Pulp Making by Soda-Anthracite Process
Introduction
Pulp and paper making needs a lengthy process of pulping and bleaching in order to produce quality paper products. In the past, sulfite processes were used in the production of pulp due to a number of advantages, such as good bleaching capability and lower costs. But, over the years, the need for high brightness and color, plus the unfavorable environmental effects, made the process less popular among the industry.
Soda-anthracite process is one of the newer methods used for pulp manufacturing in Europe and the United States, and it is gaining popularity every day due to its low cooking costs and its capability to produce a high brightness pulp from bamboo and other renewable sources. In this paper, we will discuss, in detail, the soda-anthracite process, and its advantages, disadvantages and environmental effects of using this process.
Description of Process
The soda-anthracite process is a chemical pulping method that utilizes the properties of sodium hydroxide (NaOH) and carbon to create pulp. In this process, chips or logs of raw materials are first cut into small pieces. These pieces are then heated in a digester with a combination of sodium hydroxide, carbon and steam. This mix creates an alkaline and high pressure reaction that chemically cooks the wood chips in the digester.
The combination of the alkaline solutions, pressure, and temperature causes the chemical bonds (lignin) to become less rigid. This softens the wood chips fibers, making it easier to separate the fibers from one another. The fibers become more pliable due to the release of lignin, cellulose and hemicelluloses from within the wood chips. After this, the remaining lignin is removed from the pulp with an anthracite solution.
The anthracite solution removes the lignin by oxidizing it before being separated from the pulp. This process creates a light color pulp that is known for its high brightness. After this, the pulp is bleached to make it whiter and then the pulp can be processed further depending on the desired outcome.
Advantages
The soda-anthracite process is considered advantageous when compared to some of the older pulping methods due to a number of factors, outlined below:
1. The process has a higher yield, meaning that more pulp can be produced from a given amount of raw materials.
2. It produces high brightness pulp products, allowing for higher quality paper products.
3. The process is less expensive than some other pulping processes, making it an attractive option for manufacturers.
4. The process does not produce a large number of hazardous chemicals, which makes it a safer and more environmentally friendly option than some other processes.
Disadvantages
The soda-anthracite process does have some drawbacks, detailed below:
1. The process is not always capable of producing a very high brightness pulp.
2. The process uses sodium hydroxide, which is a hazardous chemical, thus imposing safety requirements and adding extra expense.
3. The process generates large quantities of sludge as a byproduct, which can be difficult and expensive to dispose of in an environmentally friendly manner.
4. The process is energy intensive, making it more costly than some other methods.
Environmental Effects
The soda-anthracite process has some environmental effects that must be considered when determining whether or not the process is suitable for a particular situation. The most important of these effects are discussed below:
1. The process releases a large amount of sludge, which can contain hazardous chemicals and may be hazardous to local wildlife.
2. The process produces methane gas as a byproduct, which can be damaging to the environment if not managed properly.
3. The process requires large amounts of energy and water, which can be damaging to local ecosystems.
Summary
The soda-anthracite process is a relatively new method of pulping which is gaining popularity due to its low cooking costs, high brightness production and potential to produce a pulp from renewable sources such as bamboo. The process has several advantages, including a higher yield, cost effectiveness, and the ability to produce high-quality pulp with fewer hazardous chemicals. On the downside, the process is not always capable of producing the desired brightness levels; it uses a hazardous chemical, produces large quantities of sludge and wastes large amounts of energy and water. Lastly, the process has several environmental impacts that must be considered when deciding if the process is suitable for a given situation.
