Unit 1 till midterm Flashcards
What is a batch process?
It’s a process where you can only make small quantities of products
Give an examples of Batch Process
Food processing, Pharmaceuticals, Specialty Chemicals, etc.
Examples of a continuous process
Pulp & Paper, Petroleum, Fertilizers & Inorganics
Advantages of Batch type process
More cost effective for small quantities, Easy to change over alternative processes
Advantages of Continuous type process
Very large scale so high products yield, consistent in product quality because it doesn’t stop.
Disadvantages of Batch Type process
Only useful for smaller quantities cause it’s difficult to make large amount on a batch, and Variable quality because it’s not consistent on its products quality.
Disadvantages of Continuous Process
Very expensive to set up and not useful for producing small batches of product
Different occupations that are usually member of the project committee
Accountants, Lawyers, Engineers, Scientist
Process operations that are improved or tested during the “Pilot Plant” stage in the development of a chemcial industry
Product quality & yields, personnel training, energy cost savings, engineering design, safety of process
6 stages of a plant start up process.
Inert (water, steam) Actual Product
Low Low
Med Med
High High
Why is a plant start up operation performed in a progressive series of steps
Safety issue
What is a unit operation? and examples of these:
It’s a physical change: Transportation, Heat Transfer, Refrigeration, Flotation, Distillation, Filtration, Adsorption, Size reduction
What is a Chemical Conversion and examples of it:
Chemical conversion is anything that physically changes a chemical. Reduction/Oxidation,Hydrolysis, Halogenation, Polymerization, Electrolysis, Hydrogenation, Neutralization, Nitration
Why are material balance calculations carried out on bench scale experimentation?
To evaluate the analytical data. To evaluate the reliability of the experiment.
When is the experiment repeated for the material balance?
When the deviation of each parameter is analyzed is greater than 5%
What unit operation is a separation of a suspension into a supernatant clear liquid and a dense slury containing a higher cocnentration of solid?
Settling
How do you improve the settling rates?
Adding flocculating reagents. Neutralize the particle charge to form floccs that would make it settle faster.
What is the reason why tailings won’t settle?
Buoyancy. The particles need to be heavy enough fpr the gravity to drag them down. Friction and the charge on the solid particles.
What are examples of Flocculating Reagents:
Organic Polymers like Separan and Inorganic Polymers like alum.
A process where mixture of solids and fluid are separated by a layer where the soldis get retained
Filtration
What kind of filtration system that would be most likely used for the municipal water treatment plant?
Gravity Sand Filters
What kind of filtration system that would be most likely used for the removal of water from wood pulp produced in a pulp mill
rotary vacuum filters
What kind of filtration system that would be most likely used for the Primary water treatment for boiler feed water in a small in small industrial plant
Pressure sand filters
What kind of filtration system that would be most likely used for the collection of a concentrated ore sample from an aqueous slurry
Filter Press or Rotary Vacuum Filter
The main operational difference between an industrial thickener & laboratory bench scale setting experiment?
Continuous Process vs Batch Process and Mechanical rake removes sludge in thickeners
two sizing classification devices that are primaly used for large scale continuous feed operations
Surface Velocity Classifier, Spitz Kasten, Double Cone Classifier
What kind of filtration system that would be most likely used for the Fertilizers?
Belt and Pan Filters
What filtration system are continuous?
Belt and Pan Filters, Rotary vacuum filters
What unit operation is an ordered solid phase that is produced from a liquid or amorphous phase (impure) used for manufacture of salts, fertilizers, organic solids, active pharmaceuitcal ingredients
Crystallization
What kind of filter is capable of treating large volumes of water and is only useful for the removal of large particulate solids?
Gravity Filter
What kind of filter requires high pressure water flow?
Pressure filters
Major Industrial Process utilizing crystallization:
Separation (separation of BPA)
Purification ( sugar & salt products)
Concentration (Fruit juices removal by evaporation of water)
Solidification (sulfur that is extracted from oil sands)
Analysis (determining molec. structure like proteins,biochem cmpds)
What is CSD? and why is it important?
Crystal size determines the activity of the drug (ie. insulin) that’s why Crystal size distribution is important. In Pharmaceuitcal, size matters.
What variables( size, distribution, & purity of crystals) used to control crystallization?
Concentration (when increased, speeds up formation)
Temperature (Low T, increases the formation of crystals)
Solubility (it is dependent on the type of solute)
What are the stages of crystallization?
Nucleation (most imp.; sets all var. req. for crystals to form) Primary Nucleation (Occurs spontaneously; Low T, Conc. is increased) Sec. Nucleation (occurs w/ addition of seed crystal/ shear force) Crystal Growth (Factors w/c affect the crystal growth)
Why is the secondary nucleation the most desirable ?
It is because this creates more pure crystals and higher yields because of the addition of shearing force and a crystal seed.
What are the two factors that limit crystal growth?
integration of crystalline molecules/atoms in the crystal surface & transport of crystal unit from the surrounding solution to the crystal surface.
What are the types of industrial crystallization units and their applications?
Cooling Crystallizers
Evaporative Crystallization
Evaporative/Cooling crystallizers
Melt Crystallization
What’s a cooling crystallizer? and give an example of its equipment
Uses Lower T to initiate crystallization, it uses coolant instead of heat. Surface Cooled Crystallizer.
What is a evaporative crystallization? and an example of it?
It’s the most simplest and common because of its constant temperature (isothermal). It removes the solvent by increasing the solution concentration. FC and DTB are the equipments.
What are the advantages of FC and DTB?
Forced Circulation Crystallizer is Cheap, Fast, and generic
Draft Tube Baffle is better in controlling the size (separates large and small crystal sizes)
What kind of crystallization unit has high temperature solution at reduced pressure is solvent temperature affecting both concentrate and temperature?
Evaporative/Cooling Crystallizers (Adiabetic)
What Industrial crystallization unit that doesn’t use solvents in its process but instead use heat as a separating agent?
Melt Crystallization
What kind of solids can you use for melt crystallization?
The ones w/ really high thermal stability so there is not decomposition above its melting point. like molten Si for computer wafers.
Why use slow cooling for crystals of desired cmpds for pharmaceutical and food products?
to obtain a 99.99% purity using melt crystallization
A unit operation used to separate a mixture of solids into 2 or more fractons based on differences in surface properties in an aqueous medium?
Flotation
What kind of solids float out on the surface and remains as tailing in the bottom of flotation cells?
Solids that float out are hydrophobic while the ones that stay in the bottom is hydrophilic.
What reagent enhances the hydrophobic characteristics of solids? give an example.
Conditioners (collectors) and kerosene, xanthates, sulfonates.
What reagent stabilizes the froth to prevent loss of concentrate when bubbles reach the surface?
Frothers. MIBC, Pine oil, Cresylic Acid
What reagent allows for the selective separation of hydrophobic solids. can turn on/off the flotation?
pH (NaOH, HCl) and Resurfacing Agents (starch, Ba,SiO3)
What does it mean when there’s a high contact angle?
It is a hydrophobic surface. and it is a high floatability w/c is a best flotation.
What does it mean when the contact angle is low?
Hydrophilic surface and low floatability.
What is the fast method for optimizing the contact angle?
Use conditioning agent (Kerosene) and Modifying agent (NaOH)
What does a frother do?
Increases the surface tension of the bubble (froth) to stabilize it on top
mineral ores that are separating?
Pb, Ni, Fe, Cu
Why is air introduced in a flotation cell?
To float the hydrophobic material
Why is there a mechanical agitation in flotation?
It produces much more effficient and better results
