WO2018095897A1

WO2018095897A1 - Producing dispersants for solid suspensions from vinasse type materials

Info

Publication number: WO2018095897A1
Application number: PCT/EP2017/079887
Authority: WO
Inventors: Shailesh SANGLE; Ulf Velten; Harald RIEBANDT
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2016-11-22
Filing date: 2017-11-21
Publication date: 2018-05-31
Anticipated expiration: 2019-05-22
Also published as: MX2019005860A; BR112019010104A2; CO2019006595A2

Abstract

A method for producing a dispersant for mineral suspensions comprises the steps of: a) Providing a vinasse type material as a feed material; b) Passing the feed material through at least one nanofiltration stage in order to separate the feed material into a retentate phase and at least one filtrate phase; c) Collecting the retentate phase previously obtained and providing it as the dispersant.

Description

PRODUCING DISPERSANTS FOR SOLID SUSPENSIONS FROM VINASSE TYPE MATERIALS

Technical field The invention relates to a method for producing a dispersant for mineral suspensions, a dispersant obtainable by this method and to a method for producing a mineral suspension. Additionally, the invention is concerned with a mineral suspension comprising a dispersant and a molded body obtainable by hardening of a mineral binder composition. Background art

Dispersants for mineral suspensions are widely used in construction industry. Especially, dispersants are used as plasticizers or water-reducing agents for hydraulically setting compositions, such as mortars and concrete. Water-reducing agents allow for reducing the amount of water which is used for preparing hydraulically setting compositions without negatively affecting rheological properties or workability of the hydraulically setting compositions. Moreover, thanks to the reduced fraction of water, the strength of the hardened mortars or concrete can be improved.

Most effective dispersants for hydraulic binders like cement or plaster are synthetically produced substances such as naphthalene sulfonic acid- formaldehyde condensates, sulfonated melamine-formaldehyde condensates and polycarboxylates or polycarboxylate ethers. However, all these substances are based on fossil raw materials such as petroleum or natural gas. Lignosulfonates are used as an alternative for the above mentioned synthetic dispersants. Lignosulfonates are natural waste products from the pulp and paper industry using a sulfite pulping process of wood. In contrast to the above

mentioned synthetically produced dispersants, lignosulfonates are waste products which are based on renewable raw materials.

Recently, dispersants derived from modified renewable materials, based on e.g. cellulose or starch, have been proposed as dispersants as well.

Additionally, other raw materials based on renewable materials may be added to concrete water reducer which either give a certain water reduction or which are used to adjust the setting time. Suitable materials to mention are products derived from hydrolyzed cellulose or starch like glucose/corn syrups (with varying amounts of glucose, oligo- and polysaccharides), glucose, gluconate, hydrogenated glucose products or waste products like vinasse (from bioethanol, citric acid or yeast production) or molasses (from sugar production). Even other sugar types may be used.

Especially in a constantly growing market and due to ecological reasons, dispersants based on renewable raw materials are gaining more and more importance, because the dependency from crude oil can be reduced.

Nevertheless, despite the fact that some dispersants based on renewable sources are already known and in use, it is an ongoing challenge to provide dispersants based on renewable raw materials which fulfill cost-benefit ratios and performance requirements.

However, renewable raw materials or by products of industrial processes may comprise a relatively large amount if halides, especially chlorides. In particular, chloride contents can be as high as 1 - 10 wt.-%. When using such materials e.g. as dispersants or setting retarders for binder compositions, the corrosion of reinforcement structures may become a serious problem. Consequently, there are standards or recommendations which are regulating the maximum allowed chloride content in concrete admixtures (see e.g. standard EN 934-1 ) or in concrete (see e.g. standard EN 206-1 , recommendation ACI 222R or ACI 318/318R). Therefore, various renewable raw materials cannot be used as concrete admixture due to their too high chloride content, although the water reduction or the set retarding properties in concrete would be sufficient enough. Hence, they can only be used if they are purified before. In this regard, WO 2005/062800 A2 (Batchelder et al.) describes a process in which a lignosulfonate-containing feed stream of industrial residue is treated by electrodialysis and filtration to remove solids and certain small molecules and ionizable components present in the feed, to form a lignosulfonate product of enhanced quality. However, electrodialysis is a complicated and costly technique. There is thus a need to develop new and improved solutions which reduce or overcome the aforementioned drawbacks.

Disclosure of the invention

It is an object of the present invention to provide methods and dispersants which do not have the above mentioned drawbacks. In particular, a beneficial method for producing dispersants based on renewable raw materials or by products of industrial processes shall be provided. Preferably, the method should allow for producing dispersants with a loss of active raw material as low as possible, a high through put and without excessive maintenance, cleaning or regeneration needs of the equipment. At the same time, the method should make it possible to obtain dispersants with a high solid content. Especially, the method should also allow for producing dispersants with a proportion of halides, especially chlorides, as low as required for applications as concrete admixtures, in particular as low as needed to pass local standards regarding chloride content in admixtures or in concrete.

Moreover, the dispersants should be obtainable as economic as possible. Surprisingly, it has been found that the problem of the invention can be solved by the method according to claim 1 . Thus, the core of the invention is a method for producing a dispersant for mineral suspensions comprising the steps of: a) Providing a vinasse type material as a feed material; b) Passing the feed material through at least one nanofiltration stage in order to separate the feed material into a retentate phase and at least one filtrate phase; c) Collecting the retentate phase previously obtained and providing it as the dispersant.

As has been shown, the inventive method allows for a very efficient reduction of halide concentration, especially of chloride concentration, in vinasse type materials which are by products of industrial processes. In particular, the halide

concentration can be easily lowered to pass local standards regarding chloride content in admixtures, e.g. according to EN 934-1 .

Moreover, the inventive method allows for directly treating liquids of vinasse type materials with high solid contents, e.g. in the range of 30 wt.-% or higher, at rather low temperatures of for example 25 - 40°C with very high feed rates. Thereby, the loss of vinasse type materials has been shown to be very low. At the same time, the inventive method does not require excessive maintenance, cleaning or regeneration needs of the nanofiltration stage. This is highly advantageous from an economic and ecological standpoint since the amount of energy and time required to produce the dispersants can be reduced to a minimum.

The fact that an effective reduction in halide concentration can be achieved in combination with a low loss of vinasse type materials and a high throughput comes with great surprise. Typically, when effectively reducing impurities in materials to be cleaned, a large amount of the material to be cleaned is lost. However, surprisingly, this occurs in much lesser extent with the inventive method.

Also, it has been shown that the inventive method can be used to increase the solid content of vinasse type materials. Hence, while reducing the proportion of halides in vinasse type materials it is possible to increase the solid content of vinasse type materials at the same. This is for example highly interesting in terms of transportation because a reduced amount of water will reduce the overall weight and volume to be transported without reducing the total amount of active or solid material. Moreover, vinasse type materials produced according to the inventive method have been proven to be highly suitable as additive for conventional dispersants. Also, the vinasse type materials produced according to the present invention have been shown to be compatible with many conventional dispersants and other concrete additives.

Further aspects of the invention are the subject matter of other independent claims. Especially preferred embodiments of the invention are the subject matter of the dependent claims.

Ways of carrying out the invention A first aspect of the invention relates to a method for producing a dispersant for mineral suspensions comprising the steps of: a) Providing a vinasse type material as a feed material; b) Passing the feed material through at least one nanofiltration stage in order to separate the feed material into a retentate phase and at least one filtrate phase; c) Collecting the retentate phase previously obtained and providing it as the dispersant.

According to another aspect, the invention relates to a use of at least one nanofiltration stage for producing a dispersant for mineral suspensions from vinasse type material. Thereby, the use preferably comprises the steps of: a) Providing a vinasse type material as a feed material; b) Passing the feed material through the at least one nanofiltration stage in order to separate the feed material into a retentate phase and at least one filtrate phase; c) Collecting the retentate phase previously obtained and providing it as the dispersant. Especially, the nanofiltration stage is not used in combination with an electrochemically based filtration stage, in particular the nanofiltration stage is not used in combination with an electrodialysis stage. Especially, this means that neither the feed material provided to the nanofiltration stage nor a retentate phase and/or a filtrate phase is passed through an electrochemically based filtration stage or an electrodialysis stage.

In the present context a "vinasse type material" stands in particular for materials comprising or consisting of byproducts obtained in industrial processes involving processing and/or fermentation of sugar and/or sugar derivatives. Especially, a vinasse type material is a byproduct of bioethanol, yeast and/or citric acid production and/or a byproduct of corn and/or starch processing. Especially, the vinasse type materials are derived from sugar cane, sugar beet, corn and/or starch, especially sugar cane and/or sugar beet. Also, the vinasse type material can for example be a corn steep liquor. The latter is typically obtained as a byproduct of corn wet-milling. Such materials are typically flowable or liquid and comprise a certain amount of water. It is possible that these materials are available in powder form, too. Preferably, the vinasse type material or the feed material, respectively, is a liquid.

According to a preferred embodiment, the vinasse type material consists of vinasse, in particular vinasse derived from sugar cane and/or sugar beet. Vinasse can be treated with the inventive method in an especially efficient manner.

In particular, the halide content, especially the chloride content, of the vinasse type material used in the present invention is from 1 - 10 wt.-%, especially 2.5 - 5 wt.- %, with respect to the dry weight of the vinasse type materials. Vinasse type materials as obtained as byproducts from industrial processes may have a solid content of 3 - 5 wt.-% with respect to the total weight of the vinasse type materials. However, preferably, vinasse type materials are concentrated, e.g. by removal or evaporation of water, to obtain a higher solid contents for use in the present invention. Thus, especially preferred, the vinasse type materials or feed material used in the present invention may initially have a solid content of about 10 - 70 wt.%, especially 20 - 60 wt.% or 30 - 60 wt.% with respect to the total weight of the vinasse type material or the feed material, respectively. Depending on the used feed stock of the vinasse producing processes (bioethanol, citric acid or yeast) the composition of the vinasse may vary. Preferably, in the present context, a sugar content of the vinasse may be 0.5 - 20 wt.-%, especially 2 - 15 wt.-%, with respect to the dry weight of the vinasse. A proportion of protein may be in the range of 8 - 50 wt.-%, especially 10 - 40 wt.-%, with respect to the dry weight of the vinasse. Especially, the vinasse is derived from sugar cane and/or sugar beet.

The vinasse type materials shall be purified by using a filtration method. "Nanofiltration" is a membrane-based filtration method that uses in particular nanometer sized through-pores that pass through the membrane. Typically, a pore size in nanofiltration is about 0.001 - 0.002 μηπ, especially about 0.001 μηπ. A molecular weight cut-off (MWCO) with nanofiltration is in particular in the range of 100 - 8Ό00 Daltons. The "molecular weight cut-off" refers in particular to the molecular weight at which 90% of the analytes (or solutes) are prohibited from passing the membrane.

In the present context, the "filtrate" is the phase that predominantly passes the membrane whereas the "retention phase" is the phase which is retained or kept by the membrane.

Nanofiltration should however not be mixed up with microfiltration, ultrafiltration or reverse osmosis: Although microfiltration is as well a membrane-based separation process using membranes, the pore size is approximately 0.03 to 10 μηπ and a molecular weight cut-off (MWCO) is usually greater than 100Ό00 Daltons. With ultrafiltration the pore size is approximately 0.002 to 0.1 μηπ and the MWCO is about 10Ό00 to 100Ό00 Daltons. In reverse osmosis, the pore size is even lower than with ultrafiltration and the MWCO is below 100 Daltons. Thus, nanofiltration membranes have pore sizes smaller than that used in microfiltration and ultrafiltration, but larger than that in reverse osmosis.

Preferably, the at least one nanofiltration stage comprises a membrane having a molecular weight cut-off (MWCO) in the range of 100 - 8Ό00 Daltons, especially 1 10 - 5Ό00 Daltons, in particular 150 - 1 Ό00 Daltons, especially preferred 200 - 800 Daltons, for example 200 - 300 Daltons.

Using a nanofiltration technology with such small pore sizes or MWCO to separate halides from small organic materials like organic acids, proteins, sugars etc., it would normally be expected that i) with a small pore size only halides are separated while the throughput is very low, or ii) with a bigger pore size a higher throughput can be achieved but besides the halides a remarkable amount of small organic material passes the membrane, too, and is consequently lost.

It was now surprisingly found that with vinasse type materials, an effective separation of halides without heavy loss of active material in combination with a high throughput is possible with this technique.

Especially, the at least one nanofiltration stage comprises an inorganic and/or organic membrane, especially an organic membrane, preferably a polyamide based membrane and/or a polysulfone based membrane. Such membranes have been found especially advantageous when producing dispersants from vinasse type materials. In particular, such membranes allow for efficiently removing halides, especially chlorides, and at the same time obtaining a high throughput of feed material. For specific purposes or other feed materials, however, other membranes with a different molecular weight cut-off or made from other materials might be useful as well.

According to an especially preferred embodiment, step b) comprises or consists of the following sub-steps: b1 ) Passing the feed material through a first nanofiltration stage in order to

obtain an intermediate retentate phase and a first filtrate phase and b2) Passing the intermediate retentate phase once again through the first

nanofiltration stage and/or through a second nanofiltration stage, in order to obtain the retention phase and a second filtrate phase. Thereby, the first nanofiltration stage might be different from the second

nanofiltration stage. For example, the membrane of the first nanofiltration stage might be different from the membrane of the second nanofiltration stage, e.g. in terms of molecular weight cut-off, membrane material, pore size and/or structure. Using at least two nanofiltration stages in series surprisingly helps to optimize the removal of halide atoms, especially chloride atoms, while simultaneously ensuring a high throughput of feed material without clogging of membrane pores.

It is as well possible to foresee further nanofiltration stages. Thereby, preferably, the retention phase from a previous nanofiltration stage is passed through a further nanofiltration stage. This procedure further helps, to reduce the proportions of halide atoms, especially chloride atoms, in the retentate or the dispersant, respectively.

In a further preferred embodiment, the intermediate retentate obtained in step b) is diluted with a solvent, especially with water, before passing the intermediate retentate phase once again through the first nanofiltration stage and/or through a second nanofiltration stage. For dilution, with respect to the total weight of the intermediate retentate obtained in step b), 5 - 50 wt.-%, especially 10 - 30 wt.-% of solvent is added to the intermediate retentate. Such a dilution further helps to improve the overall process. The reduction of halide concentration depends on the initial proportion of halides in the feed material and the desired level of halides in the dispersant. Thus, preferably, the parameters of the inventive method are adapted accordingly.

For example, if a dispersant consists of 30 wt.-% of vinasse and the 30 wt.-% vinasse has a chloride content of 0.65 wt.-%, the chloride content needs to be reduced by 86 % to obtain a final chloride proportion of 0.09 wt.-% in the dispersant which is for example in line with the standard EN 934-1 .

In another example, if a dispersant contains only 25 % of a 30 wt.-% vinasse and the 30 wt.-% vinasse has a chloride content of 0.65 wt.-%, a four times higher chloride content of the 30 wt.-% vinasse can be accepted. This does mean that the chloride content of the 30 wt.-% vinasse has to be reduced from 0.65 wt.-% to a target concentration of 0.36 wt-.%, which corresponds to a reduction of 45% only. The final admixture based on 25% of a 30 wt.-% vinasse with a final chloride content of 0.36 wt.-% would pass the standard EN 934-1 with a final chloride concentration of 0.09%. Especially a halide concentration, in particular a chloride concentration, in the retentate phase collected in step c) is reduced by >10 wt.-%, especially 30 wt.-%, in particular > 50 wt.-%, preferably >70 wt.-% or even > 90 wt.-%, with respect to the halide concentration of the vinasse type feed material provided in step a).

In particular, a halide concentration, in particular a chloride concentration, in the retentate phase collected in step c) is reduced by 10 - 100 wt.-%, especially 20 - 90 wt.-%, in particular 30 - 80 wt.-% or 50 - 80 wt.-%, with respect to the halide concentration of the vinasse type feed material provided in step a).

Advantageously, a concentration of organic material, e.g. acids and salts of organic acids and/or proteins, in the retentate phase is reduced by less than 25 wt.-%, especially less than 10 wt.-%, in particular less than 5 wt.-%, preferably less than 2 wt.-% or less than 1 wt.-%, with respect to the concentration of organic material in the vinasse type feed material.

Preferably, the solid content of vinasse type materials or feed materials is increased when performing the inventive method. Especially, the solid content of vinasse type materials is increased by at least 5%, in particular at least 10%, especially at least 25%, preferably at least 40% or at least 60%, with respect to the initial solid content of the vinasse type materials. The increase of solid content is very advantageous because logistic costs can be reduced during transport.

However, the method may also be performed without concentrating the vinasse type materials.

Especially preferred, the inventive method or use does not comprise any

electrochemically driven separation processes, in particular it does not comprise electrodialysis of the feed material and/or of a retention phase. As found out in the present context, electrochemically driven separation processes such as

electrodialysis at least partially remove organic materials, in particular acids and acid salts, in the feed material. This in turn leads to a reduced water reduction when using the purified vinasse type materials as plasticizer for hydraulically setting compositions.

Additionally preferred, the inventive method or use does not comprise any ion exchange processes of the feed material and/or of a retention phase. Due to the rather high proportions of halides to be removed from vinasse type materials, ionic exchange requires excessive maintenance, cleaning or regeneration. From an economical point of view and in terms of technical effort, such processes are disadvantageous in the present context.

Nevertheless, for specific purposes additional electrochemically driven separation processes or even purification steps using ion exchange technologies or combinations of it might be an option, too.

According to a preferred embodiment, in step b) and/or during nanofiltration, the vinasse type material is subjected to a pressure of 0.5 - 500 kg/cm², especially 1 - 250 kg/cm², in particular 5 - 100 kg/cm², preferably 10 - 75 kg/cm² or 20 - 50 kg/cm². Thereby, the pressure is given with regard to a conventional standard value of the gravitational constant of 9.80665 m/s².

Also, preferably, step b) is performed at a temperature of 5 - 95°C, especially 10 - 75°C, in particular 15 - 55°C, especially preferred 20 - 45°C or 22 - 28°C. In particular, the temperature during step b) is at most 55°C, preferably at most 45°C, especially at most 40°C.

In particular a feed rate of the vinasse type material in step b) is 1 - 100 m³/h, especially 2 - 75 m³/h, in particular 3 - 50 m³/h, particularly preferred 5 - 20 m³/h.

Such process parameters have been proven to be very beneficial in terms of process efficiency, economical aspects and ecological aspects. This in particular if the dispersants are produced from vinasse.

Further preferred, before step b) the feed material is passed through a mesh filter, especially with a mesh size from about 15 - 300 μηπ, preferably 25 - 200 μηπ, especially preferred 30 - 70 μηπ. The so obtained filtrate can then be used as the feed material in step b). Even more preferred, before step b), the feed material is passed through a microfiltration stage, especially with pore size from about 0.1 - 10 μηπ, preferably 1 - 8 μηπ, especially preferred 3 - 7 μηπ. The so obtained filtrate can then be used as the feed material in step b). Advantageously, the feed material is first passed through a mesh filter and subsequently the feed material is passed through a microfiltration stage. The so obtained filtrate is then used as the feed material in step b). Beneficial mesh filters and microfiltration stage are described above.

A mesh filter and/or microfiltration stage helps to eliminate interfering particles in the feed materials which in turn further increases filter efficiency at the

nanofiltration stage(s). However, other prefilter systems might be used as well or prefilter systems might be avoided.

Another aspect of the present invention is concerned with a dispersant for mineral suspensions, obtainable or obtained by an inventive method as described above. Such a dispersant can be used for example as a dispersing agent, plasticizer and/or water reducer for mineral suspensions and/or mineral binder compositions, in particular for hydraulically setting mineral binder compositions, especially preferred for cementitious mineral binder compositions. However, the dispersant might as well be used as a dispersing agent for other purposes. Thus, a further aspect of the present invention is related to a use of a dispersant as described above as a dispersing agent, plasticizer and/or water reducer for mineral suspensions and/or mineral binder compositions, in particular for hydraulically setting mineral binder compositions, especially preferred for cementitious mineral binder compositions. The dispersant is used in relation to the mineral material, especially the mineral binder, preferably with a fraction of 0.01 to 10 wt.-%, especially 0.1 to 5 wt.-% or 0.5 to 2 wt.-%. The fraction here pertains especially to the solid content of the dispersant. The dispersant according to the present invention can be used alone or in combination with one or more plasticizers. Thereby, the one or more plasticizers are in particular chemically different from the dispersant according to the present invention. According to a preferred embodiment, the inventive dispersant additionally comprises a plasticizer, especially a plasticizer selected from the group consisting of polycarboxylates, polycarboxylate ethers, vinyl co-polymers, lignosulfonates, naphthalene sulfonic acid-formaldehyde condensates, sulfonated melamine- formaldehyde condensates. According to a further preferred embodiment the inventive dispersant may comprise a setting retarder which even may show plasticizing effects. The setting retarder is for example derived from hydrolyzed cellulose and/or starch. Especially, the set retarder is for example a glucose/corn syrup (with varying amounts of glucose, oligo- and polysaccharides), glucose, gluconate, hydrogenated glucose products and/or or waste products like further vinasse type materials or molasses (sugar production) as well as other sugar or sugar acid types.

Advantageously, the plasticizer involves in particular a polycarboxylate, especially a polycarboxylate ether. In particular, the plasticizer is a comb polymer comprising a backbone to which anionic groups and/or their salts and polyalkylene glycol chains are connected. The polycarboxylate ethers are normally produced in a polymerization process or via a polymer analogous condensation reaction.

Such comb polymers are also distributed commercially by Sika Schweiz AG under the brand name ViscoCrete^®.

By the combination with a plasticizer, the properties of the dispersant can optimally be adapted to different requirements.

In one especially preferred embodiment, the plasticizer has a fraction in the dispersant of, for example, 1 to 95 wt.-%, especially 2 to 50 wt.-%, in particular 3 to 30 wt.% or 5 to 20 wt.-%. Furthermore, the dispersant can optionally comprise one or more additives in particular, a defoamer, a colorant, a preservative, another dispersant, a retarder, an accelerator, an air pore forming agent, a shrinkage reducer, a viscosity modifier, a stabilizer, a biocide and/or a corrosion inhibitor or combinations of these.

Another aspect of the present invention is related to a mineral suspension, in particular a mineral binder composition, comprising a dispersant as described above or a dispersant which is obtainable or obtained by an inventive method as described herein. In the present context, the term "mineral suspension" stands in particular for a heterogeneous mixture containing solid mineral particles that are dispersed throughout a fluid phase, which is in particular a liquid, especially containing or consisting of water. A weight ratio of liquid phase to mineral particles lays preferably in the range of 0.2 to 0.8, especially 0.3 to 0.7, preferably 0.4 to 0.6. By "mineral binder" is meant in particular a mineral based binder which reacts in the presence of water in a hydration reaction to form solid hydrates or hydrate phases. This can be, for example, a hydraulic binder (such as cement or hydraulic lime), a latent hydraulic binder (such as slag), a pozzolanic binder (such as fly ash or natural pozzolans) or a nonhydraulic binder (plaster). Especially, a "mineral binder" or "mineral binder composition" can be a

"cementitious binder" or a "cementitious binder composition" meaning in the present case in particular a binder or a binder composition with a fraction of at least 5 wt.-%, especially at least 20 wt.-%, preferably at least 35 wt.-%, especially at least 65 wt.-% cement clinker. According to another preferred embodiment, the binder or a binder composition is at least 95 wt.-% made up of cement clinker.

In particular, a "cementitious binder" or a "cementitious binder composition" is based on cement which is defined e.g. in the standards EN 197-1 or ASTM C150 or ASTM C595. A fraction of the cement clinker in the overall "cementitious binder" or a "cementitious binder composition" preferably amounts to at least 5 wt.-%, especially at least 20 wt.-%, preferably at least 35 wt.-%, especially at least 65 wt.- %. According to another preferred embodiment, the "cementitious binder" or a "cementitious binder composition" is at least 95 wt.-% made up of cement clinker.

But it can also be advantageous for the "mineral binder" or the "mineral binder composition" to contain other binders in addition to or instead of a hydraulic binder. These are, in particular, latent hydraulic binders and/or pozzolanic binders.

Suitable latent hydraulic and/or pozzolanic binders are, e.g., slag, fly ash, silica dust and/or natural pozzolans. Likewise, the binder composition can contain inert substances such as ground limestone, ground quartz, and/or pigments. In one preferred embodiment, the mineral binder contains 5 to 95 wt.-%, especially 5 to 65 wt.-%, particularly 15 to 35 wt.-% of latent hydraulic and/or pozzolanic binders.

Especially, the mineral suspension is a mineral binder composition containing a mineral binder and a dispersant as described above. A fraction of the dispersant in relation to the mineral binder amounts in particular to 0.01 to 10 wt.-%, preferably 0.1 to 5 wt.-% or 0.5 - 2 wt.-%. The fraction here pertains especially to the solid content of the dispersant. The mineral binder and the dispersant are defined here as described above. The binder composition can be present for example in dry form or as a fluid or stiffened binder composition made with added water.

In another preferred embodiment, the binder composition additionally contains solid aggregates, especially gravel, sand and/or aggregates. Corresponding compositions can be used, for example, as mortar mixtures or concrete mixtures.

In particular, the binder composition contains in addition water, wherein a weight ratio of water to mineral binder lays preferably in the range of 0.25 to 0.8, especially 0.3 to 0.7, preferably 0.4 to 0.6. Such binder compositions can be worked directly as mortar mixtures or concrete mixtures. Furthermore, the invention is also related to a molded body, which is obtainable by hardening of a binder composition as described above after adding water. The molded body so produced can have practically any desired shape and it can be, for example, part of a construction project, such as a building, a wall or a bridge. Another aspect concerns a method for preparing a mineral suspension, in particular a mineral binder composition, whereby a dispersant as described above, is added to a mineral material, especially a mineral binder, preferably a hydraulic mineral binder. The dispersant can for example be mixed in with the add water for the binder composition, which is then used to stir the binder composition. It is also possible to add dispersant or the composition containing same directly to the mineral material or binder and to mix in the add water before and/or later on, if necessary. Even it is possible that only one part of the dispersant is mixed with the add water and the other part is added before, with and/or after the addition of the add water to the binder composition.

Furthermore, in a further aspect of the invention, the inventive dispersing materials can even be added during the cement production, alone or in combination with commercially available cement additives to influence grindability of cement and/or cement properties of ground cements. Further advantageous embodiments and combinations of features of the invention will emerge from the following exemplary embodiments and the totality of the patent claims.

Exemplary embodiments

1 . Producing dispersants 1 .1 Method

Fig. 1 shows a schematic illustration of an inventive method for producing dispersants.

Specifically, two different processes P1 and P2 with different parameter sets (cf. table 1 ) have been performed. Both processes were stated with the same untreated vinasse obtained from the bioethanol production using sugar beet on sugar cane as vinasse type feed material FM. Then, in first step, the feed material FM was passed through a mesh filter MeF and a micro filter MiF. The so obtained filtrate was then subjected to a two stage nanofiltration treatment. Thereby, the prefiltered feed material was passed through a first nanofiltration stage S1 in order to obtain an intermediate retentate phase IR and a first filtrate phase F1. Subsequently, the intermediate retentate phase IR was diluted by addition of water W (20 wt.-% with respect to the total weight of IR) and passed through a second nanofiltration stage S2, in order to obtain the retention phase R and a second filtrate phase F2. Thereby, the first and the second nanofiltration stage were identical in terms of membranes.

Table 1 gives an overview of the parameters used in processes P1 and P2:

Table 1: Process parameters

In order to investigate the processes, the solid contents and proportions of chloride ions in various phases have been measured. The solid content has been measured after drying at 120°C and the chloride content was measured according to EN 480-10. Table 2 gives an overview about the results obtained.

Table 2: Results (all numbers in wt.-%)

IR 39.69 1 .13 22.09 1 .41

F1 - - 5.74 9.18

R 36.36 0.49 22.98 1 .33

F2 6.62³> 8.25³> 3.81 8.85

1 ) with respect to the weight of the solid content of the respective phase

2) with respect to the solid content

3) Content of intermixed filtrates F1 and F2 As evident from table 2, the inventive method clearly allows for reducing the chloride content the values below 0.5 wt.-% (P1 ) or 1 .4 wt.-% (P2) in the final retentate phase R when compared with the initial content in the feed material FM. Consequently, the chloride content in filtrate phases F1 and F2 is significantly increased. Noteworthy, that the process conditions can be adjusted to achieve higher solids content after the filtration process. E.g. for process P1 with vinasse from bioethanol production, the solid contents in the retentate phases (IR, R) are even higher than the solid content of the feed material (FM). This means that the vinasse is concentrated during the filtration process. Hence, the inventive method can be used to reduce the amount of halides in vinasse type materials and at the same time increase the solid content of vinasse type materials.

In another trial a vinasse type material was used obtained from the production of yeast as disclosed in the patent EP 3 026 032 A1 . Using analogous process parameter as for P1 (table 1 ) in a further process P3, a similar chloride reduction like with vinasse based on bioethanol can be obtained (cf. table 3).

Table 3: Results (all numbers in wt.-%)

Phase

Solids¹' ^; CI- ²> v,. , . FM 39.14 1 .49

IR 25.99 0.75

1 .2 Dispersants

The retentate phase R resulting from process P2 has been used as dispersant D for further testing.

Specifically, the following dispersants DO, D1 and D2 have been provided or produced, respectively:

DO: Sika^® Plastocrete (a commercially available mid-range water reducing admixture from Sika based on 32 wt% of lignosulfonate; for comparison).

D1 : An aqueous mixture based on 24 wt% of lignosulfonate and 8 wt.-%

dispersant D.

D2: An aqueous mixture based on 1 6 wt% of lignosulfonate and 1 6 wt.-%

dispersant D. 2. Concrete tests

2.1 Concrete compositions

The dispersants were tested in concrete mixtures. For this, a concrete was used with the composition as specified in table 4.

Table 4: Concrete mixtures

The dispersants were used as an aqueous solution with a fraction of 0.5 wt.-% of the total binder content consisting of cement and fly ash. The dispersants were mixed in advance with the amount of water used for the concrete so that a homogenous solution was obtained. For the concrete production, the sands, aggregates, cement and fly ash were added in a drum mixer and the dry mix was mixed for 30 seconds. Afterwards the water, including the dispersant, was added and the wet mix was mixed for additional 3 minutes. 2.3 Test methods

To determine the effectiveness of the dispersant according to the invention, the slump of the concrete mixtures was measured immediately after preparing the concrete and also after 30 minutes and 60 minutes. Furthermore, the compressive strength of the concrete mixtures was determined 3 days (3 d), 7 days (7 d), 14 days (14 d) and 28 days (28 d). Also, the setting time of the concrete mixtures was determined.

The slump of the concrete, compressive strength and the setting times were determined according to ASTM standards.

2.4. Results Table 5 gives a summary of the results obtained with various dispersants. Please note that the tests with dispersant DO (not produced according to the invention) have been done for comparison. Table 5: Effects of dispersants in concrete mixtures

It is evident from Table 5 that dispersants D1 and D2, both comprising vinasse which have been treated according to the inventive method, are highly similar to the commercially available lignosulfonate based dispersant DO in terms of plasticizing effect, set retardation and compressive strength.

Thus, the data shown above clearly show that dispersants which are produced according the present invention have after the purification process the desired properties of fresh and hardened concrete. Moreover, the dispersants according to the invention are compatible with existing mid-range water reducers and can be used for such kind of water reducers in different combinations.

It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricting.

Claims

Method for producing a dispersant for mineral suspensions comprising or consisting of the steps of: a) Providing a vinasse type material as a feed material; b) Passing the feed material through at least one nanofiltration stage in order to separate the feed material into a retentate phase and at least one filtrate phase; c) Collecting the retentate phase previously obtained and providing it as the dispersant.

Method according to claim 1 , wherein the at least one nanofiltration stage comprises a membrane having a molecular weight cut-off (MWCO) in the range of 100 - 8Ό00 Daltons, especially 1 10 - 5Ό00 Daltons, in particular 150 - 1 Ό00 Daltons, especially preferred 200 - 800 Daltons, for example 200 - 300 Daltons.

Method according to at least any of claims 1 - 2, wherein the at least one nanofiltration stage comprises an organic membrane, especially a polyamide based membrane and/or a polyethersulfone based (PES) membrane.

Method according to at least any of claims 1 - 3 wherein step b) comprises the steps of: b1 ) Passing the feed material through a first nanofiltration stage in order to obtain an intermediate retentate phase and a first filtrate phase and b2) Passing the intermediate retentate phase once again through the first nanofiltration stage and/or through a second nanofiltration stage, in order to obtain the retention phase and a second filtrate phase.

5. Method according to at least any of claims 1 - 4 wherein before step b) the feed material is passed through a microfiltration stage, especially with pore size from about 0.1 - 10 μηπ, preferably 1 - 8 μηπ, especially preferred 3 - 7 μηπ and/or wherein before step b) the feed material is passed through a mesh filter, especially with a mesh size from about 15 - 300 μηπ, preferably 25 - 200 μηπ, especially preferred 30 - 70 μηπ.

6. Method according to at least any of claims 1 - 5, wherein the method does not comprise electrochemically driven separation processes, in particular it does not comprise electrodialysis of the feed material and/or of a retention phase.

7. Method according to at least any of claims 1 - 6, whereby a halide

concentration, in particular a chloride concentration, in the retentate phase collected in step c) is reduced by >10 wt.-%, especially 30 wt.-%, in particular > 50 wt.-%, preferably >70 wt.-% or even > 90 wt.-%, with respect to the halide concentration of the vinasse type feed material.

8. Method according to at least any of claims 1 - 7, whereby a concentration of organic materials, specially organic acids and salts of organic acids and/or proteins, in the retentate phase is reduced by less than 25%, especially less than 10%, in particular less than 5%, preferably less than 2% or less than 1 %, with respect to the concentration the organic material in the vinasse type feed material.

9. Method according to at least any of claims 1 - 8, whereby in step b) and/or during nanofiltration, the vinasse type material is subjected to a pressure of 0.5 - 500 kg/cm², especially 1 - 250 kg/cm², in particular 5 - 100 kg/cm², preferably 10 - 75 kg/cm² or 20 - 50 kg/cm².

10. Method according to at least any of claims 1 - 9, whereby the solid content of vinasse type materials or feed materials is increased when performing the inventive method, whereby, preferably, the solid content of vinasse type materials is increased by at least 5%, in particular at least 10%, especially at least 25%, preferably at least 40% or at least 60% with respect to the solid content of the vinasse type materials as provided in step a).

1 1 . Method for producing a mineral suspension, in particular a mineral binder composition, whereby a dispersant obtainable or obtained by a method according to at least any of claims 1 - 10, is added to a mineral material, especially a mineral binder, preferably a hydraulic mineral binder.

12. Dispersant for mineral suspensions, obtainable by a method according to at least any of claims 1 - 10.

13. Dispersant according to claim 12, additionally comprising a plasticizer,

especially a plasticizer selected from the group consisting of

polycarboxylates, polycarboxylate ethers, vinyl copolymers, lignosulfonates, naphthalene sulfonic acid-formaldehyde condensates, sulfonated melamine- formaldehyde condensates and/or carbohydrates.

14. Mineral suspension, in particular a mineral binder composition, comprising a dispersant according to claim any of claims 12 - 13 and a mineral material, especially a mineral binder.

15. Molded body, obtainable by hardening of a mineral binder composition

according to claim 14, after adding water.

1 6. Use of a dispersant according to at least any of claims 12 - 13 or a

dispersant obtainable by a method according to at least any of claims 1 - 10, as a dispersing agent, plasticizer and/or water reducer for mineral suspensions and/or mineral binder compositions, in particular for

hydraulically setting mineral binder compositions, especially preferred for cementitious mineral binder compositions.

17. Use according to claim 1 6, wherein the dispersant is obtainable or obtained with a method which does not comprise electrochemically driven separation processes, in particular it does not comprise electrodialysis of the feed material and/or of a retention phase.

18. Use of at least one nanofiltration stage for producing a dispersant for mineral suspensions from vinasse type material.

19. Use according to claim 18 wherein the nanofiltration stage is not used in combination with an electrochemically based filtration stage, in particular the nanofiltration stage is not used in combination with an electrodialysis stage.