Hydrated Lime for Paper Mills & Pulp Industry in India
IS 712 certified Ca(OH)₂ for the Kraft pulping lime cycle — trusted by paper mills across India for consistent causticisation, white liquor quality, and pulping efficiency.
The Role of Hydrated Lime in the Kraft Pulping Process
Hydrated lime (calcium hydroxide, Ca(OH)₂) plays a critical role in the Kraft pulping process — the dominant chemical pulping method used in paper mills across India. In the Kraft process, wood chips are cooked in white liquor (sodium hydroxide + sodium sulphide) to dissolve lignin and release cellulose fibres for papermaking.
After cooking, the spent white liquor (now called black liquor) is recovered, concentrated, and burned in a recovery boiler to produce green liquor (sodium carbonate + sodium sulphide). Hydrated lime is then used in the causticisation process to convert the green liquor back to white liquor — completing the chemical recovery cycle that makes Kraft pulping economically viable.
Paper Mill Applications of Hydrated Lime
Causticisation — Green Liquor to White Liquor
In the causticisation process, hydrated lime reacts with sodium carbonate (Na₂CO₃) in green liquor to produce sodium hydroxide (NaOH) — the active cooking chemical in white liquor. The reaction is: Ca(OH)₂ + Na₂CO₃ → 2NaOH + CaCO₃. The calcium carbonate (lime mud) is separated, washed, and sent to the lime kiln for regeneration. The quality of the hydrated lime determines the efficiency of causticisation and the strength of the white liquor.
Industrial Grade (80–85%) or Premium Grade (88–92%)
Lime Mud Reburning
The calcium carbonate (lime mud) produced in causticisation is reburned in a rotary lime kiln to regenerate quick lime (CaO), which is then slaked to produce hydrated lime for the next causticisation cycle. This closed lime cycle reduces lime consumption and operating costs. The quality of the reburned lime depends on the kiln temperature, residence time, and the purity of the lime mud.
Quick Lime (85–90% CaO) — for slaking to produce hydrated lime
Effluent Treatment
Paper mills generate large volumes of high-BOD, high-COD effluent from pulping, bleaching, and paper machine operations. Hydrated lime is used in the effluent treatment plant (ETP) for pH correction, coagulation, and heavy metal precipitation to meet CPCB discharge standards.
Industrial Grade (80–85%)
Bleaching Process pH Control
In the bleaching sequence, pH control between stages is critical for bleaching efficiency and fibre quality. Hydrated lime is used to adjust pH in alkaline extraction stages (E stages) of the bleaching sequence.
Industrial Grade (80–85%) or Premium Grade (88–92%)
Precipitated Calcium Carbonate (PCC) Production
Some integrated paper mills produce precipitated calcium carbonate (PCC) on-site for use as a paper filler and coating pigment. PCC is produced by reacting quick lime with water (slaking) and then carbonating the lime milk with CO₂. High-purity quick lime is essential for producing bright, fine-particle PCC.
High Purity Quick Lime (88–92% CaO)
Recommended Grades for Paper & Pulp Mills
Application
Recommended Grade
Why
Causticisation (green liquor treatment)
Industrial (80–85%) or Premium (88–92%)
Higher Ca(OH)₂ = better causticisation efficiency
ETP pH correction
Industrial (80–85%)
Cost-effective for large-volume treatment
Bleaching pH control
Industrial (80–85%) or Premium (88–92%)
Consistent dosing for pH maintenance
PCC production (quick lime)
High Purity CaO (88–92%)
High purity for bright, fine PCC
Why Paper Mills Choose Shree Ram Lime
Consistent Purity for Causticisation
Causticisation efficiency depends directly on Ca(OH)₂ content. Our in-house laboratory tests every batch. Consistent purity means consistent white liquor strength and stable pulping operations.
IS 712 Certified
IS 712 test certificates with every shipment. Supports your raw material quality documentation and ISO 14001 environmental management requirements.
Low Moisture Content
Moisture controlled below 2% (IS 712). Dry lime ensures accurate weighing in automated lime dosing systems and prevents clumping in storage silos.
Reliable Continuous Supply
Paper mills operate 24/7 and cannot afford supply interruptions. We maintain production capacity and inventory for monthly contracts with consistent delivery schedules.
Both Hydrated Lime & Quick Lime
We supply both hydrated lime (for causticisation and ETP) and quick lime (for PCC production and on-site slaking systems) — a single supplier for all your lime requirements.
Pan-India Delivery
From Pipar City, Jodhpur, we supply to paper mills across Rajasthan, Gujarat, Maharashtra, Andhra Pradesh, Tamil Nadu, and other paper-producing states.
