CPC

The essence of the CPC method consists of recording and interpreting polarisation curves obtained when the polarisable electrode is an electron-conducting ore body (Fig. 2-39). One pole of the current source, electrode A, is connected to the ore body by means of a special device (e.g., in a borehole intersection through the ore body). The 

ZAUj disturbance. To do this a compensation voltage AUc is applied to the measuring potential set. The compensation voltage Ucom is proportional to the current, but has an opposite sign to the voltage ZAU. The compensation voltage is taken from a special resistor (3) in the current circuit (Fig. 2-39). Then at the measuring potential set inlet we 

The current source and current circuit must also satisfy definite requirements (Ryss et al., 1978 Ryss, 1973), including (1) the possibility to change the current over time in different ways up to the maximum values (160-250 A) and (2) minimal resistance in the current circuit (including cable, electrode A, electrode B and all other parts). For 

The CPC polarisation curves of sulphide ore bodies, Kola peninsula, Russia (A) copper-nickel ores (B) pyrrhotite mineralisation. 

The best CPC results are obtained on ore bodies with favourable texture (massive, veined, banded, laminated, etc.), when the ore body as a whole is an electronic conductor. For such ore bodies CPC is able to  

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Figure 16.86 shows the cold-end design with the CP table. Below the pinch, adjacent to the pinch, CP a CPc- Again, the duty on units has been maximized according to the tick-oflF heuristic. 

As each match is successively placed in the interval, the minimum number of matches can be achieved because there is one fewer stream to match and the CP ratio of the remaining streams (i.e., ratio of 2 CPh and 2 CPc of the remaining streams) in the interval still satifies the CP ratio between the composite curves. 

A surfactant solution is a mixture of DTAC (dodecyltrimethylammonium chloride) and CPC (cetyl pyridinium chloride) the respective CMCs of the pure surfactants are 2 X lO M and 9 x IO M (Ref. 140). Make a plot of the CMC for mixtures of these surfactants versus the mole fraction of DTAC. 

This localization phenomenon has also been shown to be important in a case of catalysis by premicellar aggregates. In such a case [ ] premicellar aggregates of cetylpyridinium chloride (CPC) were shown to enhance tire rate of tire Fe(III) catalysed oxidation of sulphanilic acid by potassium periodate in tire presence of 1,10-phenantliroline as activator. This chemistry provides a lowering of tire detection limit for Fe(III) by seven orders of magnitude. It must also be appreciated, however, tliat such premicellar aggregates of CPC actually constitute mixed micelles of CPC and 1,10-phenantliroline tliat are smaller tlian conventional CPC micelles. 

North American HF production capacity has declined since the early 1980s and several smaller producers, such as Harshaw and Essex, have closed plants. Production is expected to continue to decline in the short term because of chlorofluorocarbon (CPC) cutbacks, but is expected to rebound later in the 1990s as replacement hydrochlorofluorocarbons are introduced to the marketplace. 

At least in the short term, European production is expected to be impacted by two trends the move away from planned economics in the East should lead to more rapid demand growth and the phaseout of CPCs, including, in Europe, aerosols (qv), should lead to overcapacity in the West. This excess capacity in western Europe could be used to supply the East. 

Heterogeneous vapor-phase fluorination of a chlorocarbon or chlorohydrocarbon with HP over a supported metal catalyst is an alternative to the hquid phase process. Salts of chromium, nickel, cobalt or iron on an A1P. support are considered viable catalysts in pellet or fluidized powder form. This process can be used to manufacture CPC-11 and CPC-12, but is hampered by the formation of over-fluorinated by-products with Httle to no commercial value. The most effective appHcation for vapor-phase fluorination is where all the halogens are to be replaced by fluorine, as in manufacture of 3,3,3-trifluoropropene [677-21 ] (14) for use in polyfluorosiHcones. 

In Western Europe, the CPC producers are equally varied. The following is a partial Hst of the larger companies with total CPC production capacity (10 t) at all sites shown in parentheses Atochem SA (148.5, Prance and Spain), Hoescht AG (102.0, Germany), KaH-Chemie AG (66.0, Germany and Spain), Montefluos SpA (100.0, Italy), and ICI Chemicals and Polymers Ltd. (>113.6, United Kingdom). These producers account for over 80% of the Western European CPC production. 

In Japan, the primary suppHers are Asahi Glass Co., Ltd. (60,000 t), Daikin Industries, Ltd. (115,000 t), and Du Pont-Mitsui Pluorochemicals Co. (64,000 t). Together these three producers account for over 90% of the Japanese CPC production. 

Confirmation of the destmetion of ozone by chlorine and bromine from halofluorocarbons has led to international efforts to reduce emissions of ozone-destroying CPCs and Halons into the atmosphere. The 1987 Montreal Protocol on Substances That Deplete the Ozone Layer (150) (and its 1990 and 1992 revisions) calls for an end to the production of Halons in 1994 and CPCs, carbon tetrachloride, and methylchloroform byjanuary 1, 1996. In 1993, worldwide production of CPCs was reduced to 50% of 1986 levels of 1.13 x 10 and decreases in growth rates of CPC-11 and CPC-12 have been observed (151). 

The coarse, nonpigmentary cmdes are particle si2e reduced by a variety of processes to obtain pigmentary CPC. Since CPCs are utili2ed in a variety of industries and a host of appHcations, the specific property requirements vary widely. A large number of special-purpose types are commercially available designed to provide optimal properties for specific appHcations. 

Copper Phthalocyanine Green. CPC green is obtained by electrophilic substitution of CPC blue with chlorine, the degree of chlorination reaching 14—15 chlorines per molecule. The typical polychloro-CPCs are blue-shade green pigments. To provide yellower shades of green, substitution of... 

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