Material Loading] --> B[Transfer Points]
    B --> C[Size Reduction]
    C --> D[Bagging/Discharge]
    B --> E[Airborne Dust Generation]
    E --> F{Dust Control}
    F --> G[Prevention]
    F --> H[Dry Dust Collection]
    F --> I[Wet Dust Separation]

IS 12082 Part 2: Dust Collection and Filtration Systems – Key Points

Design Principles (Clause 4.3.1)

• Exhaust hood: Captures dust at source; must allow operator movement and material flow.
• Ductwork: Channels contaminated air to dust collectors.
• Air cleaner: Removes dust from air (e.g., bag filters with 99.9% efficiency for 0.4 micron particles).
• Fan: Provides required exhaust flow rate.

Dust Control at Transfer Points (Clause 4.3.2)

• Enclose transfer points (bins, conveyors, crushers).
• Methods:
  • Minimize dust generation by reducing impact and air entrainment.
  • Dry dust collection systems.
  • Wet dust separation (water sprays ± additives).

Filter Cloth Selection (Clause 5.5)

• Air-to-cloth ratio critical for filter efficiency.
• Typical air-to-cloth ratio: 1.2 to 3.5 m³/min/m² (varies by dust type).
• Improper cloth → inefficiency and higher emissions.

Maintenance (Clause 6)

• Maintain ducts under vacuum to prevent leaks.
• Use fluorescent patches to mark leaks; change weekly.
• Repair leaks promptly.

Typical Air-to-Cloth Ratio Table (Example)

Dust Collection System Flow (Mermaid Diagram)

flowchart LR
    A[Dust Source] --> B[Exhaust Hood]
    B --> C[Ductwork]
    C --> D[Air Cleaner (Bag Filter)]
    D --> E[Fan]
    E --> F[Discharge / Water Precipitator]

Summary

• Enclose dust sources and transfer points.
• Use efficient hoods and ductwork.
• Select filter cloth based on air-to-cloth ratio.
• Maintain system integrity to avoid leaks.
• Employ wet/dry dust separation as needed.

This ensures effective dust control, operator safety, and environmental compliance.

General Maintenance of Conveyors, Pipes, and Ducts (IS 12082 Part 2)

Key Points from Clause 6 & 7:

• Leak Detection & Repair:

  • Use powered lights to locate dust leaks.
  • Mark leaks with fluorescent patches; change patch color weekly.
  • Repair leaks promptly.
  • Maintain system under vacuum to ensure only in-leakage (prevents dust escape).

• Enclosure & Dust Control:

  • Screw conveyors must be completely enclosed to prevent leakage/spillage.
  • All transfer points connected to dust extractors.
  • Provide dust exhaust connections at chute feeding points, conveyor junctions, and conveyor exits.
  • Use settling boxes on exhaust connections to reduce velocity and material extraction.

Recommended Maintenance Practices:

Additional Notes:

• Air to Cloth Ratio (Clause 5.5) impacts filter cloth selection affecting dust control efficiency.
• Belt width and speed should be adequate to prevent spillage (Clause 7.3.2).

flowchart LR
    A[Dust-laden Air] --> B[Conveyor Enclosure]
    B --> C{Transfer Point}
    C -->|Dust Exhaust| D[Settling Box]
    D --> E[Dust Extractor]
    C --> F[Screw Conveyor (Enclosed)]
    F --> G[Packaging Point]
    B --> H[Leak Detection (Powered Light)]
    H --> I[Patch Marking & Repair]

This ensures dust containment and effective maintenance per IS 12082 Part 2.

IS 12082 Part 2: Control of Asbestos Exposure in Specific Activities

While IS 12082 Part 2 references several related standards, key points for control of asbestos exposure include:

Key References and Their Focus:

Control Measures Summary:

• Airborne Fibre Concentration Limits: Follow IS 11450 for sampling and analysis.
• Engineering Controls: Use local exhaust ventilation and dust suppression.
• Personal Protective Equipment (PPE): Respirators with HEPA filters, protective clothing.
• Work Practices: Wet methods, enclosed systems, restricted access.
• Waste Handling: Follow IS 11768 for safe disposal.
• Cleaning: Use vacuum cleaners with HEPA filters (IS 11767).

Formula for Airborne Fibre Concentration (from IS 11450):

[ \text{Fibre concentration (fibres/ml)} = \frac{N \times A}{V \times a} ]

Where:

• (N) = Number of fibres counted
• (A) = Effective filter area (mm²)
• (V) = Volume of air sampled (liters)
• (a) = Area counted under microscope (mm²)

flowchart TD
    A[Asbestos Handling Activity] --> B[Engineering Controls]
    A --> C[Work Practices]
    A --> D[PPE]
    A --> E[Monitoring Airborne Fibre (IS 11450)]
    A --> F[Waste Disposal (IS 11768)]
    A --> G[Cleaning (IS 11767)]

Summary: Use referenced IS codes for detailed procedures on measurement, safety, cleaning, and disposal to effectively control asbestos exposure.

IS 12082 Part 2: Dust Monitoring and Control - Key Points

Dust Control Measures (Clause 4.3.2)

• Dust sources: Transfer points (bins to conveyors, conveyors to crushers/screens, final discharge).
• Control approaches:
  • a) Minimize impact, attrition, air entrainment.
  • b) Dry dust collection (enclosures + extraction).
  • c) Dust separation via liquid sprays (water or water + additives).

Design Principles (Clause 4.3.1)

• Exhaust hood: Capture dust at source; design for max efficiency & operator movement.
• Duct work: Channel contaminated air to dust collection.
• Air cleaner: Remove dust particles.
• Fan: Provide exhaust flow.

Specifications

• Transfer points: Fully enclosed, connected to dust extraction.
• Loading points: Use rock boxes to reduce velocity and dust.
• Exhaust fans: Pneumatically convey dust to water precipitators.
• Green barrier: Minimum 3 rows of fast-growing dense canopy trees, min width 10 m around operations (Clause 7.4.2).

Typical Dust Control System Components

flowchart LR
    A[Material Transfer Point] --> B[Exhaust Hood]
    B --> C[Duct Work]
    C --> D[Air Cleaner]
    D --> E[Fan]
    E --> F[Water Precipitator / Filter]

Additional Notes

• High-efficiency filters trap dust down to 0.4 micron.
• Cyclone dust separators with water tanks recommended.
• Combination of green barriers + mechanical systems improves control.

This ensures effective dust capture, reduced air pollution, and safer work environment.

IS 12082 Part 2: Cleaning and Waste Disposal Key Points

• Safety & Health: Follow IS 11451 for worker safety during cleaning and waste handling.

• Waste Disposal:

  • Clause 9.2 mandates disposal per IS 11768.
  • IS 11768 covers methods for disposal of asbestos waste safely to prevent environmental contamination.

• Cleaning with Asbestos Fibres:

  • Use wet cleaning methods to minimize dust.
  • Avoid dry sweeping or compressed air cleaning.
  • Use personal protective equipment (PPE) as per IS 11451.

Important Specifications from IS 11768 (Waste Disposal)

Summary Diagram of Cleaning & Waste Disposal Process

flowchart TD
    A[Cleaning Process] --> B{Use Wet Cleaning?}
    B -- Yes --> C[Minimize Dust]
    B -- No --> D[Avoid Dry Sweeping]
    C --> E[Collect Waste]
    D --> E
    E --> F[Package Waste (Double Bag)]
    F --> G[Dispose as per IS 11768]
    G --> H[Ensure Worker Safety (IS 11451)]

Note: Always refer to the latest editions of IS 11451 and IS 11768 for detailed PPE and disposal procedures.

IS 12082 (Part 2) : 2006 references IS 12079 : 1987 for packaging, transport, and storage of asbestos. Key points from IS 12079 relevant here:

Packaging & Transportation of Asbestos

• Packaging:

  • Use airtight, sealed containers or bags (e.g., double-layered polythene bags).
  • Containers must be clearly labeled with hazard warnings.
  • Packaging should prevent fiber release during handling.

• Transportation:

  • Transport in covered vehicles to avoid dust dispersion.
  • Vehicles must be cleaned after transport.
  • Follow local regulations for hazardous material transport.

• Storage:

  • Store in dry, well-ventilated areas.
  • Keep away from heat sources and direct sunlight.
  • Maintain restricted access to prevent unauthorized handling.

Additional References for Safety & Handling:

Summary Table: Packaging Requirements

flowchart TD
    A[Asbestos Material] --> B[Packaging]
    B --> C{Sealed, Airtight?}
    C -- Yes --> D[Label & Transport]
    C -- No --> E[Repackage]
    D --> F[Covered Vehicle]
    F --> G[Storage: Dry & Ventilated]

This ensures minimal fiber release and safe handling during transport and storage.

IS 12082 Part 2 – Disposal of Tailings: Key Points

• Reference Standard: Tailings disposal must comply with IS 11768 provisions (Clause 11.7).
• Wetting: Tailings shall be wetted at or before the deposit point to reduce dust (Clause 11.4).
• Transportation: Tailings from vibrating screens are transported preferably by screw conveyors outside the plant (Clause 11.6).
• Dust Control: Dust-laden air must be filtered before release; a green barrier (≥10 m wide with ≥3 rows of fast-growing dense canopy trees) should surround processing plants to prevent airborne fiber spread (Clause 9.3).
• Packaging & Transport: Follow IS 12079 for packing asbestos fibers, ensuring impermeable bags and safe transport (Clause 10).

Summary Table for Tailings Disposal

Additional Notes:

• IS 11768 details environmental and safety norms for tailings disposal.
• Wetting reduces airborne fiber risk.
• Green barriers act as bio-filters for dust control.

flowchart LR
    A[Tailings from vibrating screen] --> B[Screw conveyor transport]
    B --> C[Wetting at deposit point]
    C --> D[Disposal as per IS 11768]
    D --> E[Environmental safety ensured]
    F[Processing plant] --> G[Dust extractor]
    G --> H[Filtered air]
    H --> I[Green barrier (≥10m, 3 rows)]

For detailed tailings management, consult IS 11768 directly.

IS 12082 Part 2 refers safety and health requirements related to occupational asbestos exposure primarily to IS 11451:1986. Key points:

Safety & Health Recommendations (per IS 11451)

• Occupational Exposure Limits (OEL): Maintain airborne asbestos fibre concentration below permissible limits (typically 0.1 fibres/cc air averaged over 8 hours).
• Air Monitoring: Use IS 11450 method (membrane filter + light microscopy) for fibre concentration.
• Personal Protective Equipment (PPE): Use respirators and protective clothing.
• Hygiene: Provide washing facilities; prohibit eating/smoking in asbestos areas.
• Training: Workers must be trained on hazards and safe handling.
• Medical Surveillance: Regular health check-ups for early detection.

Related Standards (Table 2 References):

Summary Flow for Safety Compliance:

flowchart TD
    A[Identify Asbestos Work] --> B[Air Monitoring (IS 11450)]
    B --> C{Fibre Conc. < OEL?}
    C -- Yes --> D[Continue Work with PPE]
    C -- No --> E[Implement Controls & PPE]
    E --> F[Medical Surveillance & Training]
    D --> F

Follow IS 11451 fully for detailed safety protocols.