University of Bahrain

College of Engineering

Department of Chemical Engineering

(CHEG 413)

Unit operation laboratory

Experiment 4

Extracting of copper sulfate from sand by using water solvent in liquid-solid extraction

Done by:Ahmed sameer, 20073435 Supervised by: Dr. Fatma Marhoon

expirement Date: 02/04/2012

Submission Date: 12/04/2012

Semester I, 2011-2012

Abstract

Copper sulfate was extracted from sand in liquid-solid extraction process by using water solvent. The water is evaporated and then condensed to ensure its purity. The concentration of copper sulfate was determined by using ultraviolet spectrometer. The amount of copper sulfate before extraction was chosen to be 7 grams and the amount determined before extraction was founded to be 6.153 grams with recovery yields equal to 87.91%. The error between experimental value and the ideal value was founded to be 12.08% which can be considered as acceptable value. However the amount of extracted copper sulfate can be increased by using higher selectivity solvent and by added agitator to increase its solubility.

2 | P a g e

Table of Contents

Abstract....................................................................................................................................2

I.Introduction and Background.................................................................................................4

II.Theory....................................................................................................................................5

III.Industrial Applications..........................................................................................................6

IV.Apparatus and Procedures...................................................................................................7

IV.1 Apparatus......................................................................................................................7

IV.2 Material......................................................................................................................7

IV.3 Procedure......................................................................................................................7

V.Results and disscusion...........................................................................................................8

VI.Conclusions and Recommendations.....................................................................................9

VII.References.........................................................................................................................10

VIII.Appendices.......................................................................................................................11

A. Raw Data........................................................................................................................11

B. Sample Calculations........................................................................................................12

C. Nomenclature.................................................................................................................13

3 | P a g e

I. Introduction and Background

Liquid-solid extraction or leaching is the separation of a solid solute from a mixture of solids by dissolving it in a liquid phase the solution is then split into two layers. The external solution is called extract and the internal one raffinate. Basically, there are three components in leaching: solid solute, insoluble solids and solvent.

Liquid-solid extraction is one of the oldest unit operations in the chemical industries. By far the most universal and ancient form of extraction is the brewing of tea or the making of coffee. In the tea example, the hot water is the solvent which extract the coffins. Many products like Vegetable oils, sugar, medicines from medicinal plants, etc. are made by processing solid starting material using extraction with liquid solvent. [1]

The performance of extraction process is depending on the extracted amount. In this experiment a mixture of copper sulfate and sand will be separated by using water solvent. The amount of extracted copper sulfate will be determined by using ultraviolet spectroscopy and then the recovery yield will be calculated. [2]

4 | P a g e

II. Theory

When a liquid solvent is added to a mixture of solids, the solid which have a high solubility in the solvent will be separated from the other solid as shown in figure 2-1. The mechanism of solid liquid extraction is:

1- The solvent diffuses into the solid phase2- The diffused solvent dissolves the solutes and transfer it to liquid phase

Since the solution layer which contain the solvent and the extracted solid have less density than the other layer it will be formed at the top. Then the two layers can be separated by gravity or vacuum filtration

Leaching is always followed by solvent recovery, which involves another mass transfer operation; such as filtration.

Figure 2-1: mechanism of solid-liquid extraction

The separation process is not ideal and part of the solid will not dissolved in the solvent. The performance of solid-liquid extraction process is expressed in term of yield recovery which is the ratio between the amount of extracted solid and the original amount of solid before extraction take place.For extracted solid, the yield recovery is written as:

R=MCV fF (m )

(100 ) … Equation (2-1)

Where R is the yield recovery, M is the molecular weight of, C is the concentration, V f is the final volume of the solution, m is mass of solids mixture and F is the weight percent of extracted solid in the original solids mixture. [2]

The error can be calculated from the deviation of ideal value:

er ror%=F (m)−MCV f

F (m )(100 ) … Equation (2-2)

The concentration of the extracted solid can be determined by using different techniques. One of these techniques is using ultraviolet spectrometer instrument. A light will pass through the solution and part of it will be absorbed. According to the Beer-Lambert law , the absorbance of a solution is directly proportional to the concentration of the absorbing

5 | P a g e

species in the solution and the path length. By determining the absorbance of the solution and using calibration curve the concentration can be calculated. [3]

III. Industrial Applications

Heap leachingHeap leaching is an industrial process for extracting precious metals and minerals by dissolving them from ore with liquids. The process is commonly used to extract metals such as gold, copper, and uranium yellowcake in addition to several other minerals. Heap leaching is usually carried out in the open and on slightly sloping ground covered with a watertight plastic sheet or clay layer onto which a heap of crushed ore is placed. The heap is sprayed with the leaching solution which percolates or flows down through it and dissolving and carrying away the metals as it goes. The solution is then collected, sent to a processing plant for treatment to separate the valuable elements, reconditioned, and sent back to the heap for another cycle (see figure 3-1). [4]

Figure 3-1: heap leaching process to extract uranium from ore.

Other applications:

1-  Removal of sugar from sugar beets using water as the solvent.2- Medicine industry.

6 | P a g e

IV. Apparatus and Procedures

IV.1 ApparatusThe liquid-solid extractor unit consists of an electrical heater and a condenser which they used to evaporate and condense the solvent to make it pure. A temperature controlling system used to control the temperature in the heater and condenser. The extraction process takes place in the extractor vessel where the solids mixture placed inside and water droplets fall from the condenser (see figure 4-1). [5]

IV.2 materialIn this experiment the solute is copper sulfateCuSO 4, the insoluble solid is sand and the solvent is water

IV.3 Procedure1- Prepare a solid mixture contain 8 gram of CuSO4 and sand.2- Place the mixture inside the extractor vessel.3- Set the water temperature to 100 Celsius (evaporation temperature) and wait until

the temperature readings reach the set point, it may take 2 hours.4- The extraction process will take place and the color will change to be blue.5- Close the water flow and stop the extraction process when the vessel becomes full.6- Use UV spectrometer to determine the concentration of copper sulfate.

Figure 4-1: block flow diagram of liquid-solid extraction unit

7 | P a g e

Heater

Condenser

Extraction vessel

Solvent

Solid mixtures

raffanite extract

condensatevapor

V. Results and discussion

Table 5-1: experiment results

Amount of CuSO4 before

extraction (g)

concentration of CuSO4 (mol/L)

Final solution volume

(L)

Amount of CuSO4 after extraction( g

)

Amount of unrecovered

CuSO4 (g)

Recovery yields%

Error%

7 0.038552 1 6.153 0.847 87.91 12.08

The amount of copper sulfate in the solids mixture was chosen to be 7 grams. The concentration of extracted solid was determined by UV spectrometer to be 0.038552 mol/L. the amount of extracted solid was determined to be 6.153 grams and the amount solids which was not recovered is 0.847 grams. The recovery yield which is calculated by using equation (2-1) is 87.91%. The error between extracted value and ideal value is 12.08%. The error is acceptable since most of the copper sulfate is extracted. Source of error in this experiment may from the fitted calibration curve and the Wight of the solid mixture.

8 | P a g e

VI. Conclusions and Recommendations

To conclude, copper sulfate was extracted by water solvent from sand. The recovery yields were founded to be 87.91% and the amount of extracted solid was founded to be 6.153 grams. The experiment was very helpful and we learned about two units, the extraction unit and UV spectrometer unit. The amount of extracted solid can be increased by using high selectivity solvent if it’s available. Adding agitator to the extraction unit may increase the solubility of copper sulfate in the solvent. Using more accurate balance may decrease the results error.

9 | P a g e

VII. References

1- Wikipedia “leaching chemistry” http://en.wikipedia.org/wiki/Leaching_(chemistry)

2- J. D. Seader, Ernest J. Henley, "Separation Process Principles 2nd Edition" W iley | 20053- Wikipedia “ultraviolet” http://en.wikipedia.org/wiki/Ultraviolet

%E2%80%93visible_spectroscopy4- wisegeek “ what is heap leaching” http://www.wisegeek.com/what-is-heap-

leaching.htm5- The laboratory manual which is handled by the instructure.

10 | P a g e

VIII. Appendices

A. Raw Data

Before extraction: weight of the copper sulfate = 7 g

After extraction: volume = 1 L, Absorbance = 0.401 A

Molecular weight of copper sulfate= 159.62 g/mol

Table A-1: UV spectrometer calibration curve data

Con. (M)

abs. (A)

0.18 1.9890.144 1.4870.108 1.1250.054 0.5550.036 0.3530.018 0.2340.0098 0.094

0 0.5 1 1.5 2 2.50

0.020.040.060.08

0.10.120.140.160.18

0.2

f(x) = 0.092427246088328 x + 0.00147173779748988R² = 0.996500971608163

Concentration vs Abs

Absorbance (A)

Conc

entr

ation

(M)

Figure A-1: UV spectrometer calibration curve.

11 | P a g e

B. Sample Calculations

The relationship between the absorbance and the concentration from linear curve fitting as shown in figure A-1 is:

Y=0.092 x+0.001

Substituting by 0.401

Y=0.092 (0.401 )+0.001=¿0.038552

Using equation 2-1 to calculate recovery yield:

R=MCV fF (m )

(100 )

R=159.62 (1 )(0.038552)

(7)(100 )=87.91%

Amount of extracted = 6.153 g

error%=7−6.1537

(100 )=12.08 %

12 | P a g e

c. nomenclature

R : recovery yieldC : concentration of extracted solidM : mass of solids mixture F : fraction in weight of solute in the mixtureVf : final volume of the solution

13 | P a g e