Paper thin markets? A look at PCC in paper

By IM Staff
Published: Wednesday, 03 April 2019

Paper markets may be changing but the minerals used within them are still being used in the same way. Ian Wilson takes a look at precipitated calcium carbonate (PCC) and discuses producer developments in 2019.

Precipitated calcium carbonate, or PCC, is derived from limestone, a fine-grained material that is generally greyish in color due to its organic content.

If the limestone were crushed and fine ground, it would only have a brightness of ~80 ISO (on a scale of 0-100), which is too low for the material to be used as a filler and coating pigment. But greyish limestone is often pure and the organic components will be driven off by the calcining process.

Arcos in Brazil is a major area for lime production, with grey limestone deposits. Vietnam meanwhile produces a whitish limestone, from a deposit owned by TLD Vietnam, in Hai Duong province.

The ideal chemistry of limestone that is suitable for processing into PCC, and corresponding details for the Vietnamese material, are shown in Table 1.

PCC1  

PCC2  

The two raw materials necessary for the production of PCC are quicklime and carbon dioxide. These are purified separately, then the quicklime is mixed with water to produce calcium hydroxide, Ca(OH)2, in either liquid form (milk of lime) or as a solid (hydrated lime).

Cooled and purified CO2-bearing kiln gas is then bubbled through the milk of lime in a reaction vessel known as a carbonator. The gassing process continues until all of the calcium hydroxide has been converted to carbonate. This is monitored by checking the acidity level (pH) or by other chemical measurements.
Chemical reactions in the carbonation process can be summarized as:

  • Calcination of limestone in a kiln to drive off carbon dioxide and to produce lime
  • (CaO)CaCO3 + heat » CaO (lime) + CO2 (calcination)
  • Lime delivered to satellite plant, lime slaked (water added)
  • CaO + H2O » Ca(OH)2 (Hydration or slaking)
  • Carbon dioxide bubbled through in a carbonator to give chemically precipitated carbonate
  • Ca(OH)2 + CO2 » CaCO3 + H2O (carbonation)

After the carbonation process is complete, screening is used to further purify the PCC, because any impurities will be coarser than the PCC particles. Most commercial grades have a minimum purity of around 98%, with magnesium carbonate, silica and unconverted lime as the main contaminants.

In a satellite plant, PCC can then be used in the manufacture of paper. Particle shape and size (crystal engineered PCC) can be determined during the processing.

PCC3  

PCC4  

PCC satellite plants

The three main companies involved in establishing PCC satellite plants at paper mills are Minerals Technologies (MTI), Omya and Imerys.

Okutama Kogyo of Japan, Schaefer Kalk of Germany and others have satellite plants.

Minerals Technologies (MTI) United States-based MTI has two main businesses, Specialty Minerals and Performance Materials, and generated total revenue of $1.32 billion in 2017, according to its annual report for that year.

Specialty Minerals accounted for 44% of MTI’s total sales in 2017, from four product lines: paper PCC, specialty PCC, ground calcium carbonate (GCC) and talc. The paper PCC sector had sales in 2017 of $377.7 million, which was 29% of MTI’s total sales, as shown in Figure 1.

PCC5  
Blast from the past: digitalisation means
paper markets have lagged. 

Paper PCC

MTI created the satellite concept where production facilities are built on site at paper mills. It is the world leader in the production of PCC, with capacity for 4.2 million tonnes per year for paper, from 56 satellite plants (see Table 2).

The company said in its 2017 annual report that it has the capacity to double its global production capacity, with Asia showing the strongest growth. But it did not give a timescale or say whether it actually plans to do so.

The company has signed seven satellite agreements in China since 2012, and has two new satellite agreements in Indonesia. MTI will also continue to advance its PCC technology in India, where it has been able to establish leadership in the market with five satellite PCC plants in the past eight years.

Since it introduced its first PCC plant in China in 2004, it now has nine satellite plants (see Table 3) and more are planned.

MTI is receiving increased interest from papermakers which are conducting trials with its PCC FulFill® high-filler technology, as well as evaluating its NewYield® platform of technologies that it hopes will drive further penetration of PCC.

The FulFill® technology is intended to allow papermakers to increase the amount of PCC in paper, replacing more expensive fiber.

The NewYield® technology platform is said to convert a papermaker’s waste stream into usable pigment. This waste stream is mostly found in China, where environmental regulations prohibit burning the material or sending it to landfill.

NewYield® is intended to provide papermakers with a number of benefits. It should eliminate landfill costs, provide an effective paper filler, and reduce emissions and energy costs.

The prospects for these new technologies in China are bright, and MTI is pursuing more than 20 opportunities in the region for PCC filler and new satellites. It is also engaged in discussions with packaging manufacturers in several locations around the globe for the use of coating products in various applications, including white container board and boxboard packaging.

MTI also has new technologies for brown box packaging.

In the paper industry, MTI’s PCC is used in:

  • Production of coated and uncoated wood-free printing and writing papers, such as office papers
  • Filler in the production of coated and uncoated groundwood (wood-containing) paper such as magazine and catalogue papers; and
  • Coating pigment for both wood-free and groundwood papers.
PCC6  

PCC7  

PCC markets for MTI - paper

MTI estimates that, during 2017, more than 90% of North America’s production of uncoated wood-free paper used alkaline technology.

The uncoated groundwood paper market, including newsprint, represents about 20% of worldwide paper production, and paper mills producing wood-containing paper still generally employ acid papermaking technology.

But the conversion to alkaline technology by these mills has been hampered by the tendency of wood-containing papers to darken in an alkaline environment. For this reason, MTI has developed proprietary application technology for the manufacture of high-quality groundwood paper in an acidic environment using PCC (AT® PCC).

Furthermore, because groundwood or wood-containing paper mills use larger quantities of recycled fiber, there is a trend toward the use of neutral papermaking technology in this segment for which MTI supplies traditional PCC chemistries.

MTI now supplies PCC at six groundwood paper mills around the world, and licenses its technology to a ground calcium carbonate (GCC) producer to help accelerate the conversion from acid to alkaline papermaking.

MTI continues to pursue satellite PCC opportunities in the coated paper markets. The Opacarb product line is designed to create value for papermakers and can be used alone or in combination with other coating pigments such as kaolin.

PCC coating products are produced at eight of MTI’s PCC plants worldwide.

MTI has three merchant plants producing PCC. In Germany, there is a plant at Walsum with capacity for 125,000 tonnes per year of PCC for paper coating. PCC is produced for industrial uses in the UK at Lifford, with capacity for 35,000 tpy, and in the United States at Adams, with capacity for 100,000 tpy, also for industrial uses.

MTI announced in June 2014 that its Paper PCC group was to enter the packaging market through an agreement with Zhengda Paper Group.

The company built a 50,000 tpy satellite PCC plant to produce coating-grade PCC in Zhejiang province, China, for use in coated bleached cartonboard for packaging. This was MTI’s first on-site satellite plant to produce PCC for the coated packaging market, and represented an entry point to a market worth as much as $100 million per year.

The end-market for this type of packaging paper is in such areas as containers for food and beverages, cosmetics, pharmaceuticals, and electronic and luxury products.

Imerys PCC plants for paper are shown in Table 4, with Omya satellite plants listed in Table 5.

PCC8  

PCC9  

Okutama Kogyo

Okutama Kogyo has five PCC plants with total capacity for 288,000 tpy. The majority of this capacity, 276,000 tpy, is in Japan and is used to produce 198,000 tpy of filler grade material, with the remaining 90,000 tpy of pigment grade.

The Fuji satellite plant produces 48,000 tpy of filler and 12,000 tpy of pigment. The Nigata satellite plant produces 54,000 tpy of filler. The Fukuyama merchant plant produces 48,000 tpy of filler and 24,000 tpy of pigment, with the Mizuho merchant plant producing 48,000 tpy of filler and 42,000 tpy of pigment.

There is also a merchant plant in Shanghai, producing 12,000 tpy.

The company sells PCC under the tradename TamaPearl® and produces two groups of products: calcite and aragonite.

PCC10  

PCC11  

Schaefer Kalk

Schaefer Kalk has been producing PCC since 1954, marketed under the trade name Schaefer Precarb.

PCC is produced in different crystal modifications and grain shapes. For each of these precipitation products, the physical parameters are optimized for the application, with regards to particle size and particle size distribution, single particles or agglomeration of primary crystals, and specific surface and pore volume.

The largest of Schaefer’s PCC satellite plants is the Schafer Kalk Finland Oy UPM Kymmene paper mill in Selluntie, Finland. This company was established in 2007, and in 2010 it commissioned a plant for the production of highly concentrated PCC slurries. Current capacity is 155,000 tpy.

Schaefer Kalk also has satellite plants at Wattens in Austria, with capacity for 15,000 tpy; at Olsany in the Czech Republic, with capacity for 15,000 tpy; and at Neidenfels in Germany, with capacity for 15,000 tpy.

At Huangzhou in China, there is a satellite/merchant plant with capacity for 30,000 tpy (20,000 tpy satellite and 10,000 tpy merchant) and merchant plants in Germany at Hahnstätten with 80,000 tpy capacity, and in Malaysia at Kuala Ketil with capacity for 30,000 tpy.

At the Hahnstätten merchant plant, some products for paper are produced such as printing papers, thermosensitive and carbonless auto-copying papers, and paper boards with high brightness and opacity. But the relevant capacities are not known.

Overall, Schaeffer Kalk has satellite capacity estimated at 217,000 tpy and merchant capacity at 120,000 tpy, giving a total of 337,000 tpy.

Global production of PCC in 2017

It is estimated that global production of PCC in 2017 was 17 million tonnes. PCC capacity in China was 8.5 million tonnes, which was 50% of global production. PCC satellite production was 6.8 million tonnes, divided as shown in Table 6 and Figure 3.

MTI accounts for 62% of PCC satellite production for paper, with Omya at 15%, Imerys 10%, Okutama Kogyo 4%, Schaeffer Kalk 3%, and others 6%.