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Sand Reclamation Basics

Simple Solutions That Work!,  Volume 12, April 2020 
Written - Jack Palmer

Jack Palmer
President
Palmer Manufacturing & Supply, Inc.

Article Takeaways:

  1. Understanding the importance of reclamation
  2. Reducing costs with reclamation
  3. Environmental impact

WHAT IS SAND RECLAMATION?

Sand Reclamation is the physical, chemical, or thermal treatment of used foundry casting sands so that they can safely and effectively be re-used for molding and coremaking applications.

WHY BOTHER WITH SAND RECLAMATION?

Acquisition Costs

For many years, sand was cheap and readily available for foundry applications. Over time, we have seen the costs of sand grow due to increased mining costs, increased transportation costs, increased Quality Assurance costs, Alternative Higher Profit Applications (such as Frac Sand), etc.

Sand reclamation will allow re-use of sand, which reduces the amount of new virgin sand which must be sourced in order to maintain production.

Disposal Costs

For many years, most cities, counties, and even many foundries had their own landfills where spent sand could be disposed of. Over time, there have been many changes in regards to safety regulations, health codes, etc that have greatly reduced the number of disposal facilities and increased the disposal regulations. With this comes a much higher cost for disposal.

Sand reclamation will allow re-use of sand, which reduces the amount of used sand which must be disposed of.

Environmental Responsibility

Less new sand usage helps to maintain Earth’s resources. More sand re-use reduces waste.

It’s just the right thing to do, both financially and environmentally.

Silica Exposure Limits and Synthetic Sands

With the current silica rules and the inability of some foundries to meet the exposure limits, one of the solutions pursued by some is to completely remove silica from their facility and switch over to a synthetic sand. With costs of synthetic sand being in the range of 10+ times higher than standard silica sand, it will make reclamation significantly more important in order to remain profitable with increased material costs.

SAND RECLAMATION SYSTEMS

There are 2 major types of sand reclamation systems:

A mechanical reclamation system uses motion energy to physically break down chunks of spent casting sand into a clean, usable, grain size sand.

A thermal reclamation system takes sand that has been broken down to grain size in a mechanical reclamation system and adds heat energy in order to burn the remaining resins off the sand.

In most cases, a mechanical reclamation system is a requirement before a thermal reclamation system can be added. Historically, most foundries go through the evolution of:

There are a smaller percentage of foundries who will add an entire new molding line and will include new mechanical and thermal reclamation systems from the start.

Mechanical Reclamation System

A typical mechanical reclamation system will include the following sequence of components:

Thermal Reclamation System

A typical thermal reclamation system will include the following sequence of components:

If a Thermal Reclamation System is being included, there are different schools of thought by foundries as to sizing and usage. Some foundries will thermally reclaim all sand. Others will only thermally reclaim a portion of their sand and will then blend it into the system in order to control their LOI readings. This choice will also affect the total lists of equipment components to included in a typical system, and will affect exactly where the sand stream exits the mechanical reclaimer and enters the thermal reclaimer

Benefits of Thermally Reclaiming ALL Sand:

Disadvantages:

Benefits of Thermally Reclaiming only a portion of Mechanically Reclaimed Sand:

Disadvantages:

Thermal Reclamation System Types

Mechanical Reclamation System Offerings

A basic mechanical system includes:

A basic mechanical reclamation system is a good choice for foundries who:

Shakeout Deck Attrition Mill Combination units are available in deck sizes of 3’, 4’, 5’, 6’, and 7’ square. Generally, the maximum mold should be at least 1’ smaller than the size of the deck.

Optional Upgrades to basic mechanical systems:

After the classifier, the sand will generally need directed to a different silo for bulk storage, or back to a daytank for point of use storage. In either case, as there is generally horizontal distance between the classifier and this storage location, a pneumatic transporter is an excellent way to move the sand to its destination.

There are times when a foundry may need a system that has more capability than a basic system. Some examples may be:

In these cases, it is very common to change from a shakeout deck/ attrition mill combination unit over to a system that has separate pieces of equipment for shakeout and attrition, as well as often having vibratory lift devices to elevate chunks of sand.

As always, it is best to work with your supplier giving a full scope of the reclamation work that needs to be done, including both the odd size pieces, as well as the bulk sizes that cover 90% of your production. With this information, a system can be designed that will meet the environmental desires, the simplicity of use, and the financial savings that help to make sand reclamation the right choice.