Alumina Feeding Page (1/3)

Introduction

The Hall-Héroult-Process needs about two kilograms of alumina (electrochemical specific alumina consumption: 1.8995 kgAl₂O₃/kgAl) to produce one kilogram of aluminum. Consequently alumina must be added permanently to the cryolite electrolyte. In former times vehicles that moved for one cell to the next one executed this task. A hammer mounted on these vehicle broke the top crust and the vehicle used a container with a nozzle to feed alumina into the molten bath.
Modern hooded cells are equipped with one or several so called point feeders that consists of an alumina silo (hopper), a crust breaking device and alumina dosing unit. With these alumina point feeders the electrolysis process control system is able to add a precise amount of alumina at the wanted time. In this way the alumina concentration of the electrolytic bath is kept in the wanted limits.
On the Alumina Feeding Page you investigate the setting the point feeders (feeding frequency and feeding time period) to influence the alumina concentration in the electrolyte.

Electrolyte Properties, Cell Voltage Parameters and Data

To determine the point feeder setting AlPrg needs the electrolyte properties and cell parameters like the number of point feeders, how much alumina a point feeder adds during a feeding action (point feeder shot) or the mass of the electrolytic bath. For this purpose AlPrg keeps a separate set of these data. In the top of the Alumina Feeding page AlPrg shows some key values and parameters.

To change these values and parameters first you transfer them from the Alumina Feeding Page into the Electrolyte Properties and Cell Voltage Pages (Cell Geometry Page, Cell Voltage Page etc.). You do this by clicking on the Upload Cell Voltage Data Button.

After changing the parameters and data in the Electrolyte Properties and Cell Voltage Pages you bring them back into the Alumina Feeding Page by clicking on the Download Cell Voltage Data Button.

In the Cell Voltage and Electrolyte Properties Window you verify the Electrolyte Properties and Cell Voltage Data that AlPrg is using for the alumina feed calculation. You open this window by selecting the corresponding item in the drop down combo box.

When you click on one of the items in the Cell Voltage Electrolyte Properties Data Window AlPrg execute first an upload of the Feeding Phases Data into the Cell Voltage and Electrolyte Properties pages and shows the the page corresponding to the clicked item.
The next figure shows the result when you clicked on the superheat line and the on the New Vertical Tab Group Button:

In this way you can easily check and modify the cell voltage and electrolyte properties data AlPrg is using for its alumina feeding calculations.