Abstract: The disadvantages of continuing industrialisation, such as environmental impacts and the
decreasing resources of natural raw materials, have to be mitigated by the development of
sustainable technologies By studying geochemical processes and properties of natural
materials, new sustainable processes can be designed This field of study is known as
Geochemical Engineering (Schuiling 1990, 1991 )
A typical example of Geochemical Engineering is the use of olivine for the neutralisation of
industrial waste acids (Schuiling et al 1986) Olivine, the fastest weathering silicate mineral,
is available in large quantities and provides an excellent buffer for naturally produced acids
The use of olivine for the neutralization of industrial waste acids is therefore appealing
Compared to conventional methods for the neutralisation of waste acids, the use of olivine
has the advantage that it produces valuable by-products, like precipitated silica and magnetic
ferrites, while it generates no new waste streams (Schuiling et al 1986) Since the olivine
dissolution rate under natural conditions is too low for industrial application, the rate must be
increased by raising the temperature or by using higher concentrations of acid or higher
olivine surface areas The properties of the first by-product, precipitated silica, depend
strongly on the reaction conditions (Lieftink 1997) A wide range of precipitated silica
qualities can be produced by varying temperature, grain size and quantity of olivine and acid
concentration The Olivine Process may, therefore, also be considered as an interesting
alternative for current production processes of precipitated silica
The Olivine Proccess for the neutralization of waste acids was invented in 1985 at the
University of Utrecht and patented (Duth Patent PCT NL 85/00026), the patent is currently
owned by Geochem Research BV From 1986-1987 research on the improvement of the
neutralization process and on applications of the neutralization products has been carried out,
supported by a grant from the Dutch Ministry· of Housing and Environment (VROM) In 1993
research continued under a project financed by the E C Brite Euram programme titled
"Olivine/Dunite for Industrial and Environmental Applications" (GR-OLIV BRE2-CT92-
0344) Part of the research carried out for this project is presented in this thesis The main
purpose of the investigations was to collect sufficient data, necessary for the design of a pilot
plant