dian starting hcl concentration for the bath is 15%, the median concentration of spent acid would average 7%. the fe concentration in the spent acid varies based on the type of rust dissolved. the reactions below depict oxidized rust (orange) and an feo (green) surface rust in steel processing. 6hcl (aq) + fe2o3 (s) → 2fecl3 (aq) + 3h2o (l) 2hcl (aq) + feo(s) → fecl2 (aq) + h2o (g) (4) (5) Spent acid Since most of the iron in spent acid solutions tests as fe (ii), the second equation predominates. Some production plants are designed with several large pickling tanks to allow extended pickling time. the primary purpose of this is to consume as much hcl as possible before disposal or treatment. another method to maximize acid Total HCI FeCl2 H20 208.00 kg/h 12.50 31.25 164.25 Figure 4. This pyrohydrolysis process handles 5 metric tons per day (m.t./d) of spent hydrochloric acid usage is employed by many push/ pull sheet and coil pickling operations. the continuous strip steel travels countercurrent to the flow of hydrochloric acid, cleaning the the Total HCI FeO H20 Scrubber Rinse water Total HCI FeCl2 H20 272.00 kg/h 0.00 6.00 256.00 Conc. refeed Total HCI FeCl2 H20 169.00 kg/h 4.00 37.00 128.00 Venturi Fuel & air Surge Total HCI FeCl2 H20 169.25 kg/h 30.25 00.00 139.00 Iron Oxide conc. 23.70 kg/h 0.00 23.70 0.00 surface of the steel. the final countercurrent pickle tank is heated to increase reactivity and consumption of the acid. in contrast, most wire, tube and metal finishing PROTECT PUMPS DRY RUNNING * CAVITATION * BEARING FAILURE * OVERLOAD MONITOR PUMP POWER * Best Sensitivity * Digital Display TWO ADJUSTABLE SET POINTS * Relay Outputs * Adjustable Delay Timers 4-20 MILLIAMP ANALOG OUTPUT COMPACT EASY MOUNTING Only 3.25 " x 6.25 " x 2 " * Starter Door * Raceway * Panel * Wall UNIQUE RANGE FINDER SENSOR * Works on Wide-range of Motors * Simplifi es Installation WHY MONITOR POWER INSTEAD OF JUST AMPS? Power is Linear-Equal Sensitivity at Both Low and High Loads NO LOAD FULL LOAD NO LOAD No Sensitivity For Low Loads FULL LOAD PUMP POWER PUMPING VALVE CLOSING VALVE OPENING NO FLUID Roaster Absorber Total HCI FeCl2 H20 Cyclone Distillate 277.30 kg/h 0.25 0.00 277.05 Clean acid Rectifier CO2 and noncombstible CALL NOW FOR YOUR FREE 30-DAY TRIAL 888-600-3247 WWW.LOADCONTROLS.COM For details visit adlinks.chemengonline.com/76991-21 ChemiCal engineering www.Chemengonline.Com June 2020 47 POWER AMPShttp://WWW.LOADCONTROLS.COM http://adlinks.chemengonline.com/76991-21 http://www.Chemengonline.Com