Comparison of the efficacy of oxidative processes and flocculation for the removal of colour from Eop effluent.

Up to 30% of the released colour arising from bleached kraft pulp and paper production comes from the alkaline extraction stage. This waste stream can therefore be readily targeted to remove colour at source in mills where improved colour management is required. The efficacy of five advanced oxidative treatment and physico-chemical technologies in removing colour from a typical Eop stage effluent was compared. The most effective oxidative treatment was peroxymonosulphate (79% colour removal in 15 minutes). Ozone and TAML treatments removed 74% and 58% of colour respectively within 30 minutes. In comparison, hydrogen peroxide alone was only able to remove 35% of the colour over 4 hours. Coagulation with polyaluminium chloride achieved 89% colour removal within 5 minutes. However, this treatment produced an undesirable sludge, and may cause toxicity in the treated wastewater. Overall, colour removal ability of the five technologies ranked from highest to lowest was polyaluminium chloride > peroxymonosulfate > ozone > TAML > hydrogen peroxide. Other factors, such as operating costs, feedstock modification and capital infrastructure, also need to be taken into account when selecting the most suitable colour management option.     

Superconductivity in hcp Li at high pressure

Recent experimental observations show that metallic lithium becomes a superconductor at high pressure. Here the theoretically calculated band structure as well as the superconducting transition temperature for this metal at 247 kbar pressure are reported. The band structure was obtained using the APW method. The superconducting transition temperature determined using the band structure results agrees fairly well with that measured experimentally.     

Probability method of controlling the consumption of safe life of agte parts by the limiting temperature criterion

A method is proposed for predicting the residual safe life of aircraft engine parts. It facilitates limiting temperature-based control of the depletion, during operation, of durability reserves set when designing these parts. The method is based on probability comparison of in-flight temperature maxima of the parts with limiting temperatures of their materials. The method of least squares is recommended for evaluating the parameters of distributions of in-flight temperature maxima and limiting temperatures that are described by extreme type laws. A series of integral relationships necessitating the use of numerical methods are obtained for the residual gamma-percent safe life of the parts.Translated from Problemy Prochnosti, No. 10, pp. 54–58, October, 1991.     

Production of high-strength tubes made of steels of type 15GFB

A unit for making L-class high-strength pump-compressor tubing composed of low-carbon, low-alloy steels of type 15GFB is now being used on the 140 mill in the tube-rolling shop at the Rustavi Metallurgical Plant. The steel 15GFB pump-compressor tubing made by the technology that was developed has the following service properties: σ_y = 630–670 N/mm², σ_u = 730–780 N/mm², δ = 18–22%, ψ = 55–60%, KCU = 1.6–2.2 MJ/m². The percentage of ductile fracture at room temperature is 85–95%. __________ Translated from Metallurg, No. 1, pp. 79–80, January, 2006.