Limestone in situ characterization for Solvay soda production
Client: Solvay Italia Chimica spa
Location: San Vincenzo/ Rosignano (Livorno), Italy
The study was aimed at developing a rapid test for the characterization of the excavated rock in a limestone quarry (San Carlo quarry) before the industrial processing. The limestone is quarried to produce the Solvay soda ash (Rosignano industrial plant) and, after crushing, it is calcined (950 – 1100°C) inside the lime kilns of the plant. In the quarry, the rock looks homogeneous, but it shows a variable behaviour inside the lime kilns; in particular, some crushed limestone pieces, very sensitive to thermal effects, show bad mechanical performance in the industrial process and this rock should be previously discarded in order to avoid economic losses. Indeed, its presence in the kilns requires halting the production with economic losses estimated as approximately 1 M€/day.
Development of a rapid mechanical test:
- to characterize and select the excavated rock materials in the quarry before sending it to the industrial plant;
- to substitute the test traditionally adopted (Schmidt test), expensive (approximately 8.000 €/month) and time consuming (more than 2 hours/sample).
Design of an innovative mechanical test which can be performed in the quarry on irregular samples, reliable and able to characterize the quarried rock more quickly and at lower cost than the test traditionally adopted (Schmidt test).
- Study of the problem in order to identify the causes of the variable performance of the quarried rock in the industrial processing;
- Critical analysis of the characterization test (Schmidt test) previously adopted for the rock selection (traditional approach);
- Study of different characterization tests, alternative to the traditional approach, and evaluation of their reliability;
- Development of an innovative rapid mechanical test for quarried rock characterization on irregular samples;
- Validation of the developed procedure by performing many tests;
- Design of a survey campaign to study the spatial distribution and variability of the limestone rock in the rock mass / orebody.
Traditional approach: 96000 €/year
Total cost of the performed study: 35000 €