Grinding Behavior and Potential Beneficiation Options of Bauxite Ores

This laboratory study investigates selective grinding and beneficiation options for a Greek bauxite ore. First, a series of batch grinding tests were carried out in order to investigate the grinding behavior of the ore and the effect of the material filling volume (fc) on the distribution of aluminium- and iron-containing phases. Then, the ground ore was subjected to magnetic separation either as received or after reduction roasting in order to further explore potential beneficiation options. The results showed that grinding of the ore exhibits non-first order behavior, while the breakage rate varies with grinding time. Additionally, Al2O3 tends to concentrate in the coarser than 0.300 mm product fraction, while fc 10% and 2 min of grinding time are considered optimum conditions for good distribution of Al2O3 and Fe2O3. When different product fractions were subjected to magnetic separation, it was seen that the non-magnetic product obtained from the 0.300–1.18 mm fraction was more rich in Al2O3. In this fraction, the Al2O3 content increased from 58 wt% in the feed to 67.9 wt%, whereas the Fe2O3 content decreased from 22.4 wt% in the feed to 13.5 wt%. When the ore was subjected to a two-step treatment, involving reduction roasting followed by magnetic separation, the Fe2O3 grade decreased from 20.8 to 5.1 wt%, but in this case the recovery was very low.

Lightweight sintered aggregate as construction material in concrete structures

The paper presents the result of testing a new patented lightweight aggregates. The only solid material used to manufactured these aggregate is fly ash. Lightweight sintered aggregate is durable, lightweight and high-strength material. It is environmentally friendly material. It has chance to by future material in concrete use. The laboratory test shown that the concrete made from the this special lightweight sintered aggregate possesses low porosity, high strength and high durability potential. The bulk density, depending on the product fraction, oscillates between 550- 830 kg/m3. This special lightweight sintered aggregate has also high resistance to crushing, when we compare to another lightweight aggregate.

Properties of Fibrinogenolysis and Fibrinolysis Products in Immune Assays

SummaryAn evaluation of split products derived from fibrinogen and fibrin gave the following results:1. Fibrinogen can be assayed in the presence of split products by the following techniques: Fibrinogen assay according to Ratnoff and Menzie and immuno radial diffusion after heat precipitation. Using the thrombin clotting time the recovery is improved if the incubation time is extended up to 24 hrs and further by adding Ca ions.2. On immune electrophoresis split products separate only in serum but not in plasma. If however, euglobulin fractions and acidified plasma were prepared separation occured.3. The larger split product, fraction D, derived from fibrinogen is heat labile, whereas it is heat stabile if it is derived from fibrin. Thrombin as well as large concentrations of plasmin stabilize the split product from fibrinogen against heat.4. The prolongation of thrombin clotting time in the presence of fibrinogenolysis split products disappears after heating. Split products derived from fibrin do not prolong the thrombin clotting time. A prolongation however, develops after heating.5. It is suggested that differentiation between intravascular coagulation and proteolysis is possible on the basis of the combined techniques of immune electrophoresis, radial diffusion method and the thrombin clotting time before and after heating.

DARSTELLUNG VON GONADOTROPIN AUS MENSCHLICHEN HYPOPHYSEN

ABSTRACT Approximately 3000 human hypophyses were processed by a modification of the method of König & King (1950) in order to obtain potent gonadotrophic extracts. The final product, fraction E3, was found to have a total gonadotrophic activity of 200 HMG U./mg in the mouse uterus test and was 10 times as active as the FSH standard NIH-FSH-S 1 in the HCG augmentation test. MSH, ACTH and LTH contamination was insignificant. The specific activities obtained in other laboratories (Gemzell et al. 1958, 1960; Li 1960; Steelman et al. 1953, 1958, 1959) are not substantially higher. It may therefore be concluded that our relatively simple procedure is just as efficient as the more complicated, time consuming methods referred to above. Furthermore the overall recovery of our method seems to be higher. Attempts were made to obtain a further purification of fraction E3 by means of CMC, Sephadex and DEAE-Sephadex chromatography and also by means of flow-stream electrophoresis. DEAE Sephadex chromatography results in a slight increase in specific activity, which was, however, combined with a substantial overall recovery loss. The other fractionation methods employed gave no satisfactory results. A complete separation of FSH and ICSH activity even by means of CMC chromatography was not obtained. The total gonadotrophic activity per hypophysis was found to be approximately 1000 HMG units (average in unselected batches of hypophyses from various pathology institutes). Estimation in single hypophyses of men and women above the age of 45 resulted in higher values. Single estimations of total gonadotrophin activity in hypophyses of foetuses and of pregnant women have very low values, while in the hypophyses of children no gonadotrophic activity could be detected.

The decomposition of n -hexane II. By reaction with atomic hydrogen

The reaction of hexane with hydrogen atoms produced by mercury photosensitization, has been studied in a flow system at 300° C. About one-third of the products had molecular weights greater than that of hexane, and dodecane was the main component of this product fraction. Hydrogen: hexane ratios up to 55:1 were employed and in these conditions virtually all the quenching of excited mercury atoms was brought about by hydrogen. The activation energy and steric factor of the reaction C 6 H 14 + H = C 6 H 13 + H 2 are estimated at 6 kcal and 10 -4 , respectively. These values are in accord with those recently obtained for the corresponding reactions involving other n -paraffins. The initial product distribution was similar to that obtained in the mercury photosensitized decomposition of hexane and the findings suggest that products of lower molecular weight than hexane derive almost completely from thermal decomposition of hexyl radicals. ‘Atomic cracking’ appears to be of little importance at these high temperatures.