Pulping processes processing options

The isolation of cellulose from wood may employ any one of several process options [13,15, 16]. Chemical wood pulp may be derived by delignification using acidic solutions of sulfur... 

Pulping process Liquor pH at 20°C Base options Appropriate end uses... 

Sulfide emissions may of course be bypassed altogether by a change of the pulping process to avoid the use of sulfide [49]. Both the old soda process and nitric acid pulping suffer from the inferior strength properties of the pulps produced. Use of anthraquinone with basically a soda pulping procedure could put this alternative on a more competitive basis, but has not been adopted [50]. So this is not a practical option. 

Sulfite pulps have properties that are desirable for tissues and top quaHty, fine papers. Because sulfite pulping is not as versatile as kraft pulping, various options have been developed, and the choice of a specific process is dependent on individual mill situations. The unbleached pulp has high (60+) brightness compared to kraft pulp and is easily bleached. However, it is limited to select wood species. The heartwood of pine, Douglas fir, and cedars are not easily pulped. Additionally, pulps produced from hardwood have limited economic value because of low strength. 

Oxypro (2) A family of pulp-bleaching processes developed by Air Products and Chemicals. Piloted in 1995 at Pittsfield, MA. Oxypro 0R is for processing mixed office waste papers it uses molecular oxygen, optionally hydrogen peroxide, sodium hydroxide, and a stabilizer. First commercialized in Scotland in 1994. 

The second option involves the use of a CIO2 scrubber. This is a technique presently used in the paper and pulp industry. In the scrubber, the chlorine dioxide reacts with another chemical, such as a sulphite, DMSO, white spirit or an alkaline hydrogen peroxide solution. The hydrogen peroxide solution is most suited to the process described in this chapter as there are no waste streams. The reaction of chlorine dioxide with the alkaline hydrogen peroxide solution is rapid [10]. The reaction equation is as follows ... 

The book is presented in two parts. Part I covers the problems associated with scrap tires and identifies existing and potential source reduction and utilization methods that may be effective in solving the tire problem. Barriers to increased utilization and options for removing the barriers are identified and evaluated. Part II provides information on the use of whole, scrap tires and tire-derived-fuel (TDF) as combustion fuel, and on the pyrolysis of scrap tires. The use of whole tires and TDF as a primary fuel is discussed for dedicated tire-to-energy facilities. The use of whole tires and TDF as a supplemental fuel is discussed for cement manufacturing plants, electric utilities, pulp and paper mills, and other industrial processes. The focus of Part II is on the impact of burning whole tires and TDF on air emissions. The information in the book is from the following documents ... 

Ca(0H)2 suspension ] and recycling the resultant material to the kiln will suffice for disposal. Despite some known impediments to the process (which was once widely used in the sulfite process of wood pulp manufacture), it may become far less expensive than Option 1. A conceptual design for cost purposes has therefore been undertaken. But, although less expensive than Option 1, Option 2 is still not competitive with a number of alternative technologies. 

Part I of this book discusses markets for scrap tires including major issues of the current problem, market barriers, and options for dealing with the waste tire problem. Part II discusses using tires for fuel and tire pyrolysis. This part focuses on use of scrap tires as a primary fuel for dedicated tire-to-energy facilities and as a supplemental fuel for cement pants, electric utilities, pulp and paper mils, and other industrial processes... 

The tooth pulp can become exposed by a variety of processes, including deep caries, trauma or accidentally during cavity preparation in the dental chair [60]. The consequences can be severe, and include pain, infection and necrosis. When the pulp is exposed, steps need to be taken to manage the situation, and these involve either pulp capping with an appropriate material [60,61] or removal of the pulp followed by sealing of the tooth roots. In the present section of the chapter, we consider briefly materials for the first of these options, pulp capping. 

Natural options exist that might someday replace or supplement the synthetic resins listed previously. Tannins, which are natural phenols, can be modified and reacted with formaldehyde to produce a satisfactory resin. Resins have also been developed by acidifying spent sulfite liquor, generated when wood is pulped for paper. Wet process fibreboards frequently use the lignin inherent in the lignocellulosic as the resin [13]. 

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