WO2006110024A1

WO2006110024A1 - Salt product, method for manufacture and use thereof

Info

Publication number: WO2006110024A1
Application number: PCT/NL2005/000276
Authority: WO
Inventors: Lambert Hooiveld; David-Jan Janse
Original assignee: R & H Minerals B.V.
Priority date: 2005-04-11
Filing date: 2005-04-11
Publication date: 2006-10-19
Also published as: WO2006110029A1

Abstract

The invention relates to a salt product, method for manufacture and use of such a salt product. Provided is a method for the manufacture of a salt product in the form of a body, comprising providing a composition comprising MgCl2.6H2O and/or CaCl2.2H2O salt hydrate; heating said composition causing the salt hydrate to melt but not to decompose; bringing a volume of said heated composition into a shape; and allowing said volume of heated composition to cool causing the salt hydrate to solidify in said shape. Also provided is a salt body comprising a salt hydrate solidified to a predetermined shape from a state in which the MgCl2.6H2O and/or CaCl2.2H2O salt hydrate is molten. Furthermore, a method is provided of applying a salt to a human skin comprising rubbing the hand-held salt body over the skin causing salt from the hand held salt body to dissolve and to be left on the skin in an, at least initially, dissolved form.

Description

TITLE: Salt product, method for manufacture and use thereof

TECHNICAL FIELD AND BACKGROUND ART

The invention relates to a salt product and to methods of manufacturing and using such a salt product.

After extraction from the sea, a lake or underground deposits, salt will typically consist of crude lumps or granules. The crude salt can be directly ground, packed and marketed or refined before being sold for human and animal use. Salt refineries may re -dissolve the crude salt and evaporate the brine under vacuum to obtain a fine pure recrystallized powder which is dried and packed. Food grade salt is the crystalline product consisting predominantly of sodium chloride (NaCl). It is obtained from the sea, from underground rock salt deposits or from natural brine.

A granular form is advantageous for a rapid dissolution of a salt in water. For certain applications, e.g. as a table salt, salt in a granular or crystalline form is the preferred choice. For other applications however a non- granular salt product that allows for controlled dissolving of the salt is preferred.

Bath salts and salt scrubs are well known examples of cosmetic salt products. When added to the water in a bath tub, bath salts have a relaxing effect and leave the skin feeling soft, refreshed and in some case relieved from itching. Salt scrubs are generally used to exfoliate the top layer of dead skin cells. Typically, bath salts and salt scrubs contain various additives, such as fragrances, essential oils and colorants which, upon dissolution of the salts in water, are rapidly released. The bath salts also aid in opening the skin's pores to allow the essential oils to penetrate the skin. Depending on the type of salt used, bath salts and body scrubs can also have therapeutic properties, e.g. they can relieve skin ailments such as acne, eczema and psoriasis. Particularly well known is the use of natural salt crystals from the Dead Sea. Dead Sea salts are renown for their ability to strengthen the immune system, detoxify, improve circulation, relieve aches and pains, soften and heal the skin, reduce fatigue, release tension, rejuvenate and revitalize. It is believed that the therapeutic properties of the Dead Sea are due in large extent to the presence of these other salts, mainly those of magnesium, potassium and bromide. Whereas in ordinary sea water sodium chloride (common salt) is the major constituent (about 80% of the total salt content) the Dead Sea on the other hand contains a considerably smaller proportion of sodium chloride, the balance consisting of magnesium, potassium and calcium chlorides, and a comparatively high concentration of bromides.

Another common bath salt is Epsom salt, which is made up of hydrated magnesium sulphate. Epsom salt baths are used for combating stress and alleviating muscular aches and pains. The high magnesium content in Epsom salt baths also facilitates the removal of acids through the skin.

Bath salts are provided in the form of crystal-like granular or flaky products. A granular form is advantageous for a rapid dissolution in water. The smaller the salt's granule size is, the faster it dissolves in the bath. The usual and the most common size of bath salt granules is between 2 and 4 mm, although bath salts with a size of 4 -15 mm are also available. The highest quality of salts' granules is considered to be 1-2 mm.

However, because of the rapid dissolution of granular bath salt in water, these salts are inefficient and cumbersome to handle if application of large amounts of salt per unit of skin surface is desired and unsuitable for use under the shower. Following application of salt granules onto the body, the salts easily dissolve in the water emerging from the shower. Moreover, often a substantial proportion of the granules falls down and is rinsed away before having been in contact with the body. When dissolved, the salt will be significantly diluted and rinsed off the body into the drainage. It will be clear that the cosmetic and/or therapeutic effectiveness of granular bath salts when used in the shower is at best very limited.

Salts are also commonly used as feed additives to supply trace mineral supplements to the normal animal diet. Examples of metals of which addition to the diet is sometimes desirable are iron, copper, manganese, cobalt, zinc, and magnesium. Salt supplements in a non-granular form such as a salt lick block are preferred because these are more easily distributed to animals (troughs or other receptacles are not needed). Compared to the granular form, the compacted salt supplement has a better weather resistance and lower wastage. Known animal salt lick blocks (salt licks) are typically produced by compressing sodium chloride salt granules and optionally other ingredients, in a mould under a high pressure. In addition to the salt, a gelling agent or binder is added in order to solidify the blocks. The use of binders has raised some questions about possible negative effects on animals. Furthermore, some salts are not very suitable for compression moulding.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a solution that makes the use and handling of salt products more user-friendly. Hereto, the invention provides a method according to claim 1 and a salt body according to claim 14. A moulded salt body according to the invention only slowly dissolves in water and can be conveniently handled. In contrast to the known compressed salt bodies, the manufacture of a salt product as provided herein does not require the use of a gelling agent or binder. A cosmetic salt product of the invention can be held in the hand, allowing for rubbing a specific part of the body such that, at least locally, a high concentration of the beneficial salt or a solution thereof is in contact with the skin. The method according to the invention furthermore allows additives to be added to the salt in a simple manner. One reason why the manufacture of a salt product from a composition comprising MgCh.6H2O and/or CaCb.2H2O is advantageous is that these salt hydrates have a relatively low melting temperature, i.e. below 200°C. Shaped salt products in the form of the body may easily be moulded from such salts in molten condition. The salt body is solidified once its temperature is lowered to below its melting temperature. The composition from which the salt product is made may be provided in solid form or in the form of a brine, from which first some water is evaporated to allow the composition to solidify once its temperature is lowered below its melting temperature.

Particular embodiments of aspects of the invention are set forth in the dependent claims.

Further aspects, effects and details of the invention are set forth in the detailed description with reference to examples of which some are shown in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a first example of a salt product according to the invention while hand-held by a user;

Figure 2 shows a second example of a salt product according to the invention;

Figure 3 is a side view in cross-section of a third example of a salt product according to the invention; and Figure 4 shows a fourth example of a salt product according to the invention. MODES FOR CARRYING OUT THE INVENTION

Many but not all salts occurring in nature or purchased from chemical suppliers are hydrated; that is, a number of water molecules are bound to the ions in the crystalline structure of the salt. The most common salt, NaCl, does not form hydrates. Salt hydrates are formed when water makes up part of the crystal lattice formed by ions. The number of moles of water per mole of ionic substance is usually an integer. The chemically bound water molecules in salt hydrates is referred to as water of crystallization or crystal water. Salt hydrates have definite, stoichiometric, compositions depending on the demands of the crystal structure, and at any temperature possess an equilibrium water vapor pressure.

For some salt hydrates, increased temperature easily removes the bound water molecules, whereas in others they cannot be removed no matter how intense the heat, e.g., FeCb.6H2O. If the ambient water vapor pressure is less than this value, the water of crystallization is driven off and the crystal decomposes to a powder. This phenomenon (efflorescence) is exhibited by many hydrates. Further heating of the anhydrous powdered salt will result in thermal decomposition. However, in another type of salt hydrates, the crystal water is stronger bound and less easily driven off at increased temperatures. In that case, the crystal deliquesces and melts or dissolves in the crystal water. These salt hydrates are also known as low-melting salt hydrates because they can be liquefied at relatively low temperatures. Without wishing to be bound by theory, it is thought that, upon heating, the MgCl2.6H2θ and CaCl2.2H2θ salt hydrates dissolve in the water molecules that are present in the crystal lattice. Upon cooling below the melting temperature, the salt hydrate solidifies, presumably forming a hydrate again. In the present context, melting and, respectively, solidifying are to be understood as including such transitions from a solid to a liquid state or, respectively, from a liquid to a solid state. The present examples illustrate how these properties are used in the present invention for efficiently manufacturing a salt body of a predetermined shape.

To ensure the required coherence of a salt product in the form of a body as provided herein comprises at least 20% by weight, preferably at least 30%, more preferably at least 40% by weight of the MgCh.6H2O and/or CaCl₂.2H₂O salt hydrate. However, as will be understood the level of coherence of the final salt product will also depend on the nature of possible additives (see further below). The melting points of MgCl₂.6H₂O (around 117°C) and CaCl₂.2H₂O

(around 175⁰C) make these salt hydrates attractive for the manufacture of a salt product in the from of a body. Salt hydrates with higher melting points are economically less attractive (more heating and shape determining members such as moulds or substrates are required). In addition, as will be discussed below, salt hydrates with higher melting points do not allow the admixture of additives that are susceptible to thermal degradation at such higher temperatures. For example, many organic additives generally do not withstand temperatures over 200⁰C. Furthermore, the melting point is preferably above room temperature (appr. 20⁰C), more preferably above around 40-50⁰C. Salt hydrates with a melting point below room temperature are less attractive for practical reasons. Their application for the manufacture of a solid salt product in the form of a body as disclosed herein would require special measures such as cooling devices to allow the salt product to solidify. Moreover, the resulting salt product would also have a reduced thermal stability.

In a preferred embodiment, the salt hydrate comprises MgCl₂.6H2O, which salt hydrate is also known as Bischofite. Particularly good results can be obtained using a composition comprising at least 35% Bischofite. Bischofite is a crystalline salt hydrate left after evaporation of an ancient sea. As a mineral Bischofite is encountered as a glomeroblastic salt rock. Pure Bischofite crystals are aquatic-transparent, but may also be of white, rose and fallow colour depending on impurities.

It was found that Carnallite also forms in marine evaporite deposits where sea water has been concentrated and exposed to prolonged evaporation. Bischofite and Carnallite are extremely hygroscopic, in the open air they dissolve in water attracted from the ambient air. Bischofite is encountered on many continents, in formations of different ages including modern ones. There were discoveries of small deposits in Western Ukraine, Byelorussia and Kazakhstan. All the discoveries were represented by thin (3 to 7 m) non-extended layers. Most notable potassium and magnesium salt (including Carnallite) deposits are found in Carlsbad, New Mexico; the Paradox Basin in Colorado and Utah; deposits in Strassfurt, Germany; the Perm Basin, Russia and the Williston Basin in Saskatchewan, Canada. Another natural source of Bischofite and Carnallite is the region around Veendam, The Netherlands. NEDMAG INDUSTRIES Mining and Manufacturing B.V mines the Carnallite and Bischofite salt from the Zechstein salts near Veendam with a unique mining method.

A composition comprising MgCl2.6H2θ (Bischofite) for use in a method of the invention can be obtained by various means from natural sources, for example by solution mining or rock mining. Solution mining is used for the extraction of sulphur and salt from the Earth. To extract salt, water is pumped into the underground salt cavern. Here, the salt mixes with the water to form a brine solution. This solution is then easily pumped to the surface. In a preferred embodiment, a method of the invention comprises processing Bischofite brine composition obtained by solution mining into a salt product of a defined shape. However, the MgCh hydrate brine may also be dried to form coarse salt flakes which flakes are used in a method of the invention. In a more preferred embodiment, a composition comprises Bischofite brine or flakes obtained from the Zechstein salts near Veendam, as these appear to be relatively rich in bromide (5-6 g/1). Bromide is known for its soothing antiseptic qualities and has a pleasant relaxing effect on the whole body. A representative example of the composition of salt flakes obtained from heating a crude brine to 170⁰C followed by cooling is presented in Table 1. These flakes can be heated to about 130-140⁰C to prepare a molten salt hydrate that is advantageously used for the manufacture of a salt body according to the invention. Of course, it is energetically more attractive to start out from a brine comprising a suitable salt hydrate and heating this brine to evaporate excess water. It should be noted that the invention is not limited to the use of salt flakes with a composition according to Table 1.

Table 1

Typical Specification

MgCl₂.6H₂O % 47.3 46.5 min

MgSO₄ % 0.35 0.60 max

KCl % 0.55 0.80 max

NaCl % 0.65 0.90 max

CaCl₂ % 0.03 0.10 max

Br- % 0.60 0.70 max

H₂O % 50.5

Fe mg/kg 7 15 max

As mg/kg 0.1 max

Cd mg/kg 0.1 max

Pb mg/kg 1.0 max

Zn mg/kg 0.5 max

The shaping of a molten salt hydrate may be achieved by introducing a composition comprising the molten salt hydrate (i.e. molten MgCl₂.6H₂O and/or CaCl₂.2H2O) and optionally further additive(s)) into a mould. Many types of moulds can be envisaged. In one embodiment, the mould includes moulding cavity. Following introduction of the molten salt hydrate into the cavity, it is allowed to cool in said moulding cavity causing the salt hydrate to solidify in said moulding cavity into a body. Subsequently, the solidified body can be released from the moulding cavity.

In another embodiment, a die is used that is suitable for profile extrusion. Herein, the molten salt hydrate is forced through a die to extrude a continuous profile of the desired shape. These profiles can be a simple or highly engineered, solid shape, or hollow. Profile examples are numerous and include a rectangular, square, circular, oval, triangular or heart-shaped section. While still in the extruder die, the molten salt hydrate is cooled to allow (partial) solidification into a coherent mass that can be extruded out of the die as a continuous profile without disintegration. Following extrusion, the continuous profile can be sectioned into pieces of a desired length. This method is particularly attractive for large scale (continuous) production of salt bodies, for example for the production of salt tablets.

The shape may also be obtained by applying a molten salt hydrate to a cool substrate against which it solidifies in a shape determined by the shape of the substrate, as a layer at or around the substrate. Various additives and/or components can be added to the liquefied or molten salt hydrate such that they become incorporated in the shaped end product without the risk of burning or decomposition of the additive. In one embodiment, at least one additive is mixed through at least a portion of the molten salt hydrate, for instance before or after the molten composition has been introduced into a mould. The additive can have any physical state, e.g. a solid or a liquid state when added to the composition. It may be miscible with the liquefied salt hydrate such that a homogeneous mixture is formed. It may also be immiscible such that a heterogeneous mixture is formed wherein the additive remains discernible from the salt hydrate. Many types of additives can be thought of. Included are additives which can alter of affect the properties (e.g. appearance, smell or attractiveness) of the shaped end product. Examples of suitable additives for salt products for skin treatment are pigments, perfumes, fragrances, (essential) oils, such as lavender oil, almond oil, plant products, such as rose petals or apricot, and all sorts of components to decorate the interior of the soap such as dolls or other toys, dry leaves, lemon and orange rinds, flowers, seeds, playing balls, seashells. Also products that have a cosmetic or dermatological effect may be added, for instance an exfoliating agent such as coarse sea salt crystals, ground apricot-pits or crushed olive pits or a salt with known therapeutical and/or cosmetic properties, for example (Dead) sea salt crystals.

As said above, many salts do not melt in their own crystal water upon heating but their crystal water is driven off. Around the point of saturation and upon cooling, a semi-solid salt brine can be obtained containing small salt crystals. However, a solid salt body is not obtained. The present inventors found that the addition of MgCl2.6H₂O and/or CaCl₂.2H₂O to saturated salt brines of a salt which does not solidify on its own can be used to produce a solid salt body comprising the salt. In a specific aspect of the invention, at least 35% by weight solid MgCl₂.6H₂O (Bischofite) and/or CaCl₂.2H₂O is mixed with a (nearly) saturated salt brine and the mixture is further heated to around the boiling point of water, for example around 105°C. Upon cooling, e.g. in a mould, a solid salt body is obtained wherein the salt that normally does not solidify has "co-solidified" together with the MgCl₂.6H₂O and/or CaCl₂.2H₂O. Preferably, between 35-42% by weight solid Bischofite is used. Examples of salts that can be co-solidified into a salt body together with MgCl₂.6H₂O and/or CaCl₂.2H₂O are soda (Na₂CO₃), Carnallite

(KCLMgCl₂.6H₂O), Epsom salt, Dead See salt, and mixtures thereof.

When incorporated in a shaped product as provided herein, therapeutical or cosmetic salts can be rubbed onto the body or a specific part thereof such that a much higher (local) concentration of the beneficial salt can be obtained compared to application of the salts in the conventional granular form. Herewith, the invention provides use of a shaped product according to the invention as a therapeutic agent. Obviously, better therapeutic effects can be expected with a higher salt concentration. It is possible to incorporate one or more additives in the shaped end product. It should be noted that a solid additive or component does not need to melt when added to the molten salt hydrate. Rather, in various cases it is preferred that a solid additive or component remains solid throughout the whole procedure of solidifying from a molten state. For example, when a solid surprise object is to be incorporated or when a granular or crystalline salt other than a low -melting salt hydrate is added to confer the product with an exfoliating action. The salt body is preferably of a pre-defined shaped. In one embodiment, a so-called 'surprise' object is incorporated in the salt product, for example a little plastic or rubber animal figure. Upon use of the salt product in an aqueous environment, the salt surrounding the surprise object will gradually dissolve, thereby slowly revealing the surprise object. The surprise object may be added to the liquefied composition either prior to or after pouring the composition into a mould cavity.

The salt body may have a layered structure, i.e. consist of at least two distinct layers. For example, distinct layers are of distinct colour, structure, texture and/or fragrance. In one embodiment, the salt body has the appearance of a rainbow. The distinct layers may be visible at the surface when the product is still intact or they may be hidden to become visible only when the product is in use and outer salt layers slowly dissolve. A layered structure can be obtained by various rounds of moulding with intermittent solidification of each distinct layer to prevent mixing of distinct liquefied compositions.

In another embodiment, the molten salt hydrate is shaped and solidified into a body that contains one or more cavities which can be accessed from the outside of the body. A cavity may subsequently be filled with an additive or a mixture thereof. Optionally, the cavity is closed off after filling making use again of a molten salt hydrate with a low melting point. In yet another embodiment, an object is at least partially immersed in a molten salt hydrate as defined herein such that, upon subsequent solidification of the salt hydrate, a salt coating layer is formed at the surface of the object. As mentioned before, the salt product can be a cosmetic product. A cosmetic product is any substance or preparation intended for placement in contact with the various external parts of the human body with the intention of cleaning, perfuming, or protecting, to keep such parts in good condition, to change their appearance or correct body odours. Examples of cosmetic shaped salt products according to the invention are bath or shower tablets. In another embodiment, the salt product is an animal feed supplement in the form of a body comprising a low-melting point salt. In contrast to conventional salt licks produced by compressing moulding that requires various (undesired) additives like binders, a salt lick according to the invention can simply be manufactured by the melting and subsequent solidification in a desired shape of a low -melting point salt hydrate. Of particular interest is an animal lick comprising MgCh.6H2O. Magnesium is an important animal feed additive. For example, magnesium supplements are required to treat grass tetany. Grass tetany (cattle) or grass staggers (sheep) occurs when blood magnesium levels fall below a critical level. This occurs when animals are running on pasture which has low available levels of magnesium, or as a result of increased body demands for magnesium during lactation or late pregnancy. Grass tetany can affect stock in late autumn, winter and spring and cause significant losses in production, even when there are no signs of illness. At present, magnesium supplements are presented to animals in the form or a granular or flaky form. For example, MgO and MgCO3 granules are used as animal feed supplements. However, these conventional magnesium feed supplements have two major drawbacks. First, the granular and flaky form of a magnesium salt have a poor weather resistance and high wastage. Second, magnesium has a bitter taste and the granules are not very well taken by the animals. Both drawbacks can be overcome with the manufacture of a magnesium salt product in the form of a body like a block according to the present invention using MgCb.6H2O. The bitter taste of magnesium is advantageously masked by the addition of a palatable additive, such as molasses. Other suitable low -melting point salt hydrates, or mixtures thereof, may of course also be used for the manufacture of an animal salt lick. Furthermore, an animal lick may also contain other beneficial additives, for example trace elements.

The manufacture of a MgCl2.6H2θ or CaCl2.2H2θ salt product in the form of a body has several advantages in terms of storage and shipping when compared to the conventional bulk products of these salts (typically flakes in case of MgCb.6H2O and prills in case of CaCb). The bulk density of a product in the form of a body is higher than that of the typical flakes or prills. The bulk density of CaCb prills is around 600 kg/m3. In contrast, solidified CaCb.2H2θ according to the invention has a density of 1850 kg/m3. With a percentage CaCb of 75%, the bulk density of a CaCb.2H2O in the form of a solid body is 1388 kg/m3, which is more than two-fold higher than conventional CaCb prills. However, CaCb/ H2O ratios below that of the dihydrate form (75% CaC12) also give useful solid bodies. The use of 68% CaCb yields useful results. In that case, the melting temperature is around 150⁰C. Of course, the compacted salt bodies can be less rapidly dissolved compared to the prills. Thus, in those cases where transport density is more important than the rate of dissolution, it is preferred to produce CaCb in its dihydrate form as solid shapes that can be easily and efficiently handled, e.g. blocks that can be stacked on top of each other. Also for MgCb.6H2O the bulk density of solid bodies is significantly higher compared to the conventional flakes. The bulk density of flakes in approximately 850 kg/m3

Figure 1 shows an example of a salt product in which the body 1 of the product is of such shape and dimensions that it can be conveniently handheld. It will be clear that the salt body can have any imaginable defined shape or form, in many different dimensions. For certain applications, the shape of the product is such that it can be easily accommodated in a hand. For example, for a salt product to be used as a rubbing salt block under the shower, it is convenient that the body of the salt product has a volume of at least 10 cm³, preferably at least 15 cm³, more preferably at least 20 cm³. To allow for a quick and efficient application, the body preferably has an application surface, generally facing in one direction, and having a surface of at least 20 cm². Advantageously, the body has a thickness of at least one half of a cm such that it has a sufficiently stable structure for hand -held use. It may be a single use or a multiple use salt product. Because a salt product of the invention will be hygroscopic, a single use salt product may be preferred. The body of a single use salt product can have a net salt volume of approximately 5-10 cm³ and it may have the shape of a tablet containing a low cost disposable core. Figure 2 shows a salt product formed by a body 1 in the shape of an animal figure. Of course many other shapes of the salt body are conceivable, such as: a ball, a tablet, a geometrical shape such as a cube or a pyramid, a bar, an animal figure, a maritime figure such as a shell, a fish, a seahorse, a toy figure, a fruit figure, a heart, a cookie, a torso, a Spiderman, a Superman, a Batman, a Mickey Mouse, a Mini Mouse.

The application of the salt to a human skin, for instance for cosmetic treatment, comprises moistening at least the skin or a hand-held salt body, rubbing the hand-held salt body over the skin causing salt from the hand held salt body to dissolve and to be left on the skin in an, at least initially, dissolved form.

As mentioned, the salt body may be formed upon solidification of a molten salt composition in a moulding cavity. Moulds can be of various different materials, provided that the material withstands the temperature of a molten salt hydrate. For example, metal, ceramic, silicone moulds are suitably used in a method of the invention. Moulds are preferably of a pre- defined shape, but may also be to some extent deformable. For instance a bag of a suitable film material may also be used as a mould.

The salt product may further include a carrier connected to the salt body constituted by the salt composition. The carrier is advantageously attached to the salt body during the manufacture of the salt product by positioning the carrier or a portion thereof in the moulding cavity as an insert, before or after the molten composition is introduced into the moulding cavity, such that it becomes connected to the salt body upon solidification. In one embodiment, the carrier is a twist-up applicator housing of the type wel known as a applicator housing containing for instance lip stick or a deodorant stick. In another embodiment, the carrier forms a handle, e.g. an arc-shaped hand grip, allowing for a comfortable and secure grip on the salt body, even after the salt composition has been almost used up. The carrier may also form a substrate supporting the salt body to avoid breaking-up of the salt body as it becomes thinner and accordingly weaker during use.

The salt product may further include an enclosure to shield the salt body from moisture in the ambient air when not in use. In a preferred embodiment, the salt product is provided with both a carrier and a cover or lid, the carrier and the cover or lid forming the enclosure when attached to each other.

In the example shown in Figure 3, the salt product includes a carrier 2 in the form of a handle grip and a cover 3. The carrier 2 and the cover 3 are shown in mutually attached condition in which the cover 3 is removably connected by a snap-lock connection to the carrier 2 and in which the carrier 2 and the cover 3 form an essentially hermetical enclosure such that the salt body 1 is mechanically protected and shielded from moisture when not in use.

As illustrated by Figure 4, the carrier need not be a rigid structure, but can also be a flexible structure. According to the present example, the salt product has a body 1 in the shape of a soap bar and the carrier is formed by a looped rope. The rope 2 can be used to carry the salt product on the body while in use as well as to store the salt product when not in use while minimizing contact points between the (moistened) salt product and another surface, so that staining is minimized.

The invention is further illustrated by the following example of material and process parameters which describes the manufacture of various salt bodies of a defined shape from salt flakes or brine comprising MgCl₂.6H₂O (Bischofite).

EXAMPLE

Example 1: Manufacture of a salt product in the form of a body starting from flakes of MgCh.6H2θ.

Materials:

- heatable drum adjustable energy source

- stirring or agitating equipment moulding device - flakes of Bischofite (MgCl₂.6H₂O) additives (optionally)

Methods:

An amount of salt flakes is placed in the drum. The drum and its contents are heated by the adjustable energy source to a temperature of approximately 150°C. As soon as the flakes start to melt, stirring or agitation of the melting salt flakes is required. The temperature is increased up to 17O⁰C while stirring to ensure optimal heat transfer. Typically, heating to around 150°C at which the flakes melt is effective. If there is no more solid material visible, the temperature is reduced to between 130 and 140°C. At this point, additives may be added to the molten salt hydrate. If an additive is heat labile, the temperature of the melt can be reduced prior to addition of the additive, as long as the salt hydrate remains liquid (approximately 120°C). Thereafter, the salt melt is carefully transferred to a moulding device wherein the melt rapidly cools and solidifies.

If additives are added which may float or sag in the liquefied salt hydrate whereas a homogenous distribution throughout the end product is desired, it may be necessary to perform multiple rounds of moulding with intermittent solidification such that the end product is built-up layer by layer. It is also possible to place the additive(s) in a moulding device prior to pouring the molten salt hydrate in the device. In that way, the additive(s) will become enclosed by the solidified salt hydrate.

Once the solidified salt products are cooled to a lukewarm temperature, they can be released from the mould and provided with an air-tight wrapping.

Example 2: Manufacture of a salt product in the form of a body starting from a brine comprising MgCl2.6H2θ.

Materials:

- heatable drum adjustable energy source

- closed loop condensator - stirring or agitating equipment

- moulding device

- a brine comprising Bischofite (MgCb.6H2O)

- additives (optionally) Methods:

Because the starting material in this example is a brine (i.e. a crude aqueous solution of several salt hydrates), this brine is first heated to evaporate water to obtain a salt hydrate with an amount of crystal water in its crystal lattice that is suitably used in a method of the invention. Especially for large scale production, the evaporated water will need to be condensed because it may comprise small quantities of decomposition contaminants. For example in case of Bischofite small amounts of HCl are formed. As soon as the brine comprises the suitable salt hydrate, which for Bischofite requires heating to approximately 170°C, the same steps as described in example 1 above can be performed starting at the step wherein an additive can be added.

Example 3: Manufacture of a salt product in the form of a body comprising MgCl2.6H2θ, starting from a mixture of a brine and a melt or a mixture of a brine and salt flakes.

A combination of the different starting materials mentioned in Examples 1 and 2 (brine, flakes or melt) can be used to obtain a gel-like salt hydrate consisting of a melt comprising a major proportion of solidified salt crystals. Use of a gel-like salt hydrate as a starting material for the manufacture of a salt product in the form of a body minimizes the occurrence of unwanted phenomena during the solidification process, for example enclosed air bubbles or shrinkage cavities.

The materials and methods required are described in Examples 1 and 2.

Claims

1. A method for the manufacture of a salt product in the form of a body, comprising:

- providing a composition comprising MgCl2.6H2θ and/or CaCh.2H2O salt hydrate; - heating said composition causing the salt hydrate to be brought in a molten condition;

- bringing a liquid volume of said heated composition into a shape; and

- allowing said volume of said heated composition to cool causing the salt hydrate to solidify in said shape.

2. A method according to claim 1, wherein said composition comprises at least 20% by weight, preferably at least 30%, more preferably at least 40% by weight of the MgCl₂.6H₂O and/or CaCl₂.2H₂O salt hydrate.

3. A method according to claim 1 or 2, wherein said composition comprises at least 35% by weight of MgCl₂.6H₂O.

4. "A method according to any one of claims 1 to 3, wherein the salt hydrate to be molten is provided in a solid form, in the form of an aqueous solution (brine) or a form containing a combination thereof.

5. A method according to any one of claims 1 to 4, wherein bringing said composition comprising a molten salt hydrate into a shape comprises introducing said composition into a moulding cavity.

6. A method according to any one of claims 1 to 5, wherein at least one additive is contacted with at least a portion of the composition comprising the salt hydrate, while the salt hydrate is in the molten state.

7. A method according to claim 6, wherein said contacting comprises mixing said at least one additive through at least a portion of the composition comprising the molten salt hydrate.

8. A method according to claim 6, wherein said contacting comprises immersing at least a portion of a component in the form of a body in said composition comprising the molten salt hydrate.

9. A method according to any one of claims 6 to 8, wherein said additive or component is selected from the group consisting of fragrances, pigments, cosmetic substances such as oil, scrubs and cleaning agents, decorative shaped objects, animal feed ingredients and salts.

10. A method according to claim 9., wherein said salt additive is selected form the group consisting of Na2Cθ3.H2θ, Carnallite, NaCl, MgSCM.βH^O and Dead Sea salt.

11. A method according to claim 10, comprising mixing MgCb.6H2O and/or CaCl2.2H2θ in an amount of at least 35% by weight with a saturated solution of one or more of said salt additives, heating said mixture to at least 105°C and allowing solidification of said mixture.

12. A salt product in the form of a body, obtainable by a method according to any one of claims 1 to 11.

13. A salt body comprising a salt hydrate solidified to a predetermined shape from a state in which the salt hydrate is molten.

14. A salt body according to claim 12 or 13, having a layered structure.

15. A salt body according to claim 12-14, having a volume of at least 10 cm³.

16. A salt body according to any one of claims 12 to 15, having a thickness of at least one half of a cm.

17. A salt product according to any one of claims 12 to 16, wherein said product is a cosmetic product, such as a bath salt or a shower bar.

18. A salt product according to claim 17, wherein the body has an application surface, generally facing in one direction and having a size of at least 20 cm².

19. A method of applying a salt to a human skin, comprising: - moistening at least the skin or a hand-held salt body;

- rubbing the hand-held salt body over the skin causing salt from the hand held salt body to dissolve and to be left on the skin in an, at least initially, dissolved form.

20. A method according to claim 19, wherein the salt is applied for cosmetic treatment.