Greendry complete dry line from Siti B&T

The Greendry complete dry line from Siti B&T meets all the production requirements of body preparation, a department with a high demand for water, electricity and heat energy, and is able to process a range of plastic clays that cannot be used in the wet process.

The fine milling process is performed by the Dryfast^® mill range designed for grinding ceramic bodies and available in various sizes. Key technical and design characteristics include: a series of rollers that are suitably treated to withstand the typical wear of the process; high-efficiency classifiers; differentiated treatments according to the degree of abrasiveness of the clay; maximum accessibility and minimal maintenance; high energy efficiency.

The Dryfast^® range also ensures high productivity and a consistent output particle size distribution thanks to a larger grinding surface and an efficient powder separation system. The electronic system is also significant. The management software controls the performance of the variable power machine and provides an innovative adaptive diagnostics, vibration control and fault analysis system. By continuously monitoring key machine operating parameters, it is possible to perform customised preventive and predictive maintenance and obtain key data on grinding quality and the status of the machine’s main parts.

The transformation of the particles into a grain through the addition of water is the most critical step in the powder preparation process prior to the pressing stage. The Grainmix granulator consists of two different powder humidification stages and four independent humidification circuits. The water intake is varied according to the quantity of dry material introduced into the machine. A system of modulating valves allows the water flowrate to be set for each individual humidification circuit. The possibility of managing the speed, angle and power of the mixing arms over a wide range of values guarantees the machine’s flexibility and high performance in terms of particle size. Similar particle size distribution curves can be obtained to those of spray-dried product.

Grainmix is an extremely versatile solution which can create humidified or granulated powers according to production or product requirements. The low thermal and electricity consumption and low maintenance costs make this technology especially interesting.

The new Greendry dry milling and granulation line completes the Siti B&T range, which also includes wet body preparation machines. In this segment, Siti B&T Group’s continuous modular mills use two or more modules in series and are therefore able to optimise grinding parameters at every stage. This results in a significant increase in output and consequently savings in terms of electricity and heat consumption.

A continuous modular mill brings 42% electrical energy savings compared to a conventional discontinuous mill, while a conventional continuous mill achieves 33% savings with respect to a discontinuous mill. Continuous modular milling brings a significant 16% reduction in consumption even compared to traditional continuous milling. The reduction in thermal energy requirements is a result of the smaller quantity of water contained in the slip and the higher temperature of the slip exiting from the continuous or modular mills. Switching from discontinuous technology to continuous or modular milling therefore brings 10% savings in terms of thermal energy and consequently gas consumption on the part of the spray dryer. Siti B&T Group’s renovated Technology Centre can offer ceramic manufacturers a wide range of services in the field of raw materials preparation, including:

• Complete analysis of raw materials and ceramic bodies to determine their technological characteristics before and after firing and to evaluate their behaviour during firing: these analyses can be performed by both wet and dry grinding.
• Gradient firing in an electrical laboratory kiln to evaluate the firing behaviour of ceramic bodies and/or raw materials.
• Wet milling and spray drying of ceramic bodies for semi-industrial or industrial testing. The Technology Centre is equipped with a discontinuous mill and a spray dryer which it uses to perform wet process body preparation. The discontinuous mill can be filled with 400-500 kg batches.
• Dry milling and humidification (or granulation) of ceramic bodies for semi-industrial or industrial testing. As of 2016, the Technology Centre will be equipped with a pilot plant for dry milling and humidification/granulation of ceramic bodies. Productivity will be between 300 and 600 kg/h.
• Determination of particle size distribution using a Cilas 920 laser particle size analyser.
• Customer support for production plants with wet and dry body preparation.