Costing an electrolytic process

In this chapter we will first consider briefly the factors involved in costing an electrolytic process and discuss the various figures of merit. Then, cell components and the principles of celt design will be discussed, together with selected examples of reactor geometries. 

A company deciding whether to build a new chemical plant, will consider the percentage return on investment of vital importance. This is defined by the 

The total product cost is computed for each working year by a consideration of the following items. 

Direct costs. The costs of raw materials, utilities (effluent treatment, water and energy for heating, pumping, etc. as well as electrolysis), labour, maintenance and replacement of components (in electrolyses, particularly electrodes or 

Phnt overhead costs. The costs of insurance, administration, safety, medical services, canteen and recreational facilities for the workforce, quality-control laboratories. 

The capital C invested is the total sum of money required initially to set up the plant and it is estimated from  

Many of the items in (a)—(e) above would be difficult to estimate from first principles and the total product cost is more likely to be computed from an 

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Potassium permanganate can be made from potassium hydroxide and manganese dioxide ore using an electrolytic process, as described in U.S. 5,660,712 (unassigned, but clearly owned by Carus Corp.). Estimate the cost of manufacturing potassium permanganate. 

Hydrogen peroxide was discovered in 1818 and its use in bleaching textiles was first suggested in 1866. However, its high cost limited its use in cotton bleaching until 1935. The problem was partially solved by the process using barium peroxide and phosphoric acid. In 1926 hydrogen peroxide was manufactured by an electrolytic process based on the decomposition of persulphuric acid (H SOj) [15]. 

A recent procedure for the preparation of lead and other alkyls of potential industrial application is an electrolytic process utilizing an aluminum cathode, a lead anode, and an electrolyte of NaF 2Al(C2H5)3. Passage of current leads to a quantitative formation of tetraethyllead at the anode and the deposition of high-purity aluminum on the cathode. It has been suggested that the purified aluminum obtained as a by-product may help meet the cost of electrical current and raw materials (14<5). ... 

The cost of isolating pure product from the electrolysis medium. Process strategies which reduce the number of unit processes in the product isolation stage can be very advantageous to the economics of an electrolytic process,... 

In electrolytic processes, the anode is the positive terminal through which electrons pass from the electrolyte. Anode design and selection of anode materials of constmction have traditionally been the result of an optimisation of anode cost and operating economics, in addition to being dependent on the requirements of the process. Most materials used in metal anode fabrication are characteristically expensive use has, however, been justified by enhanced performance and reduced operating cost. An additional consideration that has had increasing influence on selection of the appropriate anode is concern for the environment (see Electrochemical processing). 

The starting material for all industrial chlorine chemistry is sodium chloride, obtained primarily by evaporation of seawater. The chloride ion is highly stable and must be oxidized electrolytically to produce chlorine gas. This is carried out on an industrial scale using the chlor-alkali process, which is shown schematically in Figure 21-15. The electrochemistry involved in the chlor-alkali process is discussed in Section 19-. As with all electrolytic processes, the energy costs are very high, but the process is economically feasible because it generates three commercially valuable products H2 gas, aqueous NaOH, and CI2 gas. 

The design optimization of an electrolytic cell aims at a high throughput with a low energy consumption at the lowest feasible cost. The throughput of an electrochemical reactor is measured in terms of the space time yield, Yt, defined as the volumetric quantity of the metal produced per unit time per unit volume of the process reactor. This quantity is expressed as ... 

The potential benefits of plasma spraying as an SOFC processing route have generated considerable interest in the process. In the manufacture of tubular SOFCs, APS is already widely used for the deposition of the interconnect layers on tubular cells, and has also been used for the deposition of individual electrode and electrolyte materials, with increasing interest in utilizing APS rather than EVD for electrolyte deposition due to the high cost of the EVD process [48, 51,104],... 

One of the most important electrolytic processes is the extraction of aluminum from an ore called bauxite. This ore is mainly composed of hydrated aluminum oxide, AI2O3 XH2O. (The x in the formula indicates that the number of water molecules per formula unit is variable.) In industry, the scale of production of metals is huge. The electrolytic production of aluminum is over two million tonnes per year in Canada alone. As you know from Faraday s law, the amount of a metal produced by electrolysis is directly proportional to the quantity of electricity used. Therefore, the industrial extraction of aluminum and other metals by electrolysis requires vast quantities of electricity. The availability and cost of electricity greatly influence the location of industrial plants. 

In Japan the need for new technology was answered by the development of an electrolytic route to sebacic acid(33). The Kolbe type electrolytic process developed by Asahi involves dimerization of adipic acid half methyl ester salt to give dimethyl sebacate(34). The dimerization proceeds in 92% yield with 90% selectivity based on the adipate half ester. The main drawbacks of this process are the cost of energy utilized by the electrolytic process and the cost of adipic acid. A Chem Systems report indicates a small advantage for the Asahi electrolytic process with ample room for new technology development(35). 

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