FAQ’s Batch Mixing Systems & Blending

The batch mixing process is one of the two main methods of product mixing. The other is continuous mixing. Batch mixing is a process that produces products in batches: all ingredients are added into a batch and mixed or blended together at once. After each batch is done mixing, the product is discharged all at once and the process starts over. This is different from continuous mixing where product is constantly flowing through the system.

Automatic batch blending or mixing is preferred mode of mixing for many industries and applications producing small to medium capacities or products that are not compatible with continuous mixing because of reaction times, long processing steps, or other factors. A batch mixing process typically consists of three sequential steps:

• Weighing and loading mix components
• Mixing
• Discharging the mixed product

The mixture is typically a combo of dissimilar materials. In other cases, chemically homogenous material may be mixed using this chemical mixing system to produce a uniform lot of a desired weight or volume with consistent particle size distribution, color, texture, and other required attributes.

Mixing and blending are often used as synonyms but are subtly different. Mixing is a more vigorous process that results in a homogeneous mixture where particles are evenly distributed throughout. Blending is a more gentle process with less uniform dispersion – think of a hand-mixed cake batter with lumps (blending) vs. a smooth, mechanically mixed batter (mixing).

In terms of the phase of material, blending is the process of solid-solid mixing or mixing of bulk solids with a small quantity of liquid. Mixing is generally used more with liquid-liquid, gas-liquid and viscous materials.

Blending can be run multiple times within a manufacturing process when new ingredients need to be added to the blend. It can be used to combine fillers, binders, lubricants or disintegrates, to name a few.

The critical process parameters include blend speed and time. To ensure a homogeneous mixture from a blending process the incorporation of process automation to monitor blend uniformity may be required to prevent excessive blending. Excessive blending can lead to electrostatic build-up, attrition and over lubrication.

Batch mixing systems are process systems that make product in batches, usually in large tanks. Ingredients are added all at once or in an automated sequence and blended together to create a batch of product. Product is discharged and the process starts over.

This is different than a continuous mixing system, a common example of which is an inline blending system. In continuous mixing, product is continuously produced. Inline systems usually have a base flowing through pipes – such as water – to which other ingredients like scents, dyes, and flavors are added and mixed while product flows through the piping.

Batch mixing systems are more versatile than continuous systems, but continuous systems can be more economical. Less equipment is required for continuous, and more product produced in the same time period. Products with long mixing times, vastly different viscosities, reactions, or solubility issues will almost always be difficult to do in a continuous mixing system.

In short, no. Automation can add a lot of efficiencies to your process, but we build custom mixing systems that range from nearly—manual to fully automatic batch blending. There are advantages and drawbacks to each blending approach:

Manual batch blending is the most flexible option and has the lowest capital cost. It is possible to make a wide array of mixtures and conduct a large number of reactions in the same tank using this approach. The main downsides are that manual batch blending is relatively slow and labor-intensive. Additionally, because operators weigh the raw materials, human error and variability are factors.

Fully automatic batch blending or mixing systems are designed to reduce human error and variability. While an automated approach also means an increase in capital cost (added instrumentation, automated valves, programming and required bulk storage), cycle times are significantly reduced along with manpower requirements. Increases in throughput and reduced operating expenses are typical with automated blending.

Typical in-line blending systems include base/pre-mix dosing, major and/or minor ingredient dosing and finished product delivery. These fully assembled and tested systems can be used to create a wide range of finished products.

Semi-automated batching systems offer an in-between option. When designing semi-automated systems, we look for the areas where investing in automation will give you the most return for the investment. Worker safety and total line speed flow are also major factors in designing semi-automated batch systems.

The cost of a batch process manufacturing system varies tremendously and depends on several key factors, including:

• Application complexity — more complex = higher costs
• Process conditions — High temperatures and high pressures also drive price up. The more difficult or unusual the process conditions, the higher cost will be.
• Hygienic design – documentation, validation, and extra precautions for proper slope, drainability and cleanability will add costs to your mixing system.
• Flammables – Flammability changes relief sizing and electrical classification which, in turn, effects instrumentation and materials of construction costs.
• Instrumentation — Depending on what you are doing with your process system – i.e. is it an experimental pilot plant or a permanent production skid? – Varying levels of instrumentation may be needed.
• Flow Rate — The higher the flow rate, the larger the required piping, vessels and instrumentation sizes. Larger piping and instrumentation cost more (e.g. a 4-inch diameter pipe costs dramatically more than a 1/2 inch pipe).
• Number of pieces of equipment — more equipment = higher costs
• Materials of Construction — do you need premium materials? Exotic materials cost more.
• Existing on-site utilities — if you have fewer utilities already available, that will drive up your price
• Overall site readiness — Is there an existing concrete pad with electrical hookups and utilities? If not, concrete and civil work should be taken into account.
• Specialty craft labor — the more specialized work you need, the more your costs will grow
• Procurement accuracy — Poor procurement specifications can put you behind schedule, bumping your costs higher
• Operating costs — these include everything needed to run the plant on location. Raw materials, electricity, water and man-power are all examples of typical operating costs.

For a quote on a custom batch mixing system, please contact EPIC 314-714-1580.

A custom mixing systems at EPIC are developed in seven steps through our design/build process, which includes:

1. Concept Development – The first stage of any project is the concept stage, provided by the client. You might start with a drawing or basic spec sheet or bring fully developed P&ID’s. Whatever stage you are at, we thoroughly review your concept and begin working on basic design.
2. Front-End Engineering Design – Front End Engineering Design (FEED) is a basic design effort with the goal of providing accurate pricing and project timelines. It is typically completed over the course of several weeks and comes with a fixed quote bid.
3. Process System Design – The design work that started in front-end engineering is finished during the design stage. Your engineer develops a custom modular process system for your proprietary, base process technology.

Process system design incorporates:

• Detailed process design
• Mechanical design
• Structural design
• Hardware specification

4. Process Controls Engineering – Process controls work begins concurrently during the design of your system. This covers the design of:

• Programming Platforms:
  -Logic Programming
  -PLC Programming
  -PC-Based Programming
  -DCS Programming
  -Operator Interface and HMI programming
• Process data collection
• Process simulation
• Process Instrumentation

5. Modular Fabrication & Assembly – Your batch mixing modules are built at EPIC in our state-of-the-art fabrication plant. Any on-site modifications to your plant are made in parallel, and modules are fully tested before leaving our facility to be installed at your plant.
6. Process System Installation – Engineers fully integrate and install your new modular batching system into your manufacturing facility. This may include plant integration, construction management and control system programming. Factory Acceptance Testing) should be completed before shipment.
7. Start-up & Commissioning – This includes punch list resolution as well as operator and maintenance training provided by your process consultants. Continuing project support should be to your team after project completion for troubleshooting any issues.

Learn more about mixing services here, or contact an engineer (314)-845-0077 to discuss your specific application