Copper cementation

Cement clinker Cement-composites Cement copper Cemented carbide... 

There is virtually no knowledge of the setting and stmcture of copper phosphate cements. Mostly, they are complex materials. The simplest was based on a powder containing 91-5% CuO and 8-4% CO3O4. Others contained respectively 62-2 % CuO and 29-8 % ZnO, and 23-9 % Cu O and 66 7% ZnO, with other metal oxides. The strength of these cements is about the same as the zinc phosphate cement (Ware, 1971). There are also pseudo-copper cements, which are zinc phosphate cements coloured by minor amounts of copper(II) oxide. 

Scrap iron - [PIGMENTS - INORGANIC] (Vol 19) -for copper cementation [COPPER] (Vol 7)... 

The copper cementation reaction consists of two half-cell reactions one oxidizing (loses electrons) and the other reducing (gains electrons) ... 

T. N. Lung, The History of Copper Cementation on Iron—the World s First Hydrometallurgical Process from Medieval China, Hydrometallurgy, YI, 113-129 (1986). 

Formation of the mixed cement-containing systems within the range of low copper concentrations with addition of alkali metal dopants as well as catalytical properties of these systems in the ethane oxidative chlorination process have been investigated. Based on the obtained data the efficient and stable copper-cement catalyst has been worked out. This catalyst will assist in the development of a new technology of the vinyl chloride production from ethane. The basic peirameters of the ethane oxychlorination process have been determined at 623-673K, time-on-stream 3-5s and reactant ratio of C2H6 HCI 02 = 1 2 1 the conversion of ethane is more than 90% and the total selectivity to ethylene and vinyl chloride is 85-90%. 

Thus, the activity of copper—cement catalysts in Deacon reaction is comparable with that of commonly used salt catalysts. 

Thus, cement-containing systems provide the conversion of dichloroethane to be increased to more than 70% even at 673K. An important positive factor is that vinyl chloride molecule is stable at this temperature. At 673K, the side reaction of vinyl chloride dehydrochlorination with forming acetylene proceeds slowly, acetylene does not form, and the reaction is not complicated by the formation of a number of by-products, for example, of perchloroethylene. Thus, the above-made supposition about bifunctional character of copper—cement catalytic systems was confirmed in the investigations of their activity in the above-mentioned reactions. 

The results obtained substantiate that the utilization of copper—cement catalysts offers promise for the synthesis of vinyl chloride from ethane at law temperatures in a single step. The proposed efficient and stable copper-cement catalyst will assist in the development of a new technology for the production of vinyl chloride Ifom ethane. This technology is low-waste and balanced in raw materials with meeting modem requirements of ecological safety. 

Modifications are in progress for the treatment of the cements from both purification steps. The hot purification cement treatment will be modified to include a semi-continuous double acid wash, for the extraction of zinc and cadmium, followed by an alkaline wash, for the extraction and recycle of arsenic. For the cold precipitation cement, a semi-continuous single acid wash will be included. The objective is to increase the global zinc recovery by 0.3%, to decrease the arsenic trioxide consumption by 75%, and therefore, improve the quality of the copper cement. The cold purification cement treatment area will undergo an equipment redistribution because two reactors previously used for leaching the cement were refinbished and assigned to the jarosite acid wash circuit. 

In the acidic solutions, generally, a decrease in pH leads to an increase in the rate of dissolution of the less noble metal as stated above. Consequently, in the acidic solutions, a decrease in pH should lead to an increase in the rate of deposition of the more noble metal. This is seen on the examples of copper cementation on iron, aluminum, or zinc, and a schematic presentation is given in Fig. 9.4. 

Annamalai V, Murr LE (1979) Influence of deposit morphology on the kinetics of copper cementation on pure iron. Hydrometallurgy 4 57... 

Miller JD, Beckstead LW (1973) Surface deposit effects in the kinetics of copper cementation by iron. Metall Trans 4 1967... 

Karavasteva M (2005) Kinetics and deposit morphology of copper cementation onto zinc, iron and aluminium. Hydrometallurgy 76 149... 

The copper cement is obtained after drying, as a red powder in the size range... 

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