Pulp and paper

Lime is essential for producing Precipitated Calcium Carbonate (PCC), a synthetic white mineral used to enhance paper quality, while reducing costs. In papermaking, filler and pigment quality directly affect brightness, bulk, opacity, gloss, smoothness, and runnability. Variations in on-site PCC production can disrupt process stability and affect final paper performance. PCC is produced through a controlled reaction between lime, water, and carbon dioxide. Key properties, including particle size, crystal morphology, surface charge and brightness, depend on lime purity, reactivity and consistency, as well as stable operating conditions during production. We supply high‑purity, consistent and reactive lime engineered to optimize the PCC precipitation process and produce homogeneous PCC for filler and coating applications. This directly contributes to improved paper brightness, opacity, runnability, and printability. 

In the Kraft process, production continuity is critical. Fluctuations- caused by causticizing yield, mud filtration rate or lime kiln performance can disrupt the availability of key process chemicals and impact pulp production. Lime is used in the causticizing reaction to convert sodium carbonate (Na₂CO₃) in green liquor into sodium hydroxide (NaOH). Together with sodium sulfide (Na₂S), NaOH is essential for converting wood into high quality Kraft or sulfite pulp. This reaction generates lime mud (calcium carbonate), which is filtered and calcined in a kiln to regenerate quicklime and close the chemical recovery loop. Even under stable operating conditions, part of the lime mud must be purged to prevent impurity buildup. This creates a continuous requirement for make‑up lime, typically 5 to 15% of overall alkali demand. During kiln outages or start‑up phases, that requirement can temporarily increase to 100%. 

We ensure dependable delivery of consistent make‑up lime to:  

• maintain the chemical balance in the recovery loop  
• stabilize the causticizing reaction  
• prevent production losses when the kiln is unavailable 

Modern recycled paper mills must reduce freshwater consumption to meet increasingly stringent environmental regulations. As water circuits close, soluble impurities accumulate – increasing microbial activity and creating more challenging water conditions. These impurities promote microbial growth, causing odors, biofouling, and process instability. They can also increase pulp water hardness, raising the risk of scaling in process equipment. Dosing special, high reactivity milk-of-lime into the stock preparation helps control microbial activity and water hardness. Lime stabilizes pH, improves biocide efficiency, and precipitates soluble water hardness as filler. This reduces scaling, eliminates odor, increases additive performance and helps you maintain stable and controlled recycling operations. 

Oxidative bleaching of mechanical, chemical, or recycled pulp requires precise control of reaction conditions to achieve target brightness without damaging fibers. Excessively aggressive bleaching can degrade fibers, reducing, reducing strength and paper quality, lowering yield and increasing unwanted by-products in the process and  wastewater. Milk of lime and magnesia create a buffered alkaline environment that supports more selective and controlled oxidative bleaching of both mechanical and chemical pulp. They help reduce fiber degradation, limit material losses, and lower emissions compared with caustic soda.