How do I
apply this technology in my mill?
The application of partial autocausticizing technology
involves the entire liquor cycle including chemical recovery, digester
and oxygen delignification. Normally, a trial period of six-months is
recommended and Rio Tinto Minerals can assist you in preparing for this trial. The
purpose of the trial period is to:
-
Transition to using the new
technology by:
-
Adjusting the liquor analysis
method;
-
Using regular
Neobor
makeup; and
-
Monitoring the effects on the
process and adjusting the process control, if needed.
-
Assess the performance and
economics of the technology.
The stages, tasks and recommended duration of each phase
of a mill trial are presented in the schematic below:
During the
preparation phase, consideration needs to be given to understanding and
defining the objective of the trial and how this will be tracked.
Equally important to consider during this phase is the liquor analysis
and loading system for
Neobor.
Liquor Analysis
If no adjustment is made in the existing liquor analysis
method, the ABC titration will be affected by borate as shown in these
graphs:
Three analytical methods are available for the
analysis of borate-containing liquors:
Option 1:
A modified ABC titration method with boron correction factor for on-line
or off-line
automatic
titration analysis.
Option 2:
A modified ABC titration method with boron correction factor for
manual
liquor analysis.
Option 3: An automatic
double-titration method to determine both liquor analysis and boron
concentration.
The most suitable option or options for your mill need to
be determined prior to the mill trial based on the current analysis
method, equipment and other relevant factors.
Loading Neobor into your process
Neobor
(Na2B4O7.5H2O) is the
chemical used in this application, which is a free-flowing granular
powder. Normally, loading is handled using systems that are typically
available in the mill, so there is almost no capital investment involved
for the application of this technology.
The application requires an initial charge of Neobor
to load the liquor inventory to the operating level of
autocausticizing. Daily makeup is required to compensate for losses.
Both the initial charge and the daily makeup of
Neobor
can be added almost anywhere in the liquor cycle.
For each new application, our technical team would
recommend a loading protocol in consultation with the mill
representatives.
Successful Applications
Our technical team will work with you both before and during the mill
trial to ensure a successful application of autocausticizing. The major
requirements for a successful application are:
-
Sound value proposition to utilize
autocausticizing
-
Use of the new analytical method
and adjustment of recausticizing control (if required)
-
Compatibility of recovery boiler to
burn borate containing liquor or allow optimization of the boiler
operating parameters for this purpose (if required)
-
The human factor and susceptibility
to implementing process changes
-
Understanding the typical
variability of the mill process data
-
Process stability and/or sufficient
time allowance to assess the performance of autocausticizing within
the process noise level
