129 Introduction The Platreef is a geological region of the Bushveld Complex—the largest source of primary platinum group metals, PGMs, in the world. PGM mineralization in the area was first reported by Dr Hans Merensky in 1924. The operation is part of the Anglo Platinum operations Potgietersrust Platinums Limited, ‘PPL’, being a wholly owned subsidiary. The operations are situated on the Nort...

In this paper, extractants are presented which made it possible to separate actinides(III) and lanthanides from strong nitric acid solutions (0.05 1 mol/L). For this purpose, new aromatic dithiophosphinic acids were synthesised and characterised, and the distribution ratios of Am(III), Eu(III) and all relevant lanthanides were determined in batch extraction experiments. The extractant used was ...

The present thesis is motivated by chemical engineering: process simulation and optimization with a focus on distillation-based flowsheets. In this context, a process consists of a number of unit operations connected by streams. Such a structure can be represented by a so-called flowsheet. In general, the process should be designed in a way that certain engineering demands are fulfilled, e.g. p...

Case-Based Reasoning (CBR) paradigm is very close to the designer behavior during the conceptual design, and seems to be a fruitable computer aided-design approach if a library of design cases is available. The goal of this paper is to presents the general framework of a case-based retrieval system: REPRO, that supports chemical process design. The crucial problems like the case representation ...

In the light of increasing fears about climate change, greenhouse gas mitigation technologies have assumed growing importance. In the United States, energy related CO2 emissions accounted for 98% of the total emissions in 2007 with electricity generation accounting for 40% of the total. Carbon capture and sequestration (CCS) is one of the options that can enable the utilization of fossil fuels ...

This paper presents an Equality Relaxation variant to the Outer-Approximation algorithm for solving mixed-integer nonlinear programming (MINLP) problems that arise in structural optimization of process flowsheets. The proposed algorithm has the important capability of being able to explicitly handle nonlinear equations within MINLP formulations that have linear integer variables and linear/nonl...

Significant advances have been made in the last two decades for the effective solution of mixed integer non-linear programming (MINLP) problems, mainly by exploiting the special structure of the problem that results under certain convexity assumptions. This paper discusses the computational experience with a novel decomposition algorithm which is based on the idea of closely approximating the f...