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A large step cone, GJL. Casting temperature: 1410-1420 °C. Water-based coating, approximately 300-µm layer thickness.
  1. Ask the Expert

A Sustainable, Cost-Effective Option for Sand Additives

March 6, 2023
A lithium-free sand additive will help foundries achieve process goals while avoiding the liability of material dependence in a market focused on e-mobility.

Q: Our foundry’s costs for sand additives continue to rise. How can we keep these costs under control and still achieve good molding performance and a stable supply?

A:  Constantly rising demands for productivity and efficiency are always present for metalcasting operations. At the same time, social goals and political requirements are changing the choices available to foundries for achieving productivity and efficiency. Specifically, communities and governments want to move away from established, combustion engine technologies in favor of electric powertrain systems, with near-term targets for the switch.

In the course of this transition, one raw material is gaining enormous importance: lithium.

Lithium is a key component for the rechargeable battery technologies that EV manufacturers are adopting, but it is also an essential component of sand additives.

The lithium supply situation – and especially the development of the materials’ cost – are hard to predict. Against this background, ASK Chemicals has set itself the goal to develop novel, lithium-free sand additives called VEINO ULTRA, which match the demands of foundries for sustainable and cost-effective sand preparation. In close cooperation with many foundries, considerable success has been achieved over the last several years. With these innovative sand additives from ASK Chemicals, foundries can continue to meet the current and emerging requirements.

The increasing importance of electromobility is prompting extremely high demand for lithium for battery production. The resulting shortage of this raw material is forcing the foundry industry and its suppliers to fundamentally reorient themselves. Thanks to the development of a new generation of innovative lithium-free sand additives, which are in no way inferior to conventional lithium-containing ones, the total amount of lithium required for the production of additives at ASK Chemicals has been reduced by 100%.

After extensive screening of alternative raw materials, ASK Chemicals’ Research & Development team arrived at a lithium-free solution. The first trials done in our foundry pilot plant (see Figure 1) were successful, and as a result the new product was further tested in field trials at a customer's site.
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Fig. 1: Coated dome cores; additive addition 2% in the sand mixture, casting in cast gray iron, casting temperature approximately 1420 °C.
Fig. 1: Coated dome cores; additive addition 2% in the sand mixture, casting in cast gray iron, casting temperature approximately 1420 °C.

The newly developed sand additives have proven their worth in several respects:
-  Significantly reduced casting defects that lead to rework or rejects;
-  Reduction or even elimination of specialty sand additions;
-  Under certain conditions, coating-free casting becomes possible;
-  Reductions in overall additive usage rates with similar performance; and,
-  Very good flowability of the core molding material with good contour reproduction.

Special sands are natural mineral sands, sintered and melted products that are produced in granular form. They differ from silica sand in particular in their significantly lower thermal expansion behavior in the temperature range from 20° to 800°C. In the casting process, special sands such as chromite sand, ceramic hollow spheres, andalusites, and feldspar sands are used. The quantities added (usually 30-100%) vary greatly depending on the specific requirements.
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Fig. 2: Material cost comparison (base: quartz sand.)
Fig. 2: Material cost comparison (base: quartz sand.)
Alternatively, with a few exceptions, they are not reclaimable/separable and they generate high disposal costs. Above a certain level of accumulation, the use of special sands also may negatively impact the green sand system. Plus the cost of special sands can fluctuate widely. Unfortunately, in many cases those costs are accepted (see Figure 2), because no alternative is available to achieve the desired quality. The following example shows that it is possible to replace chromite sand without sacrificing casting quality (see Figure 3.)
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Fig. 3: A large step cone, GJL. Casting temperature: 1410-1420 °C. Water-based coating, approximately 300-µm layer thickness.
Fig. 3: A large step cone, GJL. Casting temperature: 1410-1420 °C. Water-based coating, approximately 300-µm layer thickness.

The development of powertrain technology in the automotive sector as it adopts e-mobility systems makes it very clear how important battery production is, but also how dependent those manufacturers are on lithium as a raw material. Supply bottlenecks and significant price increases have been seen.

Because lithium also has been an essential component in many sand additives for more than 30 years, a technical alternative has been developed by ASK Chemicals that can help your foundry “Be Ahead” of the curve when it comes to overall profitability.

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