Device for the utilization of calcium carbonate from mussel shells and from sugar production in paper mills

Abstract

Device (1) for modifying / optimizing paper production by adding CaCO3 (2) as a filler to the starting fibers (5) within the stock center (4).

Description

[0001] Pulp and paper mills are industrial facilities where raw materials such as wood, recycled paper and various plant-based raw materials are processed into a wide range of products such as printing paper, packaging materials and specialty items such as filters or decorative films.

[0002] Global paper and board production reached approximately 420 million tons in 2024. The industry will continue to grow, with demand increasing from 420 million tons in 2024 to an estimated 476 million tons in 2032.

[0003] Pulp and paper mills are different but have interconnected functions within the production chain. A pulp mill specializes in converting raw plants into pulp. Pulp is a soft, fibrous material produced by breaking down plant raw materials into their cellulose components. Pulp is the most important raw material for paper mills.

[0004] In paper mills, raw pulp, often with additives such as fillers, dyes, or sizing agents, is processed into paper rolls suitable for various applications such as printing, packaging, and tissue production. The production process in a paper mill includes forming, pressing, and drying the pulp to achieve the desired paper properties such as strength, brightness, or surface smoothness.

[0005] In summary, the pulp and paper manufacturing process begins with the production of pulp. If a brilliant white paper product is desired, the pulp is bleached. Modern mills typically use environmentally friendly bleaching agents such as oxygen, hydrogen peroxide, or chlorine-free compounds to minimize environmental impact.

[0006] Once the pulp is processed, it enters the papermaking phase. Here, the pulp is mixed with water to form a slurry called furnish. Additives such as calcium carbonate or clay are added to improve properties such as smoothness, strength, or printability.

[0007] Fillers play a crucial role in papermaking at paper mills, improving the quality and performance of the final product while reducing costs. By blending fillers with pulp, paper manufacturers improve properties such as brightness, opacity, smoothness, printability, and bulk. Since fillers are generally less expensive than pulp, they offer a cost-effective solution for achieving the desired paper properties.

[0008] Among the various fillers, calcium carbonate, kaolin (kaolin clay), talc, titanium dioxide, starch, bentonite, and synthetic fillers are the most commonly used. The choice of filler depends on factors such as the paper type (newsprint, writing paper, tissue paper, or specialty paper), the desired properties (e.g., brightness and smoothness), and the cost-quality ratio.

[0009] Calcium carbonate is the most widely used filler because it is affordable, has excellent brightness, opacity, and smoothness, and is compatible with alkaline papermaking processes, which increase the paper's durability and resistance to yellowing. It is highly versatile and suitable for producing a wide range of paper grades, from newsprint to high-quality writing and printing paper.

[0010] The unique combination of cost-effectiveness and functionality has made calcium carbonate (CaCO3) an indispensable filler in modern papermaking, enabling manufacturers to produce high-quality paper that meets a wide range of market requirements.

[0011] An innovative and sustainable alternative to traditional sources of calcium carbonate is the use of mussel shells, a byproduct of the fishing industry. Mussel shells are composed of approximately 95% calcium carbonate, along with traces of magnesium carbonate and organic matter, and are typically considered waste. Importantly, mussels naturally absorb CO2 during their life cycle. When mussel shells are used as raw material for papermaking, the CO2 absorbed by the mussels is stored in the paper. If the paper is incinerated after recycling or use, the released CO2 is considered carbon-neutral, as it comes from the shells' natural absorption process and does not represent new emissions.

[0012] Parallel to the continuous growth of the world population, the demand for shellfish products is increasing, with China, India, Chile, Spain, and Italy leading the market. Worldwide shellfish production reached approximately 2.3 million tons in 2022, with Europe accounting for approximately 600,000 tons. More recent publications report even higher amounts of shellfish waste: "10 million tons of oyster, mussel, scallop, and clam shell waste are produced worldwide; the discarded shells are often thrown into the sea or disposed of in landfills, where they alter soils, waterways, and marine ecosystems" (Appl. Science 2023, 13(1), 623). This immense amount of waste is considered non-compostable, which can cause numerous environmental problems, with additional odor nuisance from the decomposition of the organic matter.

[0013] This amount of waste is generated solely from the amount of mussel shells that would otherwise have to be disposed of for nutritional reasons. However, very large numbers of invasive, toxic mussel shell populations are also known worldwide. Zebra and quagga mussels are particularly noteworthy here. These compete with other known mussel species. Their chemical composition also largely corresponds to the composition of limestone from quarries. Therefore, it makes sense to intelligently utilize these aforementioned nutritional and invasive waste products and thereby avoid the adverse side effects described.

[0014] There is also the possibility of making lime, which is waste from sugar production, available for the paper industry. It is known that sugar production requires very large quantities of limestone to purify the raw juice. Depending on the quality of the raw juice, this amounts to 125 to 250 kg to produce one ton of sugar. This limestone can be obtained either conventionally from quarries or from mussel shells.

[0015] However, such large quantities of saturated limestone are produced that sugar factories often have a limestone disposal problem and attempts are made to make saturated limestone available for soil modification.

[0016] Traditionally, farmers use ground limestone (CaCO3) to reduce soil acidity. This limestone from sugar production is often available to farmers at significantly lower cost than agricultural lime. Often, the farmer only pays the truck toll for this lime waste product.

[0017] However, applying too much waste limestone from sugar production to soils can inhibit the release of other nutrients. Furthermore, the use of calcium also increases pore space in the soil. This is a desirable result until the pore space reaches 50% of the total soil volume. However, if too much calcium is applied through overliming, so much pore space can be created that the soil dries out much more easily than before. Thus, the efficiency of water use, whether from rainfall or irrigation, is lost when soils are overlimed.

[0018] From an economic perspective, limestone is a cost-effective raw material at around €50 per ton, while mussel shells are often available as waste from the fishing industry at little or no cost. This not only offers a cost advantage but also the opportunity to divert waste from landfills. Using mussel shells as a replacement for calcium carbonate can reduce the environmental impact of papermaking, reduce dependence on mining activities, and support the principles of the circular economy. By integrating such innovative materials, as well as waste lime from sugar production, the paper industry can improve sustainability while maintaining the quality and performance of its products.

[0019] Further advantages, details and features of the invention will become apparent from the following description of drawing 1.

[0020] This shows in Fig.Figure 1 shows a simplified representation of paper production with a device (1) for utilizing CaCO3 as a filler in paper production. (2) represents a reservoir consisting of mussel shells. These are first processed in (3), ground to the required size, and then transported to the so-called pulp center (4) as filler. There, they are mixed with the starting fibers (5). Within the pulp center (4), the starting fibers—meaning mechanical pulp, cellulose, and waste paper—are mixed together in the required ratio. The mixing ratio depends on the desired paper quality and the specific production recipe.

[0021] The water-diluted fiber pulp is then distributed via line (6) onto a fine-mesh endless screen (7). The movement of the screen causes initial dewatering, while simultaneously felting the fibers into a homogeneous, sheet-like structure.

[0022] After the press (8), in which the paper structure is compacted by pressure and further dewatered, the residual moisture is removed in the next step using usually steam-heated dryers (9), so that the final base paper has a dry content of approximately 97%. In the final step, the sheet thickness of the paper is optimized in the calender (10). Finally, in (11), the paper is ready for a wide variety of applications.

[0023] Of course, the described examples can be modified and supplemented in many ways without departing from the basic idea of ​​the invention. Thus, the invention also relates to the process for optimizing paper production by admixing waste CaCO3 from mussel shells and / or sugar production.

[0024] It should be noted that calcium carbonate is the most widely used filler because it is affordable, has excellent brightness, opacity, and smoothness, and is compatible with alkaline papermaking processes, which increase the paper's durability and resistance to yellowing. It is highly versatile and suitable for producing a wide range of paper grades, from newsprint to high-quality writing and printing paper.

[0025] The modification / optimization is carried out by using mussel shell limestone and / or saturated limestone from the purification of sugar cane juice from sugar production.

[0026] Of course, other CaCO3-containing waste, such as egg and / or snail shells, can also be used as filler in paper production.

[0027] Ultimately, this invention holds particular potential in its ability to replace traditional additives. Replacing some of the conventional additives with waste products can save material costs and natural raw material sources, and, most importantly, eliminate the need for costly procedures for disposing of the ever-increasing amount of waste by recycling it. List of reference symbols 1 Device for the utilization of mussel shells in paper production 2 reservoir for mussel shells 3 Processing facility for mussel shells 4 Fabric Center 5 output fibers 6 Fiber pulp 7 Endless sieve 8 Pressing device 9 dryers 10 Smoothing unit 11 Paper QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited non-patent literature

[0000] Appl. Science 2023, 13(1), 623

[0012]

Claims

[1] Device (1) for modifying / optimizing paper production by adding CaCO3 (2) as filler to the starting fibers (5) within the pulp center (4). [2] Device according to claim 1, characterized by that the modification / optimization of paper production is achieved by adding CaCO3 as a filler from invasive and non-invasive mussel shells (2). [3] Device according to preceding claims, characterized by that is used to modify / optimise paper production by adding CaCO3 from the sugar raw juice purification of sugar factories.

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