Industrial mixers

Conical vacuum mixer dryer

Mixes and dries in the same vessel, under vacuum, products that will not survive the temperature of a conventional dryer — pharmaceutical intermediates, pigments, advanced materials, food ingredients. Built routinely between approx. 500 and 30,000 L, in AISI 304 or 316L stainless.

Usual configurable range: approx. 500 – 30,000 L
Usual installed power: approx. 7.5 – 160 kW

Also known as: conical vacuum dryer · nauta dryer · conical screw mixer dryer · vertical conical dryer

approx. 500 – 30,000 LAISI 304 / 316L stainless

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Individually sized on your material and your process. Technical proposal and price normally within 48 hours. Delivery across the EU and the Republic of Moldova.

How it works

This machine solves a temperature problem. A heat-sensitive product degrades if you dry it at atmospheric pressure, because the solvent only boils at its normal boiling point. Under vacuum, that same boiling happens tens of degrees lower, so the moisture leaves the material without the material suffering for it.

Mixing is done by a helical screw arm that rotates slowly about its own axis while orbiting along the conical wall. Material is lifted along the wall and falls back through the centre. The motion is gentle: crystals and granules are not broken, and specific energy consumption stays low even at large volumes — which is why this design is chosen for products whose final particle size is part of the specification.

A jacket on the conical body heats or cools the batch, while vapour is held back by the filter in the lid and passes into a condenser, where the solvent is recovered instead of being vented. The conical bottom empties completely by gravity — no residual heel to scrape out by hand and find again in the next batch.

Drying at low temperature

Vacuum lowers the boiling point of the solvent, so the product dries without thermal degradation.

Mixing without breakage

Slow-turning helical screw arm: crystals and granules keep their particle size.

Solvent recovered

Lid filter and optional condenser — the solvent is collected instead of vented.

Complete gravity discharge

The conical bottom leaves no heel between batches, so no cross-contamination builds up.

When to choose it

The concrete situations in which this machine is the right answer — and the one in which we would point you to something else in our range.

The product is heat-sensitive and degrades at atmospheric drying temperature — under vacuum the same moisture leaves tens of degrees lower.

The solvent in the batch has to be recovered rather than vented: either because it is expensive, or because it must not reach the atmosphere.

Final particle size is part of the specification and mixing must not break the crystals.

Mixing and drying have to happen in the same vessel, with no intermediate transfer — every transfer means product loss, exposure and one more cleaning operation.

When this is NOT the right machine

If the product is a dry powder that only needs homogenising, with no drying and no vacuum, a conical dryer is a far more expensive machine than you need.

See Ribbon blender

Line of stainless steel reactors and process vessels built by Altebo in its own production hall

Specifications

The ranges we build routinely. Final dimensions and installed power follow from the density and viscosity of the product, the batch size and the process conditions.

Technical specifications — Conical vacuum mixer dryer
Configurable volume	approx. 500 – 30,000 L
Product contact material	AISI 304 / 316L stainless
Mixing system	Slow-turning helical screw arm with orbital motion
Jacket	Heating and cooling, on the conical body
Operating regime	Under vacuum
Installed power	approx. 7.5 – 160 kW, depending on product and volume
Working vacuum	Typically below 100 mbar absolute; the exact level is set from the solvent to be evaporated
Operating temperature	Jacket for hot water, steam or thermal oil — typically up to approx. 200 °C, depending on the heating medium selected
Options	Condenser and solvent recovery · CIP system · load cells · instrumentation and PLC automation

The figures above are the ranges we build routinely, not construction limits. We design and manufacture any capacity, power rating and envelope to order — including below or above the ranges in the table.

Build variants

What actually changes between them — not just what they are called.

Single screw arm

The standard version. One arm travels the conical wall — enough for most free-flowing powders and granulates.

Twin screw arms

Chosen at large volumes and for poorly flowing materials: the second arm shortens homogenising time and reduces the zones where material stagnates against the wall.

With a de-agglomerating chopper

A separate high-speed element that breaks up the lumps formed during drying. Needed when the product cakes as it loses solvent.

Sanitary execution

Internal surfaces polished to Ra ≤ 0.8 μm, joints without retention pockets and a CIP system — for pharmaceutical products and food ingredients.

Where it is used

The industries we build this machine for — each with its own execution requirements.

Mixing technology

Vacuum mixing and drying

Frequently asked questions

Question not answered here? Write to us — an engineer replies, not a bot.

How long does drying a batch take?

It depends on the quantity of solvent, the jacket temperature and the vacuum level — there is no figure valid for every product. Send us the solvent, the starting and target moisture, and the maximum temperature the product tolerates, and we will calculate the heat transfer area required and the resulting cycle time.

What happens to the evaporated solvent?

It passes through the lid filter, which stops entrained powder, then into a condenser, where it becomes liquid again and is collected. Without a condenser the solvent would end up in the vacuum pump and in the atmosphere; with it, the solvent is recovered and can be reused.

Why a conical bottom and not a flat one?

Discharge. A conical bottom empties the batch by gravity, completely, without leaving a layer of product behind. A flat-bottomed vessel always retains a heel that has to be removed by hand — product lost on every batch, and a cross-contamination risk between recipes.

Can it be cleaned without dismantling?

Yes, with a CIP system: spray nozzles in the lid covering the conical wall and the mixing element. It is designed in from the start, because nozzle positions follow from the geometry of the arm. Tell us how often you change product — that decides whether CIP is justified.

How does it differ from the vertical vacuum mixer dryer?

The conical one mixes with an orbiting helical arm, gently, and empties completely by gravity — suited to crystals and to products where particle size matters. The vertical one uses a ribbon or helical element on a central shaft, with more energetic circulation, suited when the product also has to be homogenised intensively, not only dried.