1. Improving BSO Services and SME Performance Through Cleaner Production
[SPEAKERS NAMES]
[DATE]

2. Module 3: A closer look at the Cleaner Production process

3. “Midland Metals” Enterprise Profile: CASE STUDY country Zimbabwe
sector
Foundry
ownership
Family-owned
established
1998
employees 16
revenue
US $65,000
Based on case study created by the United National Environment Program, Division of Technology, Industry and Economics
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

4. Background: What is a Foundry?
Midland Metals CASE STUDY
Background: What is a Foundry?
A foundry is:
a factory that pours molten metal into molds, producing cast metal objects.
Casting is one of the oldest industrial processes
There are different casting processes. The focus here is: “GREEN SAND” CASTING
Aluminum pots
Engine blocks,
axles
Some typical cast metal objects:
Turbine blades in jet engines
“low tech” “high tech”
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5. Background: SAND-CASTING
Midland Metals CASE STUDY
Background: SAND-CASTING
Basic materials & equipment for green sand-casting
Pattern
(a copy of the shape you want to produce, made of wood, plastic or metal)
Sand, mixed with clay binder & water (so it will hold its shape) plus coal dust to improve surface finish
The pattern must be slightly larger than the finished part you want to produce, as metal shrinks when it cools (about 10mm/meter, depending on the lengh)
Container of molten metal (filled from furnace)
Top and bottom mold forms (made of metal, open at top and bottom)
Rammer (tool to compact the sand; often a pressing machine is used)
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6. Background: SAND-CASTING
Midland Metals CASE STUDY
Background: SAND-CASTING
A very basic summary of the sand casting process. . .
First of all, mix the sand.
THEN 1
MOLDING: Sand placed into bottom mold form & compacted 2
MOLDING: Pattern placed into mold
STRONGLY SUGGEST that presenter be prepared with props:
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7. Background: SAND-CASTING
Midland Metals CASE STUDY
Background: SAND-CASTING
MOLDING: Add the top mold form 3
A tube or pipe provides a path to pour the metal in
Note that the top form and bottom form lock together; they always fit together the same way!
Pattern is still inside! 4
MOLDING: Fill top form with compacted sand.
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

8. Background: SAND-CASTING
Midland Metals CASE STUDY
Background: SAND-CASTING
In the middle of the sand is a cavity shaped like the pattern!
MOLDING: Take the top mold off and remove pattern & pipe or post 5
Pouring hole
In “dry sand casting,” the molds filled with sand are baked to increase the strength of the sand. In green sand casting, the water with which the clay is mixed is not evaporated. 6
MOLDING: Replace the top mold and fasten securely!
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

9.  Background: SAND-CASTING
Midland Metals CASE STUDY
 Background: SAND-CASTING
Sometimes the molds filled with sand are baked to increase the strength of the sand 8
Wait for the metal to cool (minutes to days, depending on the size of the casting) 7
CASTING: Pour the metal (container is filled from furnace immediately before you are ready to pour)
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

10. Background: SAND-CASTING
Midland Metals CASE STUDY
Background: SAND-CASTING
A copy of the pattern has now been made in metal 9
CLEANING. Sand is cleaned off the part, the “tab” where metal flowed in must be removed.
For very large parts, sand set on the shop floor forms the bottom half of the mold. This is “floor molding” 10 8
SHAKE OUT: Break apart the two halves of the mold & take out the part—usually requires vibrating or striking the mold to break apart the sand
Mold forms are reused
Sand is broken up, screened to remove debris and clumps, and sent for remixing 11
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11. Background: SAND-CASTING
Midland Metals CASE STUDY
Background: SAND-CASTING
Sand-casting is simple in concept, but demanding in execution. It is a process essential to making basic and advanced products. . . it is also hazardous and energy-intensive!
Key hazards: burns, silicosis (from inhalation of dust), toxic fumes when organic binders are volatilized by molten metal.
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

12. Midland Metals Enterprise Profile, cont’d:
Midland Metals CASE STUDY
Iron mill balls & crushing hammers (used for crushing ore)
products
Production volume
25 tons/month (planning 10-fold expansion)
Markets
Mining sector
Trainer should explain how the products are used
3-15cm
(mill balls)
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13. Midland Metals CASE STUDY Shake-out & Cleaning area
Foundry process map
Sand (new/old), bentonite*, coal dust, water, energy
Dust, gases, noise, reject mixed sand, surplus sand
Sand mixing area
Patterns, mold forms, sand filling, coatings, energy
Molding section
Dust, gases, surplus sand, noise, rejected molds
Molding Section
liquid metal
Gases, organic fumes
Casting area
Note that the various steps of the production process are just as we described them
Shake-out & Cleaning area
Dust, gases, mold forms, used sand
Energy
Non-Product OUTPUTS
INPUTS
Finished products
*Bentonite is a mineral clay. It forms a binding agent when mixed with water.
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

14. Initial CP assessment findings
Midland Metals CASE STUDY
Initial CP assessment findings
Sand contains significant amount of dust
Wind blows sand and dust from stock piles
Workers estimate quantities for sand binder and hardener
Energy consumption of furnaces higher than normal for similar operations
Furnace tap-hole not well sealed after use
Liquid metal spills during filling of molds
Large number of rejects
Sand is lost in each cycle
Sand mixing and reclamation very labor intensive
#8 & #9—quantifying these issues required more detailed assessment, carried out later.
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

15. Material balance for sand mixing
Midland Metals CASE STUDY
Material balance for sand mixing
INPUTS
OUTPUTS
Energy
- Electricity = 6 MWh
SAND MIXING PROCESS
(mostly manual)
Emissions to the atmosphere
- Dust = 30 t
Raw materials
- New sand = 135 t
- Old sand = 540 t
- Coal dust = 55 t
- Bentonite = 55 t
- Water = 40,320 litres
Waste
- Used sand = 105 t
Moulds and cores are made of sand
Products
- Moulds and cores = 672 tonnes !
only 75% reclamation efficiency (25% of sand in each batch is lost.)
Annual figures
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16. Sand Mixing: Raw materials costs
Midland Metals CASE STUDY
Sand Mixing: Raw materials costs
Input
Quantity per 50 kg batch (kg)
Annual quantity* (kg)
Unit cost (US$/kg)
Annual Total cost (US$)
New Sand 10
134,400
0.02
2,677
Old Sand 40
537,600 -
Bentonite 4
53,760
0.17
9,027
Coal Dust
0.07
3,673
Water
3 litres
40,320 litres
840
Total
16,217
(*56 batches/day x 240 days/yr) !
New sand = 17% of raw material costs
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17. Biggest CP opportunities
Midland Metals CASE STUDY
Biggest CP opportunities
Waste of raw material (sand)
During mixing stage
Spillage
Dust
Inefficient use of labor
Manual sand mixing
Manual screening for sand reclamation
RESULT: 4 man-hours required to mix 1 batch !
25% loss = 2000 kg sand per ton product
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

18. Rapid payback CP opportunities
Midland Metals CASE STUDY
Rapid payback CP opportunities
Annual savings (US$) 
Good housekeeping
Cover the new sand 278
Implement more thorough inspection, segregation of incoming scrap 116 
Input substitution
Use sand with low dust content 232 
Better process control
Optimize furnace-melting conditions 139
Train workers to properly handle and measure sand binder & hardner 185 
Equipment modification
Improvise proper closing mechanism for furnace taphole 28
Install goods spouts on melting pots 28
Total annual savings: $1005
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19. Capital investment CP opportunity: Mechanical sand reclamation/mixing
Midland Metals CASE STUDY
Old system:
Manual sand reclamation & mixing
Molds shaken out
Roller sand mixer + accessories + shipment
$8,106
Sand shaker
$3,706
Sand screen below the shaker
$347
2 x 5 kW motor
$926
10 m conveyor belt
$694
Other construction material
$463
Sand storage hopper
$1,158
Installation costs
$810
Contingencies
$1,621
TOTAL INVESTMENT COST
$17,833
Shaker table with Screen
(Removes lumps)
Conveyor
Belt
(Transports sand)
New system: Mechanical sand reclamation plant
Hopper
(Feeds sand to mixer)
Mechanical Sand Mixer
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20. NEW sand mixing material balance
Midland Metals CASE STUDY
INPUTS
OUTPUTS
SAND MIXING process
(mechanized)
Energy
- Electricity=24MWh
Emissions to the atmosphere
- Dust = 15 t
was 30 t
Increase from 6 MWh
Waste
- Used sand = 50 t
was 105 t
Raw materials
- New sand = 65 t
- Old sand = 610 t
- Coal dust = 55 t
- Bentonite = 55 t
- Water = 40,320 litres
was 135 t
Electricity increases as machinery requires electricity as an input
Products
- Moulds and cores = 672 tonnes
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

21. Profitability analysis: Mechanical sand reclamation/mixing
Midland Metals CASE STUDY
INVESTMENT COST
Vs.
SAVINGS (annual)
$17,833
31.25% saving on labor
$3,543
24% saving on raw materials
$8,351
Lower overall operating costs*
$2,630
*even with increase in electricity costs
ANALYSIS
Total net savings (per year)
$14,525
Payback Period
<2 years
Net Present Value 5 years)
$25,606
Internal Rate of Return
77%
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit

22. Benefits of Cleaner Production
Midland Metals CASE STUDY
Benefits of Cleaner Production
Improved Profitability
Raw material saving of 25%
Labour costs cut by 30%
Reduced plant and equipment maintenance costs
Improved product quality
5 to 7 fold increase in production levels (pieces/per day), so total profits increase 5 to 7 fold as well
Reduced environmental impact
Improving MSME Performance through Cleaner Production. Module 3: A Closer Look at CP. Visit