"On those stepping into rivers the same, other and other waters flow." This perception of HERAKLIT de-scribes intuitively the working princi-ple of a mixing plant in continuous operation. All ingoing raw materials named further on phases are flowing in one direction through the machine. On their way they are passing particular mixing chambers, where they are being unified with each other. Simul-taneously energy from the outside is applied in order to intensify the ho-mogenisation. The input of energy is provided in a limited and controlled space inside the specially designed chambers. Finally on at the exit of the plant finished product in the de-sired quality emerges ready to be taken for filling and packaging. At each line and at every point all phases in the plant are treated al-ways in the same manner, whereas according to HERAKLIT they will never return. The method of this particular contin-uous mixing is a smooth and straightforward approach of proces-sing without breaks and backflows. It has s two big advantages: To ob-tain constantly top product-quality and also in the same time saving a lot of costs. Therefore the continu-ous mixing belongs to the most ef-fective production types in the in-dustry.

Batch versus Conti-plant Up to now the manufacturing of e-mulsions and dispersions takes pla-ce mainly in Batch – mixing equip-ment. Each individual charge is wor-ked out in one tank. In most case big voluminous stainless steal ves-sels are used able to work under pressure or vacuum. In these ves-sels the product is mixed and homo-genized from the beginning to the end. During these operations the vessels normally are heated up and later cooled down after the final ho-

mogenisation step. As products are obtained various types of skin-care forms like creams, ointments, lo-tions, sun-care protection or gels, well known under the typical brand names in the market. Typically for Batch-production are the low grade of automatisation, long production pauses for exten-sive cleaning and another inherent lack of the processing method: big variations in the out coming quality with broad ranges of the distribu-tions. The directly or indirectly influ-enced costs by this method are enormous. [1], [2] Mixing in each step always in

the same way In the HEBOLD contiline system the treatment of all phases is carried out in fixed sequential steps. Similar types or raw material are grouped together to only one phase. They run through the plant and are unified

up to the final output as ready pro-duct. With even throughputs implemented for each line and with all phases in the same properties stable condi-tions in the mixing zones are re-mained constantly. After restart of the mixer the stationary estate is easily again established. With this operation mode every volume-ele-ment of the product is treated even-ly. Finally the outcoming of the con-tiline are very fine products with small particle sizes and moreover very narrow distributions leading to highly stable emulsions for longer shelf lives. Directly into the filling without

intermediate stockage

The Conti-Mixing-plant does not need much space for the installa-tion. Even when highest throughputs

Continuous HEBOLD Mixing technology

[1] C.Ehwers, S. Küppers, Nachr. Chem 2002, 50,1255 [2] Handelsblatt 06/2000, HSBC 03/2000

Hebold Mixing and More GmbH Grodener Chaussee 25-29 D 27 472 Cuxhaven Tel.: + 49 ( 0 ) 4721 60 18 0

Fax: + 49 ( 0 ) 4721 60 18 50 sales@hebold-cuxhaven.de www.hebold.net

* According to individual viscosities the total throughput can vary. After checking the pro-

duct and all the materials in the HEBOLD laboratory more precise rates can be nominated

Type : Throughput Power Dimension Weight

app. [l/h] product* [kW] [mm] [kg]

von bis ( Mixing power ) A B C

NM 25 6 20 0,7 1200 750 1750 370

NM 50 50 150 1,5 1600 800 1950 600

NM 72 150 400 3 1800 800 1950 650

NM 100 400 1250 6 2000 800 1950 720

NM 120 700 2000 10 2000 800 1950 720

NM 200 3000 7000 45 2000 1000 1950 850

Other sizes upon request

Types Sizes – other technical features

Pic. 1 nanoCONTI-unit NM 50: Two high grade mixing chambers switched in line,

feeding in each chamber possible, adiabatic manufacturing gy means of a heatable oven,

cooling post, Coriolis mass-flow counters

A great advantage of the phase splitting is that in many cases a subsequent cooling of the product is not any more necessary. Because here the big part of the external phase in most cases water is given to the plant cold or under room temperature. A further important function of the operati-on is the duration of how long the product will stay in the mixing chamber ( “ R esidence-Time ” ) . The user can decide to leave the product longer ore shorter in the chambers means applying shorter shearing treatments or extend the acting shear force for a longer period. Particularly for systems with longer acting emulsifiers the system is advantageous: Up to 40 seconds for one stay of the prod-uct in the mixing chamber is easily adjust-able. Active agents and emulsifiers are en-forced to act more efficient. High resi-dence times in the chambers permit to build up these favourable conditions and the formation of fines droplets and micro structured systems. On the other hand Rotor-Stator units or high-pressure homogenizers keep the product for much less time in the working zone. Their residence times are often mi-nor than a second and unfortunately this diminishes also when these units are go-

ing up with their speed or pressures. Once the product escapes of the shear zone the inserted energy could lead to negative effects: A destabilisation of the system and a re-agglomeration of the fine parti-cles to bigger scales. In such cases the product has to be much longer homoge-nized or the proportion of the emulsifier increases, which also can cause negative effects on the end-quality. In contrast to these systems the continu-ous mixing with the HEBOLD contiline is bringing less energy into the product and achieves similar or even better results than the high shear or high pressure sys-tems. Because of this reasonable deploy-ment of energy with the Conti-technology other negative effects e.g. temperature peaks or big wear of the mixing parts can-not take place. One concept from laboratory to

big industrial scales Are the conditions in a mixing chamber easily and at any time reproducible, so is the case if a recipe has to be transferred from a small Conti-unit to a bigger plant ( S cale-Up ) . Between each dimension of every machine the sizes of geometrical relations in the length, width and height is maintained. Under these conditions it is guarantied that when running different sizes of the machine the energy input into the product also remains the same. A recipe started on a small laboratory unit then is very easy implementable on a production unit. This feature has been tested already with a lot of different products.

The company HEBOLD Mixing & More is presenting the machines in their work-shops and is offering interested customers to test the technology with their product and the according raw material on smaller Conti-units in the own laboratory. Please ask us or our sales department for further information.

Pic. 4: Comparison

particle sizes nanoCONTI / High pressure ho-

mogenizer, O/W Emulsion 15%

Silicon, premix of

cosmetic product

Pic.5: Laboratory unit nanoCONTI-NM 25 for

product development, 5 dosing lines each of them

heat– and coolable, automatic control and process

data recording

Benefits of the HEBOLD contiline :

With minimal energy input to opti-

mal results

Emulsions up to nanoscale range

feasible

Cost savings due to obsolete

cooling

Alternative to High pressure

Homogenizers

Direct Up-Skaling

Direct connection to an automatic

filling line without intermediate

storage

Narrow particle size distribution

for long shelf life

Option pharma conform execu-

tions with CIP– and SIP

Explosion proof executions

operating small quantities the raw material is taken out of prepared containers it is possible to connect big storage tanks and direct water-dosings when making high outputs. For filling systems all different types are attachable. Then product so to say flows straightforward in to the fil-ling unit and further on into the pack-ing line: e.g. in to the filling hopper for tubes, cups, cans or bottles. Intermediate storage containers or emptying devices before going to the filling line are not necessary. And because of that omission further savings are created: Less losses of final product when discharging one time from the batch machine and the second time from the intermediate containers. Moreover time is saved as less cleaning is necessary and this means also less risks for conta-mination and quality reduction. Finest emulsions up to na-

noscalings are feasible

The systems operates with 2 mixing chambers in line each of them using heavy duty stirrers. By means of their special design energy can be transferred to the product as a spe-cial shearing force and to generate very small particles in form of drop-lets in the internal phase. In many cases particle sizes leading down to nanoscales could be obtained. Comparable results achieve High-Pressure Homogenizers. They use high pressures and lead the product to narrow nozzles when the pressure is releasing. In these machines the product is being extremely sheared and submitted to cavitations. Disad-vantageous are that this causes high wear of the material. In addition to that sensible products do not bear such fast reductions of the high pressure. The strategy of the HEBOLD conti-line is basically different. The work-ing pressure is moderate and the flow of the phases through the ma-chine is so even that in many cases a laminar flow occurs.

These conditions could be easily established by the operator. In the by HEBOLD developed con-trol system on one side all single streams of phases are steplessly changeable. And also directly man-ageable is the grade of the whole throughput, keeping the relations between each phases constant to respect the given recipe. The flows are permanently measured and indi-cated on the control panel.

Splitting of phases creates

optimal mixing conditions

In order to obtain very fine particles in the range of sub-microns an other very important step in the processing

is applied in the HEBOLD contiline system: The phase-splitting. Several or only one phase are divid-ed and are fed to the Conti-plant at different mixing chambers in a dis-tinctive relation to each other. This well known method generates spe-cial intermediate estates with con-centration gradients. Together with an external treatment over shear forces very fine particles are ob-tained. The unit enables to steer directly to such conditions and it still allows also to handle them. In a batch plant this special treatment to such an extend is not possible and in equal measure also not feasible in a high pressure homogenizer.

Pic. 2 Principle of the plant: to each mixing chamber several direct inlets of raw

materials are possible, Other units like the cooling stage and dosing devices not shown

Pic. 3 Phase splitting: Sample where only 35% of the total raw mater ial is

processed hot. All other ingrediences are taken at ambient temperature. A further

cooling down of the product is not necessary.