Mini-pilot scale equipment
The SOLVOMET centre is continuously investing in mini-pilot scale equipment for leaching and solvent extraction experiments, allowing to tackle upscaling issues (from the lab-scale to the mini-pilot scale level) and to assist in the development of novel, commercial solvometallurgical flow sheets. Upscaling questions that are investigated by the SOLVOMET centre include:
- How can the solid-liquid separation be done after leaching, especially in case of viscous liquids?;
- How can the solvent be recycled after leaching?;
- How can loss of solvent on the solid particles be minimised?
1. Mini-pilot scale solvent extraction studies
Batch solvent extraction processes can be scaled up to a mini-pilot scale in a continuous counter current mode in our mixer-settler set-up, with the final goal to examine the possibility of scaling up the process and/or producing larger volumes of purified metal solution. First, a flow sheet is designed to determine the number of stages and optimal aqueous-to-organic phase ratio of extraction, scrubbing and stripping based on McCabe-Thiele diagrams. Furthermore, the residence time is stablished. Next, the process is run in the mixer-settlers. Samples of each stage are taken on a regular basis to evaluate the performance and make adjustments if necessary.
The mixer settler set-up of Rousselet Robatel consists of 12 stages, that can be heated up to 80 °C using a circulating water bath. The stages are each isolated and made of PVDF. The volume of the mixer and settler chambers in each stage is 35 mL and 143 mL, respectively. The total flow rate can reach up to 6 L/h.
SX Battery 2 (MEAB)
The mixer settler set-up of MEAB consists of 27 stages in total, which can be combined into extraction, scrubbing and stripping steps according to the objected flow sheet of the solvent extraction process. The mixer settlers are made of PVDF and can be used at room temperature (heating is not possible). The volume of the settler chamber is 480 mL and a max total flow rate up to 10 L/h can be achieved depending on the physical characteristics of both phases and the behavior of the mixture.
SX Battery 3 (SX Kinetics)
The mixer settler set-up of SX Kinetics consists of a total of 16 stages, that can be used at room temperature. The stages are made from glass. The volume of the mixer chamber and settler chamber in each stage are 0.270 L and 1.050 L, respectively. The total flow rate can reach up to 10 L/h with the currently available pumps.
|Characteristics||SX Kinetics||MEAB||Rousselet Robatel|
|Temperature||Only room temperature||Only room temperature||Heatable (water or oil)|
|Use||Mini-piloting||Mini-piloting and research||Mainly for research|
|Visibility||Transparent||Opaque||Opaque but with a window in the settling chamber|
|Capacity||Mixer: 0.270 L, Settler: 1.050 L||Mixer: 0.12 L, Settler: 0.48 L||Mixer 0.035 L, Settler 0.143 L|
|Flows (depends on settling velocity)||Max flow: 10 L/h with the available pumps||Max flow: 10 L/h||Max flow: 2-4 L/h|
Another type of liquid-liquid-extraction equipment that is used in our laboratory is the Kühni ECR 32 column from Sulzer. This agitated column is useful when a high number of stages is required for the separation. It also has the advantage that it allows to work easily with almost any O/A ratio. The active height and volume is about 1.2 m and 0.9 L, respectively. It is entirely jacketed to be heated or cooled by a liquid medium and its height can be adapted by adding or removing sections. By varying the active volume, the column can be used with a total flow range of 5-25 L/h.
2. Leaching studies
The SOLVOMET mini-pilot leaching equipment includes:
- A batch leaching platform (lab 01.170): i.e. a jacketed reactor platform for temperature controlled batch leaching, with different reaction vessels (1 L and 5 L vessels, see image), optimised for use with viscous liquids (e.g. ionic liquids). (1)
- A benchtop process reactor (CHEMRxnHUB, lab 01.314) with a capacity of 5 L and a digital overhead stirrer, which is suitable for reactions on a litre scale, including solid-liquid extraction (leaching) and liquid-liquid extraction. (2)
- A high-pressure reactor (Berghof, lab 01.170), which has an effective capacity of 800 mL and is made from stainless steel. It can also be used with a PTFE liner to allow a wider range of chemical compatibility. The maximum pressure that can be achieved corresponds to 200 bar, whereas the temperature with the PTFE liner can be 230 °C and up to 300 °C without it. (3)