Recovering raw materials

Canadian oil sand processing plants have been developed by Syncrude and Suncor for extraction and upgrading of tar sand bitumen into fuel. Aboveground surface mining and in-situ methods have been developed to recover raw material. Bitumen recovery from surface mined oil sand requires conditioning in order to free the bitumen from the sand matrix. 

Recycling is the use, reuse or reclamation of wastes after they have been generated. Through recycling and reuse, hazardous wastes are routed into production processes rather than being released to the environment. Reclamation is usually considered to be a part of recycling because it recovers raw material for reuse. The processes used to reclaim useful materials from waste often generate hazardous wastes of their own [16,17,20-23]. 

A reduction in the volume of water needed at the paper machine is almost impossible because paper formation will be disturbed if the consistency of the pulp suspension becomes too high. Currently, the stock suspension (i.e., pulp and additives) in the head box of a paper machine contains 97%-99.9% water. The constraint of maintaining pulp suspension consistency means a reduction in water intake has to be realized by reusing the process water. Due to the different purposes and applications in which water is used, the water quality demands vary considerably. Membrane processes can be chosen to produce a specific water quality and are attractive alternatives to facilitate the reuse of water, either alone or combined with biological processes or other chemical and physical processes. In addition, membrane processes are an efficient way to recover raw materials, e.g., coating pigments, from effluents. 

H) Recovering Raw Materials => Segregation of Streams Separation Technologies... 

Processes were developed in recent years in order to recover raw materials from poly(ethylene terephtalate) (PET) and polycarbonate (PC) by hydrolysis. The main focus was the recovery of terephthalic acid and ethylene glycol besides other products such as benzene, salts of terephthalic acid and oxalic acid. Processes developed for PET are also valid for polyesters such as poly(butylene terephthalate) (PBT) and poly(ethylene 2,6-napthalene dicarboxylate) (PEN). The recovery of bisphenol-A (BPA) from PC requires more sophisticated methods due to the low stability of BPA at high temperatures. Often phenol and isopropenyl phenol are obtained as degradation products of BPA. 

In recent years, the interest in the recycling of polyesters and polycarbonates has increased noticeably. New regulations let to the necessity to reduce the amount of waste and to recover raw materials from plastics. In this view, the hydrolysis of polyesters and PC shows promising results. PET is hydrolysed under different conditions in the range from several minutes to several hours. TPA and EG are recovered in high yields close to 100%. Neutral hydrolysis requires high temperatures and pressures for the recovery of TPA. 

Figure 10.7 shows the basic tradeoff to be considered as additional feed and product materials are recovered from waste streams and recycled. As the fractional recovery increases, the cost of the separation and recycle increases. On the dther hand, the cost of the lost materials decreases. It should be noted that the raw materials cost is a net cost, which means that the cost of lost materials should be adjusted to either... 

Fig. 1. An amplified outline scheme of the making of various wiaes, alternative products, by-products, and associated wastes (23). Ovals = raw materials, sources rectangles = wines hexagon = alternative products (decreasing wine yield) diamond = wastes. To avoid some complexities, eg, all the wine vinegar and all carbonic maceration are indicated as red. This is usual, but not necessarily tme. Similarly, malolactic fermentation is desired in some white wines. FW = finished wine and always involves clarification and stabilization, as in 8, 11, 12, 13, 14, 15, 33, 34, followed by 39, 41, 42. It may or may not include maturation (38) or botde age (40), as indicated for usual styles. Stillage and lees may be treated to recover potassium bitartrate as a by-product. Pomace may also yield red pigment, seed oil, seed tannin, and wine spidts as by-products. Sweet wines are the result of either arresting fermentation at an incomplete stage (by fortification, refrigeration, or other means of yeast inactivation) or addition of juice or concentrate.

Other acetyl chloride preparations include the reaction of acetic acid and chlorinated ethylenes in the presence of ferric chloride [7705-08-0] (29) a combination of ben2yl chloride [100-44-7] and acetic acid at 85% yield (30) conversion of ethyUdene dichloride, in 91% yield (31) and decomposition of ethyl acetate [141-78-6] by the action of phosgene [75-44-5] producing also ethyl chloride [75-00-3] (32). The expense of raw material and capital cost of plant probably make this last route prohibitive. Chlorination of acetic acid to monochloroacetic acid [79-11-8] also generates acetyl chloride as a by-product (33). Because acetyl chloride is cosdy to recover, it is usually recycled to be converted into monochloroacetic acid. A salvage method in which the mixture of HCl and acetyl chloride is scmbbed with H2SO4 to form acetyl sulfate has been patented (33). 

Resources for Potash Fertilizers. Potassium is the seventh most abundant element in the earth s cmst. The raw materials from which postash fertilizer is derived are principally bedded marine evaporite deposits, but other sources include surface and subsurface brines. Both underground and solution mining are used to recover evaporite deposits, and fractional crystallization (qv) is used for the brines. The potassium salts of marine evaporite deposits occur in beds in intervals of haUte [14762-51-7] NaCl, which also contains bedded anhydrite [7778-18-9], CaSO, and clay or shale. The K O content of such deposits varies widely (see Potassium compounds). 

Alternative Processes. Because of the large quantity of phosphate rock reserves available worldwide, recovery of the fluoride values from this raw material source has frequently been studied. Strategies involve recovering the fluoride from wet-process phosphoric acid plants as fluosiUcic acid [16961-83-4] H2SiFg, and then processing this acid to form hydrogen fluoride. 

Nickel and cobalt are recovered by processes that employ both pressure leaching and precipitation steps. The raw materials for these processes can be sulfide concentrates, matte, arsenide concentrates, and precipitated sulfides. Typically, acidic conditions are used for leaching however, ammonia is also effective in leach solutions because of the tendency for soluble cobalt and nickel ammines to form under the leach conditions. 

LPG recovered from natural gas is essentially free of unsaturated hydrocarbons, such as propylene and butylenes (qv). Varying quantities of these olefins may be found in refinery production, and the concentrations are a function of the refinery s process design and operation. Much of the propylene and butylene are removed in the refinery to provide raw materials for plastic and mbber production and to produce high octane gasoline components. 

Condensable Hquids also are recovered from high pressure gas reservoirs by retrograde condensation. In this process, the high pressure fluid from the reservoir produces a Hquid phase on isothermal expansion. As the pressure decreases isotherm ally the quantity of the Hquid phase increases to a maximum and then decreases to disappearance. In the production of natural gas Hquids from these high pressure wells, the well fluids are expanded to produce the optimum amount of Hquid. The Hquid phase then is separated from the gas for further processing. The gas phase is used as a raw material for one of the other recovery processes, as fuel, or is recompressed and returned to the formation. 

Larger environmental issues are associated with the manufacture of wet-process acid and elemental phosphoms, than with the manufacture of technical- or food-grade acids and salts from these raw materials. In the manufacture of both wet acid and phosphoms, the 2 5 recovered may... 

Approximately 98% of the potassium recovered ia primary ore and natural brine refining operations is recovered as potassium chloride. The remaining 2% consists of potassium recovered from a variety of sources. Potassium produced from these sources occurs as potassium sulfate combiaed with magnesium sulfate. Prom a practical point of view, the basic raw material for ak of the potassium compounds discussed ia this article, except potassium tartrate, is potassium chloride. Physical properties of selected potassium compounds are Hsted ia Table 3, solubkities ia Table 4. 

Other Processes. Isopropyl alcohol can be prepared by the Hquid-phase oxidation of propane (118). It is produced iacidentaHy by the reductive condensation of acetone, and is pardy recovered from fermentation (119). Large-scale commercial biological production of isopropyl alcohol from carbohydrate raw materials has also been studied (120—123). 

Modifications and improvements to the basic process have been made to reduce the quantity of waste products (21,22) in the wet chemical process, to recover HF, and to economically process low Ta, high Nb containing raw materials (23). Several alternative extraction media have been reported in the hterature. Most, except for tributylphosphate (TBP) (24) and tri- -octylphosphine oxide (TOPO) (25), have never been used in industry. 

Heating the ammonium beryUium carbonate solution to 95°C causes nearly quantitative precipitation of beryUium basic carbonate [66104-24-3], Be(OH)2 2BeC02. Evolved carbon dioxide and ammonia are recovered for recycle as the strip solution. Continued heating of the beryUium basic carbonate slurry to 165°C Hberates the remaining carbon dioxide and the resulting beryUium hydroxide [13327-32-7] intermediate is recovered by filtration. The hydroxide is the basic raw material for processing into beryUium metal, copper—beryUium and other aUoys, and beryUia [1304-56-9] for ceramic products. Approximately 90% of the beryUium content of bertrandite is recovered by this process. 

Ocean Nodules. A less conventional copper resource consists of deep-sea ferromanganese nodules. These nodules are primarily manganese, but some deposits contain over 1% copper. The nodules occur at many ocean sites, but the most valuable deposits are found in the Pacific Ocean. Although a number of companies are studying methods for recovering values from this source, copper resources from nodules must be considered tentative. World resources are estimated at 0.7 biUion metric tons (8) (see Ocean raw materials). 

Sources of Raw Materials. Coal tar results from the pyrolysis of coal (qv) and is obtained chiefly as a by-product in the manufacture of coke for the steel industry (see Coal, carbonization). Products recovered from the fractional distillation of coal tar have been the traditional organic raw material for the dye industry. Among the most important are ben2ene (qv), toluene (qv), xylene naphthalene (qv), anthracene, acenaphthene, pyrene, pyridine (qv), carba2ole, phenol (qv), and cresol (see also Alkylphenols Anthraquinone Xylenes and ethylbenzenes). 

Removal of Unprocessed Materials This would include raw materials, packaging materials, labels and other such items. The toller can either retain the materials at no cost, purchase the materials from their client (if offered), dispose of the materials for the client, ship all unprocessed material back to an indicated client site, or a combination of these options. Compensation must be agreed upon for any client-owned material that the toller retains. Unused packaging materials, labels and other items bearing the client s identity should be strictly managed. They should either be recovered by the client or destroyed in a manner approved by the client. 

Questions that relate to specific considerations contained in company environmental guidelines apply to licensing and tolling of products (all or m part). They do not apply to suppliers of laboratory quantities of proprietary materials, raw material suppliers, or arrangements made with other companies to recover nonproprietary raw materials (for example, solvents and metal compounds). 

A great deal of industrial pollution comes from manufacturing products from raw materials—(1) iron from ore, (2) lumber from trees, (3) gasoline from crude oil, and (4) stone from quarries. Each of these manufacturing processes produces a product, along with several waste products which we term pollutants. Occasionally, part or all of the polluting material can be recovered and converted into a usable product. 

The raw material has to be washed to remove impurities. Diluted sodium hydroxide allows the removal of phenols and benzonitrile, and diluted sulphuric acid reacts with pyridine bases. The resulting material is distilled to concentrate the unsaturated compounds (raw feedstock for coumarone-indene resin production), and separate and recover interesting non-polymerizable compounds (naphthalene, benzene, toluene, xylenes). Once the unsaturated compounds are distilled, they are treated with small amounts of sulphuric acid to improve their colour activated carbons or clays can be also used. The resulting material is subjected to polymerization. It is important to avoid long storage time of the feedstock because oxidation processes can easily occur, affecting the polymerization reaction and the colour of the coumarone-indene resins. 

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