SYNTHESIS OF FLOTATION BASED SEPARATION SYSTEMS
In this work a methodology is presented for defining the optimal configuration for flotation circuit and selection of appropriate equipment for the process. The problem is represented by three hierarchized superstructures. The first level represents separation tasks, which include: feed processing, concentrate processing, and tail processing. The second level represents the stream network needed to carry out each tasks. Where for each task a superstructure is developed which includes several operational stages. At the third level, several equipment alternatives are considered for each stage. The equipment discussed in the model includes flotation column and flotation cell banks, with and without grinding. The optimal selection of the circuit is made with an appropriate objective function, upon which the values of the operational and structural variables may be determined. The problem is formulated using disjunctive programming, which is converted to a MILP problem. The model includes mass balance, equipment models, operational conditions, and logic relationship. The paper presents an example to illustrate its application for effective design of a copper concentration plant.
Relation between locked cycle tests and continuous plant circuit in flotation
Abstract It is important to elucidate the relation between the locked cycle flotation test and the continuous flotation circuit because the locked cycled test has been traditionally the only way to experimentally simulate a continuous circuit. We analytically assessed the mass balances of the locked cycle test in a rougher–cleaner–cleaner scavenger (R–C–CS) system as a function of the iteration number of tests and provided an analytical expression of the mass balance in each separation stage. The mass of the final concentrate and flotation characteristic curves in a continuous circuit and the locked cycle test were calculated using the flotation rate constant k and flotation time T . Based on the comparison of the calculated results between the two tests, a good agreement between the locked cycle test and the continuous circuit can be obtained when the kT value for a product component with the flotation rate constant k and time T is in the range where the mass of a component does not change with kT .
ISOLATION OF BOVINE PARAINFLUENZA-3 VIRUS IN CHICK EMBRYOS
Myxovirus parainfluenza-3 (SF-4 bovine strain) was first isolated in tissue cultures of embryonic bovine kidney (EBK) cells (Reisinger, Heddleston, and Manthei, J. Am. Vet. Med. Assoc. 135:147, 1959). This agent is antigenically and biologically related to the human HA-1 strain isolated previously by Chanock et al. in monkey kidney cells (Abinanti and Huebner, Virology 8:391, 1959; Abinanti et al., Proc. Soc. Exptl. Biol. Med. 106:466,1961). At present, both viruses are isolated and propagated in tissue cultures, and tissue-culture products are employed for most research purposes. This investigation indicates that bovine parainfluenza-3 virus can be isolated and produced in 14-day-old embryonated hen's eggs, and that the developing chick embryo is highly susceptible to parainfluenza-3 virus infection. Isolation of parainfluenza-3 virus in chick embryos was compared with isolation in tissue cultures. EBK tissue cultures, maintained in Earle's balanced salts (BSS) with 5.0% calf serum and 0.5% lactalbumin hydrolysate (Nutritional Biochemicals Corp., Cleveland, Ohio), were inoculated with 0.2 ml of nasal-swab material (nasal swabs suspended in 4.0 ml of BSS) from 14 calves with signs of shipping fever. After incubation at 36 C for 6 days, fluids from cultures not showing cytopathic effects were subcultured in fresh cells, and the remaining monolayers were examined for noncytopathic virus by the adsorption-hemagglutination (hemadsorption) test of Vogel and Sholokov (Science 126:358, 1957). Infectious fluids from positive cultures were retained for parainfluenza-3 virus identification. Embryonated hen's eggs (14 days old) were inoculated by the amniotic route with 0.1 ml of nasalswab material. After 4 days at 36 C, the amniotic fluids were harvested and tested for virus by inoculation of EBK cells. Parainfluenza-3 virus was identified by serum-neutralization tests in tissue cultures with immune rabbit serum prepared against the original SF-4 bovine virus isolate. Parainfluenza-3 virus was isolated from six nasal-swab suspensions in both EBK cells and 14-day-old chick embryos. Five embryonated eggs and an equal number of tissue cultures were inoculated with each suspension and, in all cases, eggs were infected more frequently than were corresponding tissue cultures inoculated with larger doses of the same material. The isolation of parainfluenza-3 virus from two samples was complicated in tissue cultures by the presence of infectious bovine rhinotracheitis (IBR) virus which also produces cytopathic effects in EBK cells. IBR virus did not interfere with the isolation of parainfluenza-3 virus in embryonated eggs and was not demonstrated in amniotic fluids 4 days after virus inoculation. Noncytopathic virus, demonstrable by hemadsorption, was not isolated. When three nasal-swab samples containing parainfluenza-3 virus were diluted 1:2 and 1:20 in BSS, virus was isolated from the lower concen-