Skim Milk Powder Production: A Profitable Dairy Industry
Skim Milk Powder (SMP) is one of the most essential products in the dairy sector, produced by removing fat and water from liquid milk. Due to its long shelf life, preserved nutritional value, and wide application in food industries, SMP holds a significant position in the global market.
This article presents a comprehensive process model for industrial SMP and cream production using SuperPro Designer. It covers technical stages, equipment specifications, economic analysis, and profitability metrics for a plant processing 100 metric tons of milk per day.
Advantages of SMP Production
- Extended shelf life
- Reduced transportation costs
- Preserved nutritional value
- Broad applications in food industries such as cheese, ice cream, chocolate, and bakery
A Brief History of Milk Powder
The concept of drying milk dates back to the 13th century when Mongol warriors used dried milk. The first commercial production was initiated by Russian chemist M. Dirchoff in 1832. In the 19th century, European inventors like Nicolas Appert developed methods for milk concentration and drying, laying the foundation for modern milk powder production.
International Definition of Milk Powder
According to Codex standards, milk powder is a product obtained by removing water from milk. Its composition may be adjusted by adding or removing milk components, provided the whey protein to casein ratio remains unchanged. Only milk and cream are permitted as raw materials.
Milk Powder Composition Table
| Type | Milk Fat | Protein in Non-Fat Solids | Max Moisture |
|---|---|---|---|
| Whole Milk Powder | 26% to 42% | Min 34% | 5% |
| Semi-Skimmed Milk Powder | 1.5% to 26% | Min 34% | 5% |
| Skim Milk Powder | Max 1.5% | Min 34% | 5% |
In the following sections, we’ll explore the detailed production process, equipment, material requirements, cost analysis, and profitability of SMP manufacturing.
Technical Stages of SMP Production
1. Pasteurization
The primary goal of pasteurization is to eliminate pathogenic microorganisms and prepare the milk for further processing. Each batch begins with 100 metric tons of whole milk. The pasteurization sequence includes:
- De-aeration in unit DA-101
- Initial filtration in unit DE-101 to remove impurities
- Cooling to 4°C via heat exchanger HX-101
- Gradual heating to 72°C in pasteurizer PZ-101
- Final cooling to 10°C using chilled water
The pasteurized milk is stored in tank V-103 before moving to the next stage.
2. Standardization
This stage removes fat from the milk to produce skim milk. The pasteurized milk is sent to disk-stack centrifuge DS-101, which separates the cream—yielding approximately 10.62 MT of cream per batch. The cream is stored in tank MT-102 and sold as a by-product.
The skim milk is collected in tank MT-103 and preheated to 45°C using hot water in heat exchanger HX-103, preparing it for evaporation.
3. Evaporation
Evaporation concentrates the skim milk before drying. The preheated skim milk enters flash unit V-101 and is heated to 74°C, causing partial water evaporation. The liquid stream then passes through HX-104, reaching 85°C, and enters flash unit V-102, which operates adiabatically under partial vacuum (0.3 bar, ~70°C).
Vapors from both flash units are combined in mixer MX-102 and condensed in HX-102 using cooling water. The condensate is reused for cleaning and steam generation.
Evaporation Equipment Specifications
| Equipment | Feature | Cost (USD) |
|---|---|---|
| EV-101 | Multi-effect evaporator, 44.46 m² heat transfer area | 724,000 |
| V-101 | Flash drum, 4,668.90 L volume | 18,000 |
| V-102 | Flash drum, 4,543.49 L volume | 18,000 |
After evaporation, the concentrated skim milk is stored in tank MT-104 and prepared for the final drying stage.
Final Stage: Drying and Production Scheduling
4. Drying Process
After evaporation, the concentrated skim milk enters the spray dryer (SDR-101), where approximately 96% of the remaining water is removed. This results in the formation of raw skim milk powder.
The powder is transferred to the vibrating screen unit (VSCR-101) to separate coarse particles. These particles are ground in the grinder (GR-101) and recombined with the main powder stream. The final product is stored in silo SL-101.
Characteristics of the Final Powder
- Color: Pale yellow or creamy white, free of burnt particles
- Texture: Light, powdery, similar to corn flour
- Taste: Mild and similar to fresh skim milk
- Low bulk density with high dispersibility and wettability
Drying Equipment Specifications
| Equipment | Capacity | Cost (USD) |
|---|---|---|
| SDR-101 (Spray Dryer) | 14.77 m³ | 223,000 |
| VSCR-101 (Vibrating Screen) | 1,506.84 kg/h | 14,000 |
| GR-101 (Grinder) | 0.15 kg/h | 83,000 |
5. Production Scheduling and Equipment Occupancy
The SMP production process is designed as a batch operation, with each batch completed in 24 hours. Assuming the plant operates 11 months per year, a total of 330 batches are processed annually.
The Equipment Occupancy Chart (EOC) shows that the most utilized equipment is blending tank MT-103 during standardization, with 13.33 hours per batch. The second most occupied unit is MT-101 during pasteurization, with 12.94 hours per batch.
The Operations Gantt Chart provides a detailed view of each batch’s timeline. Dark blue bars represent procedure durations, while cyan bars indicate individual operations. Users can double-click any bar to edit parameters and refresh the simulation.
This scheduling system helps optimize production capacity, reduce downtime, and improve overall efficiency.
Material Requirements and Cost Analysis
Annual Consumption of Raw Materials
To produce approximately 3,000 metric tons of skim milk powder (SMP) annually, the process consumes various raw materials including fluid milk, phosphoric acid, sodium hydroxide, water, and air. The table below summarizes the annual usage, batch-wise consumption, and per-ton SMP ratios:
| Material | MT/year | MT/batch | MT/MT SMP |
|---|---|---|---|
| Air | 61,493 | 186.342 | 20.611 |
| Fluid Milk | 33,000 | 100.000 | 11.061 |
| Phosphoric Acid 2% | 5,125 | 15.531 | 1.718 |
| Sodium Hydroxide 2% | 5,366 | 16.260 | 1.798 |
| Water | 26,009 | 78.816 | 8.718 |
Raw Material Cost Breakdown
Raw materials account for approximately 65% of the total operating expenditures. The cost of fluid milk dominates the budget, while cleaning agents like phosphoric acid and sodium hydroxide contribute marginally. Water is considered cost-free due to internal condensate reuse. The table below outlines the annual cost distribution:
| Material | Unit Cost (USD) | Annual Amount | Annual Cost (USD) | % of Total |
|---|---|---|---|---|
| Fluid Milk | 0.57/kg | 33,000,000 kg | 18,810,000 | 99.31% |
| Phosphoric Acid 2% | 15/MT | 5,125 MT | 76,879 | 0.41% |
| Sodium Hydroxide 2% | 10/MT | 5,366 MT | 53,657 | 0.28% |
| Water | 0 | 26,009,169 kg | 0 | 0.00% |
As shown, fluid milk is the dominant cost driver, highlighting the importance of stable and cost-effective milk sourcing for project viability.
Labor, Utilities, and Annual Operating Costs
Utility Expenses
Energy and utility services play a vital role in maintaining efficient operations. These include electricity, steam (high and low pressure), cooling water, chilled water, hot water, and calcium chloride brine. The table below outlines the annual consumption and cost breakdown:
| Utility | Unit Cost (USD) | Annual Amount | Annual Cost (USD) | % of Total |
|---|---|---|---|---|
| Electricity | 0.20/kWh | 621,513 kWh | 124,303 | 20.42% |
| High-Pressure Steam | 35/MT | 5,709 MT | 199,824 | 32.82% |
| Cooling Water | 0.10/MT | 1,166,954 MT | 116,695 | 19.17% |
| Chilled Water | 0.40/MT | 35,084 MT | 14,034 | 2.30% |
| CaCl₂ Brine | 0.40/MT | 80,991 MT | 32,397 | 5.32% |
| Low-Pressure Steam | 25/MT | 4,289 MT | 107,218 | 17.61% |
| Hot Water | 0.05/MT | 287,511 MT | 14,376 | 2.36% |
Labor Costs
Labor expenses are based on operator wages. The hourly rate is set at $42, with a total of 50,564 hours annually. This results in an annual labor cost of $2,123,675, accounting for 7% of total operating costs.
Total Operating Cost Summary
Combining raw materials, utilities, labor, maintenance, depreciation, and waste treatment, the total annual operating cost is approximately $29.2 million. The breakdown is as follows:
- Raw Materials: 65%
- Facility-Dependent Costs: 23%
- Labor: 7%
- Utilities: 2%
- Waste Treatment: 1%
Capital Investment and Profitability Analysis
Initial Investment Breakdown
To establish a plant capable of processing 100 MT of milk per day and producing 3,000 MT/year of SMP and 3,500 MT/year of cream, a substantial capital investment is required. The table below outlines the major components of the investment:
| Investment Item | Cost (USD) |
|---|---|
| Direct Fixed Capital | 50,625,000 |
| Working Capital | 1,112,000 |
| Startup Cost | 1,908,000 |
| Up-Front R&D | 0 |
| Up-Front Royalties | 0 |
| Total Investment | 53,645,000 |
Annual Revenue Projections
Based on assumed selling prices of $4,500/MT for SMP and $7,600/MT for cream, the plant generates the following annual revenues:
| Product | Annual Volume (MT) | Unit Price (USD/MT) | Annual Revenue (USD) |
|---|---|---|---|
| Skim Milk Powder (SMP) | 2,983 | 4,500 | 13,424,603 |
| Cream | 3,504 | 7,600 | 26,629,595 |
| Total Revenue | 40,054,198 | ||
Profitability Metrics
- Annual Operating Cost: $29,163,000
- Gross Profit: $10,893,000
- Taxes (28%): $3,050,000
- Net Profit (incl. depreciation): $12,652,000
- Gross Margin: 27.2%
- Return on Investment (ROI): 23.6%
- Payback Period: 4.2 years
These metrics confirm that the SMP and cream production project is financially viable and represents an attractive investment opportunity in the dairy sector.
Equipment Specifications and Purchase Costs
The SMP production facility relies on a range of specialized equipment to execute each stage of the process efficiently. These include evaporators, blending tanks, filters, dryers, centrifuges, heat exchangers, and more. The table below summarizes the main equipment, their descriptions, and purchase costs (2022 prices):
| Equipment | Description | Unit Cost (USD) |
|---|---|---|
| EV-101 | Multi-effect evaporator, 44.46 m² heat transfer area | 724,000 |
| MT-101 | Blending tank, 111,243 L volume | 449,000 |
| MT-103 | Blending tank, 99,174 L volume | 424,000 |
| DE-101 | Dead-end filter, 90 m² filter area | 329,000 |
| SDR-101 | Spray dryer, 14.77 m³ volume | 223,000 |
| MT-104 | Blending tank, 20,011 L volume | 200,000 |
| DE-102 | Dead-end filter, 50 m² filter area | 188,000 |
| PZ-101 | Pasteurizer, 12,515 L/h throughput | 186,000 |
| DS-101 | Disk-stack centrifuge, 12,540 L/h throughput | 125,000 |
| SL-101 | Silo, 11,818 L volume | 80,000 |
| HX-101 to HX-106 | Heat exchangers and condensers, 2.21–110.8 m² area | 13,000–78,000 |
| Unlisted Equipment | Miscellaneous units and accessories | 2,786,000 |
Total Equipment Cost
The total purchase cost for all equipment is approximately $6.49 million. These units are essential for maintaining process integrity, product quality, and operational efficiency throughout the plant.
Conclusion: A Profitable Model for Dairy Processing
This comprehensive analysis of skim milk powder (SMP) and cream production using SuperPro Designer demonstrates the technical and economic feasibility of the project. From pasteurization and standardization to drying and packaging, each stage is optimized for efficiency and quality.
With a capital investment of approximately $53.6 million and annual operating costs of $29.2 million, the plant generates $40 million in annual revenue. The project yields a gross margin of 27.2%, a return on investment of 23.6%, and a payback period of 4.2 years.
SMP is a high-value product with long shelf life and wide applications in food industries. This model offers a scalable and profitable solution for dairy manufacturers seeking to expand their product portfolio and optimize resource utilization.
Source
For full technical documentation and simulation details, refer to the original publication:
ResearchGate – Skim Milk Powder Production by Amaury Perez Sánchez et al.
