6.90. An ore containing 90 wt% MgSO,-H2O and the balance insoluble minerals is fed to a dissolution tank at a rate of 60,000 lb/h along with fresh water and a recycle stream. The tank contents are heated to 120°F, causing all of the magnesium sulfate monohydrate in the ore to dissolve, forming a solution 10°F above saturation. The resulting slurry of the insoluble minerals in MgSO4 solution is pumped to a heated filter, where a wet filter cake is separated from a solids-free filtrate. The filter Problems 345 cake retains 5 lbm of solution per 100lbm of solids. The filtrate is sent to a crystallizer in which the temperature is reduced to 50°F, producing a slurry of MGSO4-7H,0 crystals in a saturated solution that is sent to another filter. The product filter cake contains all of the crystals and entrained solution in a ratio of 5 lbm solution per 100 lbm crystals. The filtrate from this filter is returned to the dissolution tank as the recycle stream. Solubility data: Saturated magnesium sulfate solutions at 110°F and 50°F contain 32 wt% MGSO, and 23 wt% MgSO4, respectively. 60,000 lb ore/h 90% MGSO,H,O/h 10% S(insoluble solids) mc lb MgSO,7H,O/h) FILTER DISSOLUTION |mp (lb/h) FILTER Makeup water, mw(lb/h) CRYSTALLIZER 50°F crystals and TANK 120°F 120°F solution solution sat'd sol'n Recycle solution, Filter cake, make(lbh) (5 lb, sol'n/100 lb S) (a) Explain why the solution is first heated (in the dissolution tank) and filtered and then cooled (in the crystallizer) and filtered. (b) Calculate the production rate of crystals and the required feed rate of fresh water to the dissolution tank. (Note: Don't forget to include water of hydration when you write a mass balance on water.) (c) Calculate the ratio Ib, recycle/lbm makeup water.
6.90. An ore containing 90 wt% MgSO,-H2O and the balance insoluble minerals is fed to a dissolution tank at a rate of 60,000 lb/h along with fresh water and a recycle stream. The tank contents are heated to 120°F, causing all of the magnesium sulfate monohydrate in the ore to dissolve, forming a solution 10°F above saturation. The resulting slurry of the insoluble minerals in MgSO4 solution is pumped to a heated filter, where a wet filter cake is separated from a solids-free filtrate. The filter Problems 345 cake retains 5 lbm of solution per 100lbm of solids. The filtrate is sent to a crystallizer in which the temperature is reduced to 50°F, producing a slurry of MGSO4-7H,0 crystals in a saturated solution that is sent to another filter. The product filter cake contains all of the crystals and entrained solution in a ratio of 5 lbm solution per 100 lbm crystals. The filtrate from this filter is returned to the dissolution tank as the recycle stream. Solubility data: Saturated magnesium sulfate solutions at 110°F and 50°F contain 32 wt% MGSO, and 23 wt% MgSO4, respectively. 60,000 lb ore/h 90% MGSO,H,O/h 10% S(insoluble solids) mc lb MgSO,7H,O/h) FILTER DISSOLUTION |mp (lb/h) FILTER Makeup water, mw(lb/h) CRYSTALLIZER 50°F crystals and TANK 120°F 120°F solution solution sat'd sol'n Recycle solution, Filter cake, make(lbh) (5 lb, sol'n/100 lb S) (a) Explain why the solution is first heated (in the dissolution tank) and filtered and then cooled (in the crystallizer) and filtered. (b) Calculate the production rate of crystals and the required feed rate of fresh water to the dissolution tank. (Note: Don't forget to include water of hydration when you write a mass balance on water.) (c) Calculate the ratio Ib, recycle/lbm makeup water.
Introduction to Chemical Engineering Thermodynamics
8th Edition
ISBN:9781259696527
Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart
Chapter1: Introduction
Section: Chapter Questions
Problem 1.1P
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Transcribed Image Text:6.90. An ore containing 90 wt% MgSO,-H2O and the balance insoluble minerals is fed to a dissolution
tank at a rate of 60,000 lb/h along with fresh water and a recycle stream. The tank contents are
heated to 120°F, causing all of the magnesium sulfate monohydrate in the ore to dissolve, forming a
solution 10°F above saturation. The resulting slurry of the insoluble minerals in MgSO4 solution is
pumped to a heated filter, where a wet filter cake is separated from a solids-free filtrate. The filter
Problems 345
cake retains 5 lbm of solution per 100lbm of solids. The filtrate is sent to a crystallizer in which the
temperature is reduced to 50°F, producing a slurry of MGSO4-7H,0 crystals in a saturated
solution that is sent to another filter. The product filter cake contains all of the crystals and
entrained solution in a ratio of 5 lbm solution per 100 lbm crystals. The filtrate from this filter is
returned to the dissolution tank as the recycle stream.
Solubility data: Saturated magnesium sulfate solutions at 110°F and 50°F contain 32 wt%
MGSO, and 23 wt% MgSO4, respectively.
60,000 lb ore/h
90% MGSO,H,O/h
10% S(insoluble solids)
mc lb MgSO,7H,O/h)
FILTER
DISSOLUTION
|mp (lb/h)
FILTER
Makeup water,
mw(lb/h)
CRYSTALLIZER
50°F
crystals and
TANK
120°F
120°F
solution
solution
sat'd sol'n
Recycle solution,
Filter cake, make(lbh)
(5 lb, sol'n/100 lb S)
(a) Explain why the solution is first heated (in the dissolution tank) and filtered and then cooled (in the
crystallizer) and filtered.
(b) Calculate the production rate of crystals and the required feed rate of fresh water to the dissolution
tank. (Note: Don't forget to include water of hydration when you write a mass balance on water.)
(c) Calculate the ratio Ib, recycle/lbm makeup water.
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