Green Liquor (Spent Pulping Liquor) Handling Design, Loading, and Installation.
Green Liquor is a caustic by-product of the Kraft pulping process, formed when black liquor smelt is dissolved in water. Composed mainly of sodium carbonate (Na₂CO₃) and sodium sulfide (Na₂S), its green color comes from colloidal iron sulfide. This corrosive and hazardous liquid requires careful handling, proper PPE, and secure loading systems to prevent burns, toxic gas exposure, and environmental contamination.
SafeRack provides specialized railcar and tank truck loading solutions, integrating closed-loop loading arms, OSHA-compliant fall protection, spill containment, and pressure relief systems to ensure safe operations in pulp and paper mills.
Key Safety Considerations:
- Fall Protection – Operators require gangways and safety cages for safe access during top-loading.
- PPE Compliance – Chemical-resistant gloves, splash-resistant goggles, and respirators are required
- Spill Containment – Track pans and drainage solutions prevent hazardous leaks.
- Ventilation & Gas Detection – Green Liquor can release toxic sulfur gases, requiring monitoring and airflow control.
Green Liquor
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Green Liquor
Green Liquor Handling & Loading Design
Chemical Properties & Safety
- Appearance: Green, opaque liquid with a strong chemical odor.
- Composition: Sodium carbonate, sodium sulfide, and minor impurities from black liquor processing.
- Uses
- Intermediate step in the recovery process for regenerating White Liquor.
- Removes impurities before causticizing treatment.
- Hazards: Highly corrosive, can cause severe burns, lung damage, and toxic gas exposure when mixed with acids or heated.
Loading & Unloading Procedures
Railcar Loading & Unloading
- Green Liquor is top-loaded via closed-loop systems using 3” stainless steel loading arms or chemical hoses.
- Railcars used: 26,000-gallon DOT-111 insulated or non-insulated tank cars equipped with safety valves.
- Typical railcar dimensions: ~9’ outside diameter, 45’-50’ overall length, 6’x6’ center or offset crash box openings.
Required Equipment:
- Fall Protection Systems – GX Gangways with safety cages prevent falls.
- Spill Containment Solutions – Track pans and containment berms prevent environmental contamination.
- Vapor Recovery & Gas Detection – Closed-loop loading arms minimize toxic vapor exposure.
Tank Truck Loading & Unloading
- Approved DOT trailers: MC 307 or low-pressure chemical ISO containers.
- Unloading Method: Typically bottom unloaded using an extension pipe with two flanged valves.
Required Equipment:
- Pressure Relief Valves – Prevent pressure buildup in trailers.
- Grounding & Bonding Systems – Ensures safe static discharge during loading.
- Corrosion-Resistant Hoses & Pumps – Prevents equipment degradation from the caustic nature of Green Liquor.
Products
Supervised Temporary Holding Cell
The Supervised Temporary Holding Cell provides secure wire partitions, lock options, and customizable configurations for controlled detainee confinement.
Evidence & Security Enclosures
The Evidence and Security Enclosures provide durable wire partitions, secure locks, and custom configurations for protected storage and restricted access.
Wire Mesh Partitions and Walls
The Wire Mesh Partitions provide secure, durable enclosures with custom configurations and multiple door options for industrial storage and access control.
Tool Cribs and Equipment Cages
The Tool Cribs and Equipment Cages provide secure, modular storage with easy installation, custom configurations, and durable wire partitions for industrial use.
Driver Cages and Building Access
Our access cages protect your inventory, as well as visitors, vendors, and other warehouse or building personnel.
Mobile Computer Cabinet w/ Welded Shelf
The Mobile Computer Cabinet features steel construction, a welded shelf, a 3-point lock, adjustable shelves, and casters for secure, mobile industrial storage.
4 Shelf Bin Storage Cabinet
The Heavy-Duty 4 Shelf Bin Storage Cabinet features steel construction, lockable bins, adjustable shelves, and a secure 3-point lock for industrial storage.
All Bin Cabinet
The Heavy-Duty All Bin Storage Cabinet features steel construction, lockable bins, a 3-point lock, and sturdy legs for secure industrial storage.
Top View Computer Cabinet w/ Retractable Keyboard
The Top View Computer Cabinet features 12-gauge steel, a retractable keyboard tray, a 3-point lock, and adjustable shelves for secure industrial storage.
Outdoor Storage Cabinet
The Heavy-Duty Outdoor Storage Cabinet features 12-gauge steel, adjustable shelves, a 3-point lock, and a weather-resistant design for secure industrial storage.
Outdoor Storage Cabinet w/ Angle Frame Base
The Heavy-Duty Outdoor Storage Cabinet features 12-gauge steel, an adjustable shelf, a 3-point lock, and a weather-resistant design for secure industrial storage.
Multi-Compartment Outdoor Cabinet
The Heavy-Duty Outdoor Cabinet features 12-gauge steel, 6 high-capacity drawers, a 3-point lock, and weather-resistant design for secure industrial storage.
Top View Computer Cabinet for Flat Screen
The Top View Computer Cabinet provides steel construction, a retractable keyboard tray, a 3-point lock, a power strip, and a slide-out shelf for secure industrial storage.
Extra Workspace Computer Cabinet
The Extra Workspace Computer Cabinet provides steel construction, a retractable keyboard tray, adjustable shelves, a cooling shelf, and a secure 3-point lock for industrial storage.
Multi-Data Entry Computer Cabinet
The Multi-Data Entry Computer Cabinet features steel construction, a 3-point lock, cooling shelf, adjustable storage, a power strip, and a filtration fan for secure industrial use.
Desktop Computer Cabinet
The Desktop Computer Cabinet features steel construction, a retractable keyboard tray, a 3-point lock, a power strip, and a filtration fan for secure industrial workstations.
Small Desktop Computer Cabinet
The Small Desktop Computer Cabinet features steel construction, a clear window, and a space-saving design for secure workstation storage.
2 Compartment Computer Workstation
The 2 Compartment Industrial Computer Workstation features steel construction, adjustable shelves, a power strip, a filtration fan, and a secure 3-point lock for durable industrial use.
In Plant System
The Industrial In-Plant Computer Cabinet features steel construction, adjustable shelves, a power strip, a filtration fan, and a secure 3-point lock for protected workspaces.
Workstation with Accessories
The Industrial Workstation with Accessories features steel construction, a keyboard tray, adjustable shelves, and a swivel stool for a secure, functional workspace.
3 Shelf Bin Cabinet
The 3 Shelf Bin Cabinet provides steel construction, lockable bins, adjustable shelves, and a secure 3-point lock for industrial storage.
4 Drawer Bin Cabinet
The Heavy-Duty 4 Drawer Bin Cabinet provides steel construction, lockable bins, adjustable shelves, and high-capacity drawers for secure industrial storage.
Bin Storage Cabinet w/ Wardrobe Shelves
The Bin Storage Cabinet with Wardrobe Shelves provides durable steel construction, lockable bins, adjustable shelves, and a secure 3-point lock for industrial storage.
Upright Tool Storage Bin Cabinet
The Upright Tool Storage Bin Cabinet features steel construction, lockable bins, adjustable shelves, a pegboard back, and a 3-point lock for secure industrial storage.
All Secure Full-Width Drawer Cabinet with Bins
The All Secure Full-Width Drawer Bin Cabinet provides durable steel construction, lockable bins, adjustable shelves, and heavy-duty drawers for secure industrial storage.
Extra Wide Bin Cabinet
The Extra Wide Bin Storage Cabinet features durable steel construction, lockable bins, adjustable shelves, and a secure 3-point lock for industrial storage.
King Size Bin & Shelf Storage Cabinet
The King Size Bin Storage Cabinet provides durable steel construction, lockable bins, an adjustable shelf, and a secure 3-point lock for industrial storage.
Countertop Bin Door Storage
The Countertop Bin Door Storage Cabinet provides durable steel construction, lockable bins, adjustable shelves, and a secure 3-point lock for industrial storage.
Long Tool and Bin Storage Cabinet
The Long Tool and Bin Storage Cabinet provides durable steel construction, lockable bins, and open shelving for secure industrial tool and part storage.
Slim Line Bin Storage
The Slim Line Bin Storage Cabinet offers compact, durable storage with 12-gauge steel construction, secure lockable bins, and a 3-point locking system, perfect for space-saving industrial organization.
One Sided 210 Bin Rack
The One-Sided 210 Bin Rack provides compact, organized storage with 210 small bins, ideal for maximizing space in workshops, factories, and parts storage areas.
Mobile Bin Rack
The Heavy-Duty Mobile Bin Rack provides durable steel construction, lockable bins, and mobility for secure industrial storage.
Loading Dock Stairs
Prefabricated IBC, ADA, or OSHA Loading Dock Steps
Signs and Signals
Signs and Signals
Top Loading Arms
Top Loading Arms
MaxRack Elevated Platforms
Powered elevating platform system for accessing railcars and trucks
Filters
Green Liquor Solutions
Best Practices for Green Liquor Handling
- Only trained personnel should handle Green Liquor due to its hazardous nature.
- Use proper PPE – chemical-resistant clothing, splash-resistant goggles, respirators, and gloves.
- Ensure ventilation systems are operational to prevent toxic sulfur gas buildup.
- Corrosion Prevention – Regular inspection of storage tanks, pipes, and loading arms for degradation.
- Emergency Response
- Move exposed personnel to fresh air immediately.
- Remove contaminated clothing and wash skin with soap and water.
- Flush eyes for 15 minutes if exposed.
- If ingested, do not induce vomiting—contact poison control immediately.
- Aspiration into lungs can cause fatal chemical pneumonitis—seek immediate medical attention.
Critical Safety Warnings
⚠ DOT-Regulated – Classified as Hazardous Caustic Alkali Liquid, UN 1719.
⚠ Avoid Contact with Acids – May release hydrogen sulfide and other toxic gases.
⚠ Ensure Proper Ventilation – Exposure to sulfur compounds can cause respiratory distress.
⚠ Use Corrosion-Resistant Equipment – Prevents system failure and environmental contamination.
Below are some of the loading and unloading solutions for illustrative purposes only. Our experts will work with you and your team for a custom solution to suit your needs.
Loading Gangways
A wider access gangway (48″-60″ is preferable) as it helps improve access and egress to and from the vessel. In addition, a wider gangway will reduce the risk of the operator’s PPE getting caught, torn or damaged, and will improve productivity and safety. Powered gangway solutions are also an option, with both hydraulic and pneumatic solutions being commonly used.
Loading Arms
In paper millls, Tall Oil Fatty Acid (TOFA), Black Liquor, White Liquor, and Green Liquor (Spent Pulping Liquor) is typically loaded into railcars or tank trucks via boom-supported stainless steel loading arms or chemical hoses with a flange connection. The arm or hose will have a top inlet with a control valve to ensure that it is self-draining after use and is supported along the length of a mechanical loading arm to improve handling, known as a by-pass arm. You can install one liquid and one vapor arm, or mount both the liquid and vapor hoses on one by-pass arm.
For unloading, typically you would use a rigid stainless steel self-draining loading arm with Buna-N, PTFE or Viton seals. Purge lines can be fitted to the arm, for nitrogen purging. Additional features such as parking latches with proximity sensors can be incorporated into the total system to ensure the arm is correctly stowed when not in use, before any rail movement can occur.
Eye Wash/Drench Showers
Spill containment pans will be provided at the point of loading operations and is an essential piece of equipment in overall site safety and environmental protection
Spill Containment
Spill containment pans will be provided at the point of loading operations and are an essential piece of equipment in overall site safety and environmental protection.
Wheel chocks allow for safe access to and storage of treatment chemicals, while spill containment pans utilized at the point of loading operations serve as essential safety and environmental protection tools.
Grounding
While much of the products being transferred in the pulp and paper manufacturing aren’t combustible, it is an industry best practice to include the grounding of all vessels before starting the (un)loading process.
Ground controllers — ensure true grounding before product flow is permitted
Explosion-proof enclosures — meet or exceed UL, CSA and Ex requirements
Non-sparking tools are also recommended while working around this product
Loading Platform Options
Lighting – General exterior and task lighting to illuminate work and walk areas.
Platform & Canopies – Full platform canopies reduce exposure to the elements and improve the safe and productive loading operation from the operator’s perspective.
Operator Shelter—Depending on your site requirements, consider the requirement of an operator or guard building to keep personnel out of the elements. This can be customized to meet specific site requirements.
Wheel Chocks – SPCC options to allow for safe access and storage of water treatment chemicals.
Safety Gates, Stairs, Ladders, & Platforms
Safety Gates will be installed at the top of stairs and any other openings to ensure operator safety.
SafeRack’s line of industrial safety gates is the most flexible product on the market with the ability to span openings between 16” and 36” and is field adjustable with nothing more than a wrench. We also have guardrails, metal handrails, and full-fledged fall protection solutions with customizable options to fit your needs.
Frequently Asked Questions
Yes, all AeroStep platforms meet or exceed OSHA safety standards, ensuring compliance for aircraft maintenance and ground support operations. Features such as enclosed handrails, slip-resistant surfaces, and adjustable height options enhance worker safety.
Green Liquor 101
Things to know about Green Liquor
Green Liquor is regulated by the U.S. Department of Transportation (DOT) and is classified as a hazardous caustic alkali liquid with the DOT identification number UN 1719.
Spent cooking liquor (black liquor) is mixed with sodium sulphate (salt cake) and then heated to lower its viscosity and then pumped into the recovery furnace. The intense heat in the furnace fuses in inorganic elements of the black liquor to form smelt. The smelt is then harvested from the furnace into a dissolving tank where it is mixed with water to form “green liquor”. Carbon and other impurities in the green liquor are settled out in a clarifier, filtered and sent to a landfill. The clarified green liquor is then subjected to a causticizing treatment with hot lime, Ca(OH)2 to convert sodium carbonate into sodium hydroxide. The resulting sodium hydroxide and sodium sulphide, now called “white liquor” is reused as cooking liquor for the wood chips.
Green liquor can cause severe skin burns, eye and lung damage. As any caustic liquid, exposure to green liquor can cause coagulative necrosis that can lead to extensive tissue damage, as well as, damage to the respiratory system if mists or vapors are inhaled.
Caustic Kraft process liquors, under certain conditions, can produce toxic sulfur gases that include hydrogen sulfide, methyl mercaptan, dimethyl sulfide and dimethyl disulfide. These gases are hazardous and their concentration will vary depending on whether the liquor is a strong or weak liquor. Regardless of the concentration, extreme care should be taken while working around these chemicals.
Only properly trained and equipped personnel should be permitted to (un)load turpentine tank cars and tank trucks. Operators should wear approved PPE equipment including impervious clothing, footwear, gloves, splash resistant goggles and a respirator.
First aid measures for exposure include – removing operators from the source of exposure and into fresh air. Remove contaminated clothing immediately; wash skin thoroughly with soap and water; flush eyes with tepid water for 15 minutes. If ingested do not induce vomiting, but immediately call your local poison control center. Aspiration into the lungs can cause fatal chemical pneumonitis. If ingestion has occurred, assume there is a risk of aspiration into the lungs.
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