[en] Previous computation of stability factors of colloidal gold from coagulation data was found to be in systematic error due to an underestimation of the particle concentration by electron microscopy. A new experimental technique was developed for determination of this concentration. Stability factors were recalculated from the previous data using the correct concentration. While most of the previously reported conclusions remain unchanged, the absolute rate of fast coagulation is found to agree with that predicted by the theory. A value of the Hamaker constant was determined from the corrected data

[en] The high-rate floc blanket clarification process developed by the Anglo American Corporation of South Africa is capable of continuously clarifying gold and uranium pregnant solutions containing 200-2500 mg/L suspended solids to below 25 mg/L solids at an average rising velocity of 8 m/h at the low process cost of R0,001-0,002 per ton of liquid treated. Overall process cost savings are mainly due to increased polishing filtration cycle times

[en] In this work an alternative method has been developed which permits to estimate the rate constant of an aggregation process of model colloids (spheric and monodisperse particles) but in an automatic and reliable way, because a longer time is considered during the aggregation process which avoid the uncertainties for the calculation of the initial slopes with very few experimental data. to reach an objective condition a limit time of 20 s was taken and it is necessary to assume a concrete form of the aggregates growing which establishes a square dependency between the optical absorbance and the time. By this fitting it is possible to estimate the coagulation rate constant which is in accordance with that obtained by conventional methods, but now the rate constant is the same and maintains a constant value for a longer time (till 20 s). (Author) 19 refs

[en] It is pointed out that for an aerosol formed initially from radioactive fuel particles and non-radioactive oxide particles and subsequently undergoing both coagulation and deposition, a calculation of airborne radioactivity based solely on the usual equation governing the particle number can lead to incorrect results. A more exact general treatment is formulated for this situation, and analytic results are obtained for a simple collision kernel. (author)

[en] Published in summary form only

[en] The performance of different polymers used to flocculate red mud particulate materials in the Bayer process can be evaluated on the basis of their efficiency to achieve adequate settling velocities and turbidity levels. In this study, three commercially available flocculants are evaluated under typical conditions found in the last washer of a Bayer plant. The different shear levels are produced by using a modified Couette flow system. Great differences are noticed in the performance of the polymers when they are compared at different dosages and at different shear rate levels. The data collected also suggests that conventional cylinder settling tests may not be adequate to measure the performance of certain types of polymers. (author)

[en] The use of radiation induced polymerization should theoritically allow to prepare better flocculants. The testings of several products prepared by such a process shows that better properties are indeed obtained: better efficiencies, lower amounts needed, better overall properties

[en] Present work is devoted to possibilities to control the sorbents properties on the aggregation stage. Therefore, the connection of kinetics and properties of final aggregates is considered.

[en] The mechanism of the cement setting is given in this work. (O.M.)

[en] A previous treatment of the behaviour of radioactive aerosols is extended to take condensation into account and to cope more accurately with a general multicomponent aerosol. It is pointed out that neglect of the modifications to the conventional approach which are developed here could lead to significant errors. The treatment is illustrated by a simple model possessing analytic solutions. (author)