摘要:

AbstractThe feasibility and the mechanism of the separation of pyrochlore from associated main silicate gangue minerals such as albite and biotite in an anionic collector system, using oleic acid and sodium dodecyl sulphate as collectors, in absence and presence of Fe(III), Cu(II) and Ca(II) have been investigated. Contrary to published data, the presence or addition of salts of these cations impairs rather than improves the selectivity of both soap and alkyl sulphate flotation of pyrochlore. However, leaching of the minerals investigated by HC1 greatly promotes their selective separation owing to selective teaching of metallic sites, namely Al3+, Mg2+and Fe2+, from crystalline lattice surfaces of silicate minerals leading to the predominance of the negatively charged silicate sites. This leads to a marked sluggishness of their adsorbability of collector anions and their floatability. In contrast, leaching has almost no effect on the adsorptive capacity and floatability of pyrochlore due to the close chemical similarity of its cationic sites. Sodium dodecyl sulphate is superior to oleic acid because of its lowpKaand the predominance of its collecting anions at pH of 2. These anions possess a great affinity for the positively charged Cb and Ta sites over negatively charged silicate sites, leading to the selective flotation of pyrochlore.

ISSN:0375-9210    

DOI:10.1002/jctb.2720240802

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA nomogram for the prediction of the effective thermal conductivity of two phase porous media is presented which is constructed according to the Chaudhary and Bhandari equation based upon the geometric mean of maximum and minimum thermal conductivities. A chart estimating the effective thermal conductivity values between probable limits and a nomogram determining porosity values are also included.

ISSN:0375-9210    

DOI:10.1002/jctb.2720240803

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractIf mixtures of Ca(OH)2and quartz with Ca : Si = 1.3–2.0 are processed hydrothermally at 350 °C and 400–500 bars, the products depend on the heating rate. If this is sufficiently rapid, the main product at Ca : Si = 1.5 is kilchoanite (Ca6(SiO4)(Si3O10)); this is accompanied at Ca : Si = 1.3 by xonotlite and at Ca : Si = 2.0 by calciochondrodite. If the heating rate is slower, the main products are combinations of xonotlite, foshagite and dellaite. If the heating rate is rapid, kilchoanite is formed at 300 °C, and, if it is rapid and sufficiently finely divided quartz is used, at 250 °C; it was not obtained at 200 °C. Broadly similar results were obtained at saturated steam pressures. At Ca : Si = 1.5, 250–350 °C and 400–500 bars, kilchoanite is possibly stable relative to the other solid phases, formation of which at slow heating rates is attributed to nucleation while the temperature is rising. To obtain the fastest heating rates, a new method was used, in which water is not admitted into the reaction vessel until the working temperature has

ISSN:0375-9210    

DOI:10.1002/jctb.2720240804

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractA generalised growth rate equation is derived which relates the specific growth rate of bacteria to the concentration of a limiting nutrient in a bacterial culture. Monod's simple hyperbolic and Teissier's exponential equations are shown to be two special cases of this general equation. It is also revealed that the so‐called Michaelis‐Menten constant in Monod's simple equation is inversely proportional to the maximum specific growth r

ISSN:0375-9210    

DOI:10.1002/jctb.2720240805

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

摘要:

AbstractFerricyanide serves as an electron acceptor for the conversion of sucrose and other sugars to 3‐keto derivatives by non‐growing suspensions ofAgrobacterium tumefaciens.The rate of conversion of sucrose to 3‐ketosucrose is 4‐ to 5‐fold greater in the presence of ferricyanide than the aerobic rate. A continuous flow apparatus in which the cells are retained by a membrane filter while fresh sucrose and ferricyanide are passed through the suspension is described and has been used for study of the kinetics of ferricyanide reduction and 3‐ketosucrose production. The use of ferricyanide obviates the need for aeration for effecting this sugar transformation and has additional advantages in view of the increased rate of reaction. It is proposed that the principle may be extended to other microbial oxidations. The continuous flow apparatus may also have general applicability to study of the kinetics of product formation by non‐growing cel

ISSN:0375-9210    

DOI:10.1002/jctb.2720240806

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY

ISSN:0375-9210    

DOI:10.1002/jctb.2720240801

出版商:John Wiley&Sons, Ltd    

年代:1974

数据来源: WILEY