Comprehensive Vendor Specification for a Slag Crusher Plant

Introduction

The processing of slag, a by-product of metal smelting and refining processes in industries such as steel, copper, and lead, has evolved from a waste management challenge into a significant economic opportunity. Processed slag finds valuable applications as a raw material in cement production, road construction, aggregate for concrete, and soil stabilization. The heart of this valorization process is the Slag Crusher Plant—a robust, integrated system designed to reduce large, irregular slag chunks into precisely graded, marketable aggregates.

Selecting the right vendor for such a plant is a critical capital investment decision. A poorly specified or under-engineered plant can lead to chronic downtime, excessive wear costs, inconsistent product quality, and ultimately, financial loss. This specification document serves as a comprehensive guide for project engineers, procurement managers, and plant operators to define the technical, operational, and commercial requirements when engaging with potential vendors. The objective is to ensure the procurement of a plant that delivers optimal performance, reliability, and return on investment over its entire lifecycle.

1. Project Scope and General Requirements

The vendor must clearly understand that they are responsible for delivering a complete turnkey solution or a functionally operational system as defined below.

• 1.1. Plant Capacity: The vendor shall specify the plant’s designed throughput capacity in Tons Per Hour (TPH). This must be clearly defined for specific input slag characteristics (e.g., bulk density of 1.6 tons/m³) and desired output product sizes. Capacities should be stated as a guaranteed minimum under normal operating conditions.
• 1.2. Feed Material Characteristics: The vendor’s proposal must be based on a detailed analysis of the source slag.
  • Type: Blast Furnace Slag (BFS), Steel Slag (BOS/ EAF), Non-Ferrous Slag.
  • Input Size: Maximum feed dimension (e.g., 500mm x 800mm lumps).
  • Abrasive Index / Hardness: Measured via Bond Work Index or other standard tests.
  • Moisture Content: As-received moisture percentage.
  • Metal Content: Percentage of free or trapped metallic iron (“tramp metal”) within the slag.
• 1.3. Final Product Specifications: The plant must be capable of producing multiple graded products simultaneously.
  • Product Sizes: e.g., 0-5mm, 5-10mm, 10-20mm, 20-40mm.
  • Product Shape: Cubical output is highly desirable for premium aggregate applications.
  • Contamination Control: The final aggregate must have minimal dust and free metal content as per industry standards (e.g., less than 1% metallic content).
• 1.4. Scope of Supply: The vendor’s scope should be explicitly detailed:
  • Included: Primary feeding unit, all crushing stages (primary, secondary, tertiary), screening units(s), magnetic separators(s), conveyor systems with structure & walkways, electrical control panel with PLC/SCADA integration, dust suppression system or dust extraction system (bag house), cable trays & power cabling between supplied equipment,
  • Excluded (to be clarified): Civil works & foundations; Incoming power supply from client’s substation; Water connection for dust suppression; On-site installation labor & lifting equipment; Operational spares.

2. Technical Specifications of Major Sub-Assemblies

This section forms the core technical requirement for the plant’s mechanical integrity and performance.

• 2.1. Primary Feeding System:

  • Vibrating Grizzly Feeder (VGF): Preferred over an apron feeder for most applications due to its combined feeding and scalping action.
  • Specifications: Heavy-duty construction with reinforced deck plates; Grizzly bars with specified gap (e.g., 50-80mm) to bypass fines; Self-cleaning design; Robust vibrator motors with variable speed control to regulate feed rate; Hopper with wear-resistant liners.

• 2.2. Crushing Circuit:

  • A multi-stage crushing circuit is essential for efficient size reduction and achieving quality product shape.
  • Primary Crusher:
    • Type: Jaw Crusher is standard for its high reduction ratio and ability to handle large, abrasive feed.
    • Specifications: Deep crushing chamber; Heavy-duty jaw plates (18% Mn steel minimum); Eccentric shaft on oversized bearings; Hydraulic adjustment for closed-side setting (CSS) for quick product size changes; Toggle plate designed as a safety shear pin.
  • Secondary Crusher:
    • Type: Cone Crusher is ideal for producing well-shaped aggregates at high tonnages.
    • Specifications: Hydraulic system for clamping, adjustment, and clearing; Automatic setting regulation via PLC; Liner wear monitoring system; Robust mantle and concave in high-chrome or Mn steel.
    • (Alternative: Impact Crusher may be considered if the slag is less abrasive but offers higher fines generation.)
  • Tertiary Crusher:
    • Type: Vertical Shaft Impactor (VSI) is highly recommended for achieving superior cubical shape in the final product fractions.
    • Specifications: Anvil ring or rock-on-rock configuration; Hydraulic lid lifter for easy maintenance; Tungsten tip rotors and wear parts.

• 2.3. Screening System:

  • Vibrating screens are critical for classifying material between crushing stages (scalping) and sizing the final products.
  • Specifications: Multi-deck screens (e.g., 2 or 3 decks); High-G exciters or circular motion vibrators; Wire mesh screens with quick-change tensioning systems; Dust-tight covers and receiving hoppers.

• 2.4.Magnetic Separation System:
  This is non-negotiable for recovering valuable scrap metal from steel slag and protecting downstream crushers from tramp metal damage.

• A combination of suspended permanent magnets over conveyor head pulleys and drum-type magnetic separators is standard practice to ensure maximum metal recovery efficiency (>98%).

• Suspended magnets should be self-cleaning type.

3.Dust Control & Environmental Compliance

Slag crushing is a dust-intensive operation requiring robust mitigation measures.

•   Dust Suppression System: Water spraying system at all major transfer points (feeders,crusher inlets,screens). Must include solenoid valves,filters,and nozzles integrated with PLC control

  OR
  Dust Extraction System: Bag-house filter with induced draft fan connected to all major dust generation points through ducting.Emission levels must comply with local statutory regulations(<50 mg/Nm³).

4.Electrical & Control Systems

Modern plants demand high levels of automationfor efficiencyand safety

PLC/SCADA based control panelwith HMI touchscreenfor operator interface

Key functions include:
Sequential start/stopwith interlocking
Real-time monitoringof motor currents,crusher settings,bearings temperaturesetc
Fault annunciationand alarm history
Production data logging(reporting tonnage per product size)
Auto-adjustmentof crusher settings based on load

Variable Frequency Drives(VFDs)on critical motors(e.g.feeder,crushers)for optimized power consumptionand process control

All motors shallbe of premium efficiency(IE3/IE4 class)suitablefor harsh,dusty environments

5.Structural & Mechanical Fabrication Quality

The entire supporting structurefor conveyors,screens,and crushersmustbe fabricatedfrom heavy-duty structural steel(IS2062/ ASTM A36 equivalent)

All weldingshallbe continuousand performedby certified welderswith NDT testingon critical jointsas required

Walkways,ladders,and guardingshallcomplywith OSHAor equivalent international safety standardsprovidingsafe accessfor operationand maintenance

Corrosion protectionvia sandblasting(SA 2½ grade)and applicationof primerand finish coat suitablefor industrial environments

6.Vendor Qualification & Commercial Requirements

Beyond technical specs,the vendor’s capabilityis paramount

Proven Experience:A minimumof five(5)reference installationsof similar capacityand material processingwithin last three yearsincluding contact detailsfor verification

Technical Documentation:The vendor must supplycomprehensive manualsincluding:
GA drawings,P&ID,P&ID diagrams
Foundation drawings& load data
Parts manualwith OEM codesfor wear parts
Detailed operation& maintenance manual

After-Sales Support:A clear offer detailing:
Commissioning& operator trainingon site
Warranty period(minimum12 months on machinery)
Availabilityof sparesinventory& responsetimefor breakdowns(propose SLA)
Service engineer availability

Financial Proposal:The quote shouldbe broken downinto equipmentcosts,freight,taxes,and any optional extrasA separate price listfor recommended initial sparesis mandatory

Conclusion

Specifyinga Slag Crusher Plant requiresa meticulousbalancebetween process engineeringmechanical robustnesselectrical automationand environmental complianceThis document providesa frameworkto ensurethat vendorsbid ona level playing fieldbasedona clear setof performancerequirementsBy adheringto this detailed specificationthe buyer can confidentlyselecta partnercapableof deliveringa plantthat not only meetsthe immediate productiongoalsbut also operatesreliablyandefficientlyformany yearsturningan industrial by-productinto astreamof sustainableprofit