FilmTec Technical Manual - Chester Paul Company

2.4.4 Barium Sulfate Scale Prevention /8/Barium sulfate is the most insoluble of all alkaline-earth sulfates. When present in water, it may lead to massive precipitation,possibly acting as a catalyst for calcium sulfate and strontium sulfate scaling.In most natural waters, barium is present at a level that would cause barium sulfate precipitation in the concentrate stream.The critical feed concentration of barium may be as low as < 15 µg/L in seawaters, < 5 µg/L in brackish waters or even < 2µg/L if sulfuric acid is dosed to brackish waters.Calculation /8/Prediction of BaSO 4 scaling potential is performed in the same way as the previously described procedure for CaSO 4 .1. Calculate the ionic strength of the concentrate stream (I c ) following the procedure described in Section 2.4.1:⎛ 1 ⎞Ic= If ⎜ ⎟Eq. 5⎝1−Y ⎠2. Calculate the ion product (IP c ) for BaSO 4 in the concentrate stream:⎡ m 2+⎛ 1 ⎞⎤⎡m 2−⎛ 1 ⎞⎤IPc= ⎢( Ba )f ⎜ ⎟⎥⎢( SO4)f ⎜ ⎟⎥ ⎣ ⎝ 1−Y⎠⎦⎣⎝ 1−Y⎠ ⎦where:( m Ba 2+ ) f = M Ba 2+ in feed, mol/L( m SO 42–) f = M SO 42–in feed, mol/L3. Compare IP c for BaSO 4 with the solubility product (K sp ) of BaSO 4 at the ionic strength of the concentrate stream, Figure2.7. If IP c ≥ K sp , BaSO 4 scaling can occur, and adjustment is required.Adjustments for BaSO 4 Scale ControlThe adjustments discussed in Section 2.4.3 for CaSO 4 scale control apply as well for BaSO 4 scale control.2.4.5 Strontium Sulfate Scale PreventionCalculation /8/Prediction of SrSO 4 scaling potential is performed in the same way as the previously described procedure for CaSO 4 :1. Calculate the ionic strength of the concentrate stream (I c ) following the procedure described in Section 2.4.1:⎛ 1 ⎞Ic= If ⎜ ⎟Eq. 5⎝1−Y ⎠2. Calculate the ion product (IP c ) for SrSO 4 in the concentrate stream:⎡ m 2+⎛ 1 ⎞⎤⎡m 2−⎛ 1 ⎞⎤IPc= ⎢( Sr )f ⎜ ⎟⎥⎢( SO4)f ⎜ ⎟⎥ ⎣ ⎝ 1−Y⎠⎦⎣⎝ 1−Y⎠ ⎦where:( m Sr 2+ ) f = M Sr 2+ in feed, mol/L( m SO 42–) f = M SO 42–in feed, mol/L3. Compare IP c for SrSO 4 with the solubility product (K sp ) of SrSO 4 at the ionic strength of the concentrate stream, Figure2.8. If IP c ≥ 0.8 K sp , SrSO 4 scaling can occur, and adjustment is required.Adjustments for SrSO 4 Scale ControlThe adjustments discussed in Section 2.4.3 for CaSO 4 scale control apply for SrSO 4 scale control as well.Page 40 of 180 ® Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow Form No. 609-00071