You have learn how to weight up with Barite and Calcium Carbonate from previous posts. Sometimes, you may need to weight up to extremely high weight therefore you may consider using Hematite , its average specific gravity +/- 4.8, to weight up your mud system. If you are interested in Hematite information, please take a look at Wiki.
The concept of weighting up calculation with Hematite is as same as the concept of weighting up with Barite and Calcium Carbonate. The only one thing change is weight factor used in the equation. Please follow the equation below for calculating how many sacks required to weight up per 100 bbl of original mud.
Sacks of Hematite per 100 bbl of mud = 1680 x (W2 – W1) ÷ (40 – W2)
Where; W1 = current mud weight in ppg
W2 = new mud weight in ppg
Example: Determine the number of sacks of Hematite per l00 bbl required to increase the density from 10.0 ppg (W1) to 13.0 ppg (W2):
Sacks of hematite per 100 bbl of mud = 1680 x (13.0 – 10.0) ÷ (40 – 13.0)
Sacks of hematite per 100 bbl of mud = 186.7 sacks
If you have total volume of 500 bbl of mud, calcium carbonate required to increase mud weight from 10.0 ppg to 13.0 ppg is 933.3 sacks (186.7×500/100).
Ref: 
Formulas and Calculations for Drilling, Production and Workover, Second Edition
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