Loading presentation...

Present Remotely

Send the link below via email or IM


Present to your audience

Start remote presentation

  • Invited audience members will follow you as you navigate and present
  • People invited to a presentation do not need a Prezi account
  • This link expires 10 minutes after you close the presentation
  • A maximum of 30 users can follow your presentation
  • Learn more about this feature in our knowledge base article

Do you really want to delete this prezi?

Neither you, nor the coeditors you shared it with will be able to recover it again.



No description

Asad Ahmed

on 16 July 2014

Comments (0)

Please log in to add your comment.

Report abuse


NP Plant Block Diagram
CC slippage



Filtration Losses

AN losses
Steps to be taken for reducing:
CC Slippage
AN losses
Understanding on Plant process and critical parameters.
Got involved in daily plant monitoring.
Issuance of daily monitoring report.
Gathered Data and drafted TMP report for 2nd half of 2013.
Production Loss Reports.
Direct Bagging Tests
Regular and active participation in Plant morning Meetings
Raw Materials:

Temp : 65 ~ 70 deg C
Residence Time: 85 mins
Nitric acid is kept in excess as Free acid

Inerts are removed through centrifuges.

CN Section
CN from NP section is pre-neutralized.

The CN is then converted into AN and CC in 2 stages:

NH3 + CO2 --> (NH4)2CO3 (AC)

AC + CN --> AN + CC

Washing I
Pressing I
Washing II
Pressing II
Air drying
Cake discharge
PF Working Cycle
Filtration Issues
High Lime slippage in filtrate (AN)
High AN content in lime cake
High moisture in lime cake

PF Designed For
Particle size Distribution (50% = 50 µm)

PH ~ 7.0

Temp ~ 60 - 80°C

Particle Size Distribution - 97% below 38 µm

pH ~ 8.3

Temp ~ 47.2°C

Slurry Parameters
(Design vs. Actual)
Moisture in Cake
Performance Parameters
AN content in Cake
Performance Parameters
CC content in filtrate
Performance Parameters
Avg. 1000ppm
Lime Slippage
Working Cycle:

Filtration cycle 390 sec
Max CC slippage 65 sec – 150 sec

(Based on Experiment)
CC slippage - Reasons
The major factor leading to poor filtration

PSD has direct effect on
CC slippage
cloth choking
cake moisture

More porous cake is more easier to wash and dry.

CC Slippage- After Effects
Heavy scaling in AN pre-heaters.
Lime sludge accumulation in AN tanks
NA dosing in 17-2009

NA dosing in 17-2102 A/B
17-2106 Tube failure

To reduce CC slippage
Incorporation of a 30s pre-filtration step. (70-100s)
Extensive study to enhance PSD of lime ppt.
Better understanding on 2 stage CN conversion technology.
Improve slurry parameters.
Work out on new recipe times and filter cloth based on improved parameters.
AN loss - Reasons
Cake wash-I
(57% AN)

Cake wash-II

(0.2~0.8)% AN

Lime size too fine--> cake non-porous

Cake washing tank size--> limiting
High AN in Lime
High AN in Wet Lime
When AN is >2% in Wet Lime

About “
PKR 22,863,600
” worth of HNO3 and NH3 in the form of AN is lost every year
Nutrient Losses
HNO3 and NH3 in the form of AN
Lime is Dumped

Dumping AN
safety hazard

Cut-down AN in wet lime
AN conc in cake washing-I liquor should be under 45%
Condensate for Cake wash-II should be free of AN
Cake wash-I tank to be re-sized to avoid overflowing during adequate cake washing.
Increase pressing & air drying pressures
Enhance PSD of lime, cake should be porous for the filtrate to pass through.

Nutrient losses in terms of Money
Wet lime wasted each day on avg. ~ 440MT/day
An avg. of 3% AN is wasted every day with wet lime.
Loss of AN with 3% AN in wet lime per day ~ 13.2 MT/Day
Avg. Cost of AN dumped everyday : PKR 62,640/Day
Per year we dump

worth of AN!!!

Adapt permanent acid washing scheme to improve overall filtration!!!
Asad Ahmed

GTE, NP Process
Technical Services Department

Within 2 months of joining:
Rock Phosphate
Nitric Acid
Dissolving Section:
6HNO3 + Ca3(PO4)2 --> 3Ca(NO3)2 + 2H3PO4
-CN formed needs to be filtered out:

-CN is highly soluble in water

-It is crystallized out by cooling the dissolving solution to 0~5 deg C

-RDVF's are installed for separating CN from the suspension.

NH3 is used to neutralize the mother liquor:
The lean NP solution (75%) formed is then concentrated to 99.5% in NP melt evaporators
> CC and AN formed are separated through PF

> (60~62)% AN formed is then concentrated to 92% in FFE

> 92% AN is then exported to CAN
CC separated in PF is dried and sent to CAN plant
Improper cake washing-->
CAN Plant spends ~

PKR 112,420,000/Year

to buy its lime
Environmental issues
Loss of Money
Full coverage of ATA’14 as a process engineer
Optimized cooling water in NP & CN plant
Coverage of major test runs:
NP plant PTR at full load
NA dosing in 40-2069
RP new recipe with 2% Turkish rock blend
CWBP test run
Problem analysis of some major plant issues
NP evap vacuum drop issue
PF filtration issue
Got validated for PSM with distinction
Participated in some major activities at other plants e.g. Cooling Tower test run.
Audit of safety showers and eye washers at NP plant, highlighted those which were not meeting ANSI requirements.
Practiced and encouraged safe working throughout.
Achievements as a GTE
Lime formed is too fine (97% < 38 µm)
Mother Liquor mainly contains H3P04 and HNO3

At the end of neutralization NP solution forms

Which is a mixture of several compounds:
Full transcript