CA1113246A - Synthetic firelog incorporating binder made from liquid combustible by-product - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A synthetic firelog is made by binding cellulosic particles with a combustible binder produced by the interaction of a liquid combustible by-product or waste product and a modifier, the resulting material being such as to be carbonizable on combustion to form a porous skeleton which maintains the shape of the log during burning. The by-product may be molasses, various waste oils or pitches, or sulphite lye and the modifier interacts physically or chemically therewith to form a plastic, thixotropic binder material. The cellulosic material may be sawdust, paper, or any of a variety of cellulosic residues from the processing of vegetable materials.

Description

~L~13Z~i _ELD OF THF. INVENTION
The present invention relates to synthetic fire-logs, and more particularly to synthetic firelogs made without wax, or with a reduced wax content.

BACKGROUND OF THE INVENTIO_ Conventional synthetic fireplace logs generally contain up to about 65% by weight of oil refinery slack waxes which are physically admixed with finely divided wood particles and extruded into the desired log-like shape.
However, with reserves of crude mineral oil dwindling, ener-gy conservation is becoming increasingly important, and the prices of oil-derived products are rapidly increasing. Syn-thetic firelogs, although generally quite fuel-efficient, are increasing in price. Moreover, with more important end uses for the waxes available, such as conversion to gasoline or plastic monomers, it is unlikely that sufficient slack waxes of adequate quality will be available for use by the synthetic log industry in the future. Some of the "waxes"
now available are in fact more in the nature of refinery slops, and are quite unsuitable for conventional methods of synthetic firelog manufacture.

-; SUMMARY OF THE INVENTION
- It has now been found that synthetic firelogs may be manufactured using materials other than slack waxes if such materials can be treated to give the logs manufactured therefrom the desired properties.
According to the invention, a synthetic firelog comprises a log-shaped extruded mass of a material of suffi-cient dimensional stability to hold its shape at normal room , 30 temperatures, ,; .

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and carbonizable on combustion to provide a porous skeleton wh:Lch will substantially maintain the configuration of the log, the material comprising a mixture of 25~ to 70~ by weight of particles of solid cambustible material, the balance consisting essentially of a combustible solid bin-der, the binder consisting of at least about 15% by weight of the log of at least one normally liquid combustible by-product, and a further component interacting with said liquid combustible by-product to solidify the latter and form said binder, the combustibility of the extruded mass being such as to provide a safe but aesthetically acceptable rate of burning under firegrate conditions from the time the log is fully alight until substantial consumption of the volatilizable content of the log.
By by-products are meant secondary or waste pro-ducts resulting from a process of making some other product, and mixtures of such products.
In one form of the invention, the solid combus-tible material includes preferably about 35%-40% by weight of a particulate cellulosic material which carbonizes to form the skeieton. Enough cellulosic material may be present to form during burning a porous carbonized skelton which substantially maintains the shape and dimensions of ; the log. The formation of such a skeleton may also be achieved or assisted by the formation of coke on combustion of the liquid combustible waste product, or by an alterna-tive or additional further component which either carbo-nizes to ...................................................

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~13Z~i form a suitclblc skeleton, and/or itself provides such a skeleton.
Tn some cases, the at least one further component can entirely con~ist of particulate cellulosic material which not only forms the skcleton but i5 able selectively to absorb liquid components from the liquid by-product and reduce the latter to an extrudable solid, whilst in other instances the at least one further component provides a structure within which the liquid by-product is dispersed to form an extrudable solid, the structure also providing the skelekon on combustion of the log. In most cases, however, at least two further components will be utilized, one, which will usually be particles of cellulosic material, with the primary function of forming the skeleton, and the other with the primary function of solidifying the li~uid by-product. Either ~ component, together with further.components and modifications ~:
to the physical structure of the log may be utilized to ~ -; achieve the desired rate and completeness of burning of the . log. Thus the combustion properties of the log may be controlled :
by one or more of the shaping of the log, the inclusion of ~ .
flaws or flaw inducing means in the log, the character and . particle size of the particulate material, the inclusion of ~:
a combustion modifying additive, controlling the order and , ~1 ~,. vigor of admixture of the various ingredients, and the selection . of the by-product.and the further component or components.
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~ The component or components interacting with the by-product . . .
` may comprise one or more substances combining physically there-,~: with to a solid solution or gel or other solid dispersion, . - 4 -, ~ ~ .
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~nd/or chemic~lly therewith to form solids.
Suitable liquid combustible by-products include pitch residues from the treatment of vegetable or animal materials;
asphalts and coal tar pitches, creosote residues; sugar refininy by-products; organic by-products of pulp and paper production; used, spent or spoiled lubricating or industrial or cooking oils; crude soaps or ~atty residues from the soap industry; crude oils and fats or residues thereof from industries processing vegetable or animal oils, by-products 10from the manufacture of starches and polysaccharides; and refinery bottoms, slops and oil pitches.
In order to convert the foregoing materials into -:
extrudable solids that can be combined with cellulosic : particle~ to ~orm satisfactory synthetic fire-... . .

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l.ogs, thcy aro combinecl with modi:Ler.q selec-tcd to provide thc nece~ssal.y so~idifyi.ny and/or plastici~ing e~ec-t such as ~atty ~cids, fa-tty acld salts, ol- ~lycerides; waxes; solid solu~ion forming synthetic polymers; synthetic or natural surfac~ants, soaps; rosins and rosin modified plastics;
synthetically modified natural products such as stear~tes and gums; solid hydrocarboIIs either natural or synthetic; and lignosulphonates, lignin or sulphite lyes. In some cases, one licIuid combustible waste or by-product may be used ~s a modifier for another such product, or the waste or by-product may partially replace a fuel conventionally used in firelogs, ..
such as slack wax, which itself acts as a modifier for the :~
waste or by-product.
In order to permit e~ficient combustion of the synthetic firelog, the following further materials may be ~. .
included in the fuel-modif-er mixture in order to control the ~ ~ .
combustibility of the resulting log: non~porous extenders, such as clays, graphite, coal dust,diatomaceous earths, silica, mica etc, oxidising agents to assist combustion such as per-borates, peroxides or persulphates; acid generating media to catalyse thermal degradation; alkaline media to block thermal polymerisation or produce higher melting point materials;
chemically active materials to assist in ring openiny or double bond breaking; fire retardants to extend burning times;
and low flash point liquids and solids to maintain continuous combustion.
~fficient combustion of the synthetic firelogs may also be assisted by the selection of the shape of the &xtxuded logs. The lo~s may have grooved surfaces to assist in the -- 6 ~

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prop~tion of tl-e flaines; or may be hollow, or extruded with holes th~rein or therethrough Conventionally shapea logs may ~l~o be produced with intention~l flaws therein, or with a~ents included therein to inducing flawing or cracking duriny burning and thus assist in the complete combustion of the log.
Further features of the invention will be apparent from the following more detailed description of preferred embodiments.

S HORT DESCRI PTIO~ OE' THE DRP-WI~G
In the drawing:
Figures lA, 2A and 3A show different form~ of extruded firelog, and Figures lB, 2B and 3B show, diagrammatically, relevant portions of apparatus for extruding such logs.

DESCRI PTION OF TE~E PREE~ERREI) EMBOD~ TS
In the following description, all parts and percent-ages are by weight, unless otherwise stated.
Among the combustible liquid by-products which may ~20 be used in the manufacture of the novel synthetic firelogs of the present invention are:
Veqetable Pitches and Tall Oil Pitches and Sulphite ~yes These materials are respectively by-products of the destructive distillation of vegetables, seeds, leaves and flowers; by-products of destructive distillation of timber;
and by-products of the destructive extraction of cellulose fom timber to form paper.
Vegatable seeas such as coconut, soyabean, sunflower, corn, ~round nut, almond, olive, palm, castor, babassu, cotton, _ 7 _ 32~6 ]inseecl, oi-ticia, perilla, canbra, safflower, sesame, and tung arc cnemically scparated on a large scale to proauce such fatty acids as stearic, oleic, linoleic, linolerie, palmitic, myristic, lauric and ricinoleic acids. Complex mixtures of these and many other ac;ds obtained are then separated into refined or semi-refined blends or euts, and have many uses in the manufaeture of soaps, varnishes, paints, plastics and cosmetics. A viscous dark eoloured piteh remains after the removal of the useful aeids, and eontains high lQ molecular weight acids and organie dehris. ~his vegetable piteh ean usefully be eonverted into a solid fuel suitable ~ !
for synthetie log manufaeture.
A similar material, a by-produet of the destruetive distillation of wood, is ealled tall oil pite~h. By a similar process, the useful aeids and ehemieals are removed from wood to leave a dark viseous end produet, having a similar eompc)si-tion to vegetable pitch and eomposed of organie high moleeular weight aeids and debris. The ehemieal eonstituents o tall oil piteh are generally more unsaturated or higher in aromatie eontent then those of vegetable piteh.
Sulphite lyes are produeed from timber as a by-produet of the paper industry. When paper is made from wood, the reslnous organie eonstituents are dissolved out of the eellulose eells in th~ form of aqueous solutions of sulphates, sulphonates or sulphites. The solutions, eommonly having 40-60% solids eontent, are ealled "lyes" or "liquors" and generieally "sulphite",lignin or "ligno" deseribes the salt procluet~ EIenee, they are eommonly ealled "sulp~ite lyes", "lignosulphonate liquor", "lignin liquor" or even more qenerally pulp liquor"
In order to U5e the foregoing materials in log manu fac ture, the pitches, which can vary from hiyhly viscous, sticky liquids having a ~iscosity o~ 3000-15000 centiposes at 20C to mobile viscous ].iquids or slurries of viscosity as low as a few hundred centiposes, are converted to extrudable solids. Ideally the fuels used for synthetic firelogs are firm solids at room temperature and thus hard logs which will transport without damage are obtained. It has been found that the viscous vegetable ana tall oil pitches can be converted into extrudable solids by the incorporation of suitable modifiers such as (1) solid fatty acids or fatty acid salts, such as sodium stearate, oleate and l.inoleate, or the corresponding alumLnium, calcium, barium, potassium or strontium salts; .

(2) petroleum or natural waxes such as paraffin, slack, micro-crystalline, carnuba, montan and bees' wax.

(3) wood resins and modified wood resins such as rosin esters of various types, dimeric rosin acids, poly-merised resins dehydrogenated resins, hydrogenated resins, and alkyd and phenolic copolymers of rosin;

(4) synthet.ic high molecular weight polymers such as poly-: ethylene, phenolic novolacs, polyethylene glycols, polybutadienes, silicones, polyxylene, polybutylene, polyiso~utylene, polypropylene, ethylene vinyl acetate polymers, and polyvinyl pyrollidone;
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(5) synth~tic surfact~nts such as nonylphenols with high ethylene o~ide contents, ethylene oxide propylene oxide copolymers (polyglycols), polyglycol ethersO aliph~tic oxyalkylated alcohols D and lauryl sulphate and laur~l sulphate ethers,

(6) solid hydrocarbons such as phenols, reSorcino naphthalene, quinolene, hydroquinine, ph~halates, ~lu~
tamic anhydride, naphthol, polystyrene and its copolymers and norbornene,

(7) saccharides, polysaccharides and their acid s~lts such as sucrose, sorbitol, mannitol, carboxymethyl cellulose, hydroxycellulose~, cellulose resins, starches, gums, alginates, proteins, xanth~tes and uronates; and

(8) fats such as lard, tallows, suets, butter, fish lards, and whale fat,

(9) neutralizîng agents i.e. alkaline materials which form with the acid components of the pitch salts which solidi~y or increase the viscosity of the latter. Suitable alkalis are for example sodium hydroxide, potassium hydroxide and sodium carbonate.
These may be added to the pitch before it is added to the sawdust or other particulate cellulosic material or directly to a blend of sawdust and pitch. Such neutralization also reduces coXing during bu~ning o the log and thus provides a more satisfactory perormance. However, it has a disadvantage when chemicals are added to the log composition to induce , 32g~

colourcd flames duriny burnin~. The normal chemicals used for this purpose are copper sulphate and cuprous chlo~ide, often with ammonium chloride added to i~prove volatility. Under strongly alkaline conditions such as those produced by sodium hydroxide or carbonate, the copper salts appear to be converted into copper oxides or non volatile salts since the flame colouring effect is noticeably reduced. The desirable solidifi-cation or Viscoslty increase which occurs on n~utrali-zation can be achieved without loss of flame colour by `-the use of weaker bases such as ammonia, ammonium carbonate, monoethanolamine or other organic amines.
Other methods of countering this interference re--action are however more convenient. Firstly, the pitch may be carefully neutralised before addition to the log mix so that no free alkalinity occurs to upset the colour inducing chemicals. A standard titration for free fatty acid on each batch of pitch may be used to determine the exact amount of alkali required which ~20~ may then be added to the pitch in a pre-blend tank - where with sufficient agitation and heat a neutral salt or "soap" may be prepared. Such a "soap" can then be maintained in molten form for subsequent addition to the log mix~ A simpler means of neutralization avoiding . .
` ` colour loss is to change the alkali ;n such a mann~r that it cannot contact the colour chemicals without first reacting with the pitch. Thus the chemicals may be added to the dry sawdust and mixed with sufEicient wax or other water insoluble material so that it i9 ,~ ' ' Z4~;
coate~l. Subsequent addition of pitch in the acid form follow~d by other fuels (wax etc) and finally the neutralizing alkali ensures tllat the risk of contact between the alka]i and colour chemicals is minimal.
I,ogs made by this method showed no deterioration or loss of flame colour whereas when the alkali was not separated from the colour producing chemicals some permanent loss of flame colour was observed.

(10) additives which copolymerize with the pitch acids to form solids, Such polymerization can be achieved by ~ -a variety of routes and the degree of polymerization or thermal stability of the pol~mer can be controlled to prevente~Y~sivecoking or flaring of the log. Suit-able additives or compounds containing active hydroxyl groups such as glycols, formaldehyde condensation polymers such as urea-formalde~de and phenol-formalde-hyde, paraformaldehyde, and epichlorohydrin. For example, the addition of 5 per cent by weight of para- -formaldehyde to a liquid bend of pitch and sawdust 20 ~ gave a solid which produced excellent logs with good burning properties.
~11) oxidizing agents. Oxidation of the pitches gives a significant increase in viscosity and csn result in the conversion of a liquid pitch into a solid pitch in some cases. This is believed to be caused by oxidative polymerization similar to that achieved in the production of oxidi2ed asphalts and castor oils.
The e~fect can be obtained hy the use of air passed '.

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thro~ the heated liquid pitch, or by the addition o~ solicl or liquid oxidizi~g agents such as perborates to tlle mixture.
Other solid or~anic material or liquids which can be con~erted into solids by, for example, neutralization or pol~nerization, may be suitable for modifying the physical structure of the pitches.
Low cost effectiveness and deleterious properties such as coking, toxicity, sooty flame, and rapid co~bustibility of some of the above groups or individual modifiers make them less desirable than others for use in synthetic firelogs.
The amounts of modifier required are determined by the need for the resulting material to be extrudable and essentially solid at normal ambient temperatures. Certain pitches from distillation plants where maximum recovery of "light ends"
is made, have such high viscosity as to require little modification, and as little as for example 0.25-2% by weight a suitably chosen modifier is sufficient to form a solid extrudable blend of the fuel, the modifier, and any further additives employed.
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The preferred modifiers are of course the less costly ones and comprise materials from all of the above mentioned groups, including fatty acids and salts; paraffin~
slack and microcrystalline waxes; wood rosins and their modifîed forms, polyethylene, phenolic novolacs, polyethylene .
~lycols, EVA polymers, nonylphenols, ethylene oxide-propylene oxide copolymers, polystyrenes, sugars, ca~bohydra~es, starches, gums, all forms of fats or glycerides, and ligno-sulphonates.

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3Z~i usiny 100 parts by wei~ht of a typical pitch as a s-tar-tin~ material, a fuel that is a firm solid at room temperature may be obtaincd by thc addition of the amounts specified of the following modifiers:
stearic acid, 5-10 parts; hydrogenated ylycerides, 5-10 parts; aluminium stearate, 2-5 parts; aluminium octoate, 1-2.5 parts; coonut mono ethanolamine 2-5 parts; nonylphenyl (50 EtO) 2-5 parts; polyethylene glycol (M.W 6000), 2-5 parts; sodium oleate, 3-10 parts; sodium linoleate, 2-7 parts; wood resin, 3-10 parts; lignosulphonates, 1.5-6 parts;
sugars 3-8 parts; polysaccharides 0.25-1 part~
Most of the above ranges of modifier content are suitable for both medium and high viscosity vegetable or :~
wood pitches. Particular blends may also give other desirable features such as smooth extrusion without plugging, and less sooty burning. Specifically, the fatty ~ 20 ~

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acids and glyceride~ or fatty ~cid salts are particularly satisfac~ory ~or obtaining these t~lo f~atures. The salts are known ind~strially as lubricating so~p~ and hence addition of these ensures a good lubrication during extrusion of the logs E~owever, some of the free solid fatty acids polymerise under mild oxidative conditions and elevated temperatures and this can lead to excessive coking, Coking is caused by incomplete combustion, and gives a cohesive carbon structure that can produce a hard skin ~n the log ana result in suffocation of the flame, a very slow flame spread during initial ignition, and small flames with excessively long burning time~ for the log. Some degree of coking is desirable, as it gives predictable burning times for the logs and minimises the risk of the splitting or breaking up of the log upon combustion. It has been found that neutralisation of the fatty acids to form salt reduces coking, perhaps by removing the active hydrogen on the carboxy group and/or deactivating any active alcohol `~
side chains. In the case of oleic acid~ linoleic acid, etc.O
the neutral salt i9 the desired form for the same reasons, but also because this salt is a solid whereas the acid i5 a liquid. Wood rosins are o~ similax structure ¢hemically and hence these too are preferred in the neutralissa form even though they are hard brittle solids and can be used as free acids to give a solid solution with pitches. Similarly the acidic pitches may in SOmQ cases be neutralised to optimise their properties. Hence b~ careful select$on of the addit$ve and degree o~ neutralisation an ideal blend can be selected.

Gl~ceride~ ar~ also capable of polymeri.zation and coking, acid or alX~line media re~ulting in the hydrolysis of the ester bond with improved combustionr Other methods of controlling coking have also been found. Unsaturated acids or glycerides burn more readily as a result of the oxidative double bonds e,g, oleic, lineoleic and linolenic acids burn more readily with less coking than does stearic aci~ or hydrogenated glycerides.
Suitable modifiers are hence blends of stearic, oleic, linoleic, lineolenic acids which may be partially or wholly neutralised.
The neutralisation may be carried out prior to compounding of the log mix; for example caustic soda in solid or liquia form is added to the acid in predetermined amounts in a suitable mixing vessel. The molten salt produced may then be blended with the pitch ~or addition to the remainder of the log mix or added directly into the log mix before or after the pitch, preferably after the pitch in order to take advantage o~ its lubricating property during extrusion of the logs.
Neutralis.ation may also be carried out directly in the log mix, for example, by adding caustic soda, sodium carbonate, aluminium : 20 hydroxide, or o~her alkali to the mixture before or after the addition of the acidic material. A more desirable alternative, since the final mixture has to be cooled to allow extrusion, is to preneutralise the acid to it~ salt and prepare it in the form of a powder or flake for addition to the log mix.
; This means that the heat of reaction produced during neutralisation and the latent heat of liquification of the prQduct~ do not have to be removed from the mixture before it is extruded.

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-~3~as6 coXin~ may also be reduced by the inclusion in thl~ mix of ~ non porous powderea extender such as graphite, china clay, silica)diatomaceous earth, etc. Thi~ extends the liquid phase over a larger surface area part of which is non porous and as a result the cohesion of any carbon coke skeleton foxmed during combustion is reduced. For example, the addition of 5 parts of china clay to 100 parts of a mix which exhibits severe coking and flame suffocation results in reduced coXing and a more continuous burn. A similar effect can be achieved by controlling the particle size of the wood waste car~ier or any wicking agent employed. Meaium sized wood particles 1/10" 20 mesh 40 mesh and 60 mesh give su~ficiently little surface area that the film thicknes~ obtained when coated and saturated with the fuel at normal ratio by we~ght (40:60) i~ signiffcant and the carbon skeleton (coke) therefore has a degree of cohesion. If very fine sawdust is used e.g~ 80 - 100 mesh the additional surface area to be wetted results in a thinner fuel film and hence a less cohesive coke skeleton. This has bee~ tested u9ing the following formula:
Wood Particles 37.5 pts. by wt.
Tall oil pitch 50.0 pts~ by wt.
Stearic acid lO.O pts. by wt, When made with normal ~ized sawdust ~circa 20 mesh) the log suffocated and extinguished itself leaving a hard coked skin and unburnt;fuel trapped inside. Replacing the coarse sawdust with 80 - 100 mesh wood flour gave a much improved log _ 17-~3Z~

with a l~ coh~siv~ co}~ed shell ancl co~npl.ete comb~lstion was acl~i.eve~ 1ith th~ me formula using circa 20 m~sll particles a s;milar improvernent ~s made by the addition of 5 parts china clay or 9ilica or graphite.
Increasing the average particle si~e to coarser than 10 mesh also had the desired effect of ~educing coke coherence. Whilst the surface area oE the wood was in theory reduced giving a thicker fuel film, it was found that less solid fuel was required to produce a cohesive log. This resulted in the film thickness being similar to that with 20 mesh wood but the area of contact and number of contact points between the coarser particles was also reduced, and a more complete burn and a less cohesive ash was obtained.
Tt has also been found that the tendency to coking is reduced when the sawdust is partially or wholly replaced by nut-shell fines, bagasse or paper pulp.
Lignosulphonates are usually manufactured in salt form as a paper mill by-product, and may be used to modify the pitch to provide the desired extrudability and solidifi-cation. They are supplied as dark free flowing hydroscopic powders and can be added directly to the sawdust or other cellulosic component of the mixture before or after the pitch or dissolved in the hot pitch prior to spraying on the wood particles.
Starches, sugars, proteins, polysaccharides and carbohydrates in general are suitable for addition to pitches as modifi rs. The materials are typically produced from sugar cane, sugar beet, various woods, palm nuts, maplet sorghum, millet, potatoes, corn, etc. Sugars (disaccharides .
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~Ip to ~ o~ cch~ri~l~s) al-;o h~v~ a uscful calorific value, but as tllcir rnolecular wei~ht increases ~he tendency to cause cokinc~ incrcases. This m~y be controll~d or r~duced by the inclusion in tlle lo~ mix oE oxidizing aq~ntS such as peroxides, nitrat~s, persulphates or perbor~tes at l~vels up to 15%.
An alterna-tiv~ method is to induc~ fission by inclucling in the mix fugitive acids such as aluminium sulphate, ammonium chloride, or acid anhydrides, which on heating or combining with water driven off during combustion become acidic. Acid hydrolysis of the polysaccharides pro~uces readily combustible organic materials such as sorbose, dextrose, glucose, fructose and hexoses. Addition of reducing agents also produces more ready combustion. ~ -Sulfite lyes or liquors can be made suitable for use by methods similar to those described for pitches and molasses, except that neutralization is not applicable as they are already neutral salts in aqueous solution. For example, addition of polyethylene glycols, lecithin pitch, sorbitol, mannitol, nonylphenol adducts at 40 mol ethylene oxide or gelatine can be used to convert these liquids into the preferred solid or semi-solid extrudable material. As the water content of the lyes is relatively high (up to 60%) the amount of modlfier required is proportionately highex e.g 10-20% of soaps or polyethylene glycols are required for lyes or 10-30% nonylphenol adducts or lecithin. This renders the lyes relatively expensive fuel sources and they are bet-ter used as a diluting component for higher viscosity material such as molasses. The burning properties of lyes and ligno-sulphonates are generally better than pitches since they are ' ' .

24~i l~ss su~ ct: to ~>ol.yrn~ri z~t :ion ~n~ tllu~; have le~s tendency to cau~;~ cokin-~.
~iner~l Pitches,__sph.-llts, _oal ~rar Pitc_ec., Creosote e~i~ues In gencral al] ~he m~difications that can be appli~d to vegetable or wood pitches can also be applied to these materials. These residues also have acidic groups which can be neutralized to reduce cokiny. However, the aromatic con~ent of these by-products is generally higher than previously encountered and sooty flames resul~. This can be overcome ~o a large extent by the inclusion in the mix of suitable oxygen carriers such as nitrates, peroxides, perborates or persulphates.
Suqars, Syxups, Molasses The combustible material may be a waste or by-product rom the sugar industry since low grade sugars are a cheap source of heat.
Extraction of sugars from cane, beet, berries, millet, fruit, maple, etc. after crushing of the base under high~ pressure, solvent extraction or tapping, proceed~ in an established pattern; an initial crude liquor or syrup is obtained which in itself may be used as a fuel source when solidified by means discus~ea later in relation to molasses.
However, most sugar producing countries boil of~
excess water and filter to produce crude crystalline sugar called "muscovado", plantation white or "raws", together with molasses. During this initial conversion 96-97% of the sugars present are produced as crude crystalline sugars and 5~O as syrups or molasses - viscous dark liquids of sugar content as high as 86% by weight. Duxing processing, higher z~
mol(~c~l]ar ~ci(~ sacch~rides are precipi~ted out by treat-ment witll, or e~ample, llme to produce powdered calcium saccharat~s. These ~a]ts can be us~d as fuels i~ synthetic logs If solid or crystalline sugars are used in making ~ ~;
log5, the material is melted and sprayed on~o the wood chips as for a normal molten fuel. The extrudability of the mix may be improved by the inclusion of modifiers such as polyols, polyethylene glycols, EVA copolymers, modi~ied wood rosin esters, gums, waxes, fatty acids, fatty oils, alcohols or soaps.
Molasses is a more convenient and cheaper form of sugar for use as a fuel. It is liquid and can be pumped readily when warmed to a temperature as low as 80F. Despite containing 20% or more by weight water it burns ~uite well.
It can be readily converted into an extrudable solid form by the inclusion of relatively small amounts by weight of water soluble solids such as polyethylene glycols 0.5-So~; nonyl-phenols of high ethylene oxide content 1-10%; starches, gums ~20 or cellulose derivatives 0.25-5% gelatines, alginates or xanthates 0.25-2%; wood resins 1-10%.
A particularly useful modifier for molasses is the substance known as crude lecithin pitch, which is the end residue of the destructive aistillation of soya bean9.
Purified lecithin i~ used in many dietary foods and vitamin preparations in which it is claimed to have advantageous properties. However, the crude pitch is found ta exhibit a particularly useful property in that it will absorb the water present in molasses to form a solid. Blend5 of molas5es and _ 2~ -..
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lecithirl pi,~Cll irl ratios be-~ween 2:1 and 9:1 appear useful for log manuacture.
Waxes may also be u~ed -to solidify molasses when i,ncorporated into a log forming mixture. The wax is added last and preferably contains a small amount o~ an oil soluble emulsifier e.g. nonyl phenol ethoxylate, During the mixing process, the molasses is encapsulated in the wax, and on cooling a solid wax skin gives the log a cohesive structure.
Molasses to wax ratios between 1:1 and 4:1 may be so utiliæed.
,10 Other suitable modifier systems are similar to those discussed previously in relation to pitches.
Sugars and molasses tend to char and coke during combustion but this can be minimized by using the techniques ' previously discussed in relation to their u~e as modifiers for pitches.
A further series of problems are associated with water containing fuels such as molasses and lyes. Dapending on the finished log density, the problem may be minor in ~ nature or major. The synthetic logs currently on the market -~ 20 cover a wide range of density. Low density logs are extruded or formed using a relatively high speed but low compression ' ratio compactor or extruder. The log thus produced shows no signs of stress cracking but is larger in diameter to achieve ,' a standard weight to length relationship. It is cohesively weak being spongy or soft in texture and often does not handle well during packaging and shipping. Thus it is not uncommon for such logs to arrive at the point of sale broken into two or more pieces.
High density logs are hence preferred as they are .
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not only qu;te firm and hand]eable at the warm extrusion tem~rat~res b-~t on cooling they are hard and cohe~ive and very l;ttle clama~e is sustained during handling and trans~
por ta tion .
With low density logs few problems occur when using mola.sses even at relatively high levels e.g up to 40% of total log weight, alone or together with up to 20% of sulphite lye. f-Iowever, with high density logs some problems occur.
Using normal feed grade molasses having 25% water conkent, no unusual prablems occur when up to 25% of the wax is replaced -- e g. 40 pts sawdust, 15 pts molasses, 45 pts wax. Above this level of molasses the increased mbisture added via the molasses begins to plasticize the sawdust thereby making it increasingly elastic. If the higher solids sugar refinery grade of molasses (85% solids) is used, it can be used up to 25% of the total log weight before it too is donating sufficient water to effect the behaviour of the sawdust. When producing high density logs with high levels of molasses or lyes, swelling occurs as the logs leave the extruder and stress -~20~ ~ cracking develops in the log surface, whilst the logs feel ; springy and soft. The swelling and cracking associated with :: :
~ both gxades of molasses can be ovexcome if they are added in .
a particular manner as follows If the total charge of wood is divided into two ! ~ :
parts and the molasses is premixed with one portion, the pro- ~ ~
.
blems are almost eIiminated - certainly higher levels of the molasses can be used with no stress cracking. For example if 10 pts of sawdust a~e mixed with 25 pts of feed grade molasses a free flowing slightly tacXy material results. A

~ ':
- 2~ -,;

-- ~$3L32~i fu~ther 30 parts ~wdust are then mixed in followed by 35 pts of wax. The mix has the texture of and behaves like a normal all wax formula giving no swelling or cracking, Higher levels of t:he refinery molasses can be similarly incorporated with no serious softening of the log. It appears that the improve-ment is as a result of confining the donated moisture to only a portion of the sawdust which is then dispersed by subsaquent additions with wax impregnated material. As a result the - springiness is dissipated and contained within the log giving little swelling and no visible cracking~ The molasses impregnated wood particles and the wax containing particles may be made as separate mixes, cooled as necessary and blendea , just prior to extrusion.
Replacing part of the sawdust by a cellulosic material which absorbs moisture less re,adily or is less affected by absorbed water also reduces the swelling and cracking. For example the use of peanut shell fines, cocoa bean shell fines, coconut shell or walnut shell fines, bagasse, or paper pulp in part or whole replacement of the wood sawdust gives a log less subject to swelling and cracking. If this modification is co~bined with the preblending technique excellent firm logs are obtained. The nut shell replacements ,~ have an additional advantage due to being less absorbent in that lower overall fuel levels may be employed and yet normal log appearance and performance is maintained. All or part of the sawdust may also be replaced by coal dust.
Using the two charges of sawdust in the form of a pre-blend also so~es two other opposing problems. If the molasses is added after the wax or soap fuel a sticky mix results Z4~;

which gives some build-up problem~ on transfer conveyors etc. The sticky mix can a~so run slower through the extruder or in extreme cases plugging of the extruaer can result with excessive ~riction induced back pressure. If the molasses is added to the entire wood charge and wax or soap fuel is added last, build-up and plugging are avoided, but coking of the molasses during the burn is increased with suffocation of the fire. Both prob~ems are solved by using the separate wood/fuel mix technique or preblend. Low levels of molasses may be satisfactorily incorporated by addition after part of the wax is charged and prior to the final por-tion of wax e.g. sawdust 40 pts, slack wax 22 pts molasses 15 pts, slack wa~ 23 pts added in order as written.
One final problem associated with water containing fuels is the temporary loss of flame colour. If the chemicals added to produce coloured flames are added simultaneously with, prior to or immediately after, molasses or sulphite lye, the coloured flames are not evident at normal intensity until the logs have matured for several days e.g. at least 4 days. It is thought that the cause is the solution of the chemicals in the m~isture donated by those aqueous fuels ~ which probably occurs particularly if the mix 1s warmed by ; addition of molten fuels, e.g. wax etc. Recrystallization on aging results in the reappearance of the coloured flames which improve in intensity to normal as the crystals grow in size~
It is on the other hand al50 possible to take advantage of the ab~orbency of sawdust of low moisture content and - ~5 -,. . . .

L3Z4~
some ot~ler cel].ulosic parti.cul.ate materials such as wood flour. If molasses is mixed with such materials, and the latter are allowed time to absorb moisture from the molasses, the moisture content oE the latter can be reduced to a level at which it becomes an extrudable solid, whilst the swelling and cracking problems discussed above are reduced since the cellulosic material has swelled prior to extrusion. The use of molasses alone with the cellulosic material will usually provide a log which burns too slowly and with exce~sive coking, but modifiers may be added to the molasses to avoid this, as already discussed above. Other materials may also be used in place of essentially cellulosic materials to absorb the moisture from molasses and to help provide the necessary skeleton for the log (although the coking of the molasses, even if reduced by modifiers, will contribute to the formation of such a skeleton). An example of such a material is soya flour or meal.
The selection of molasses type and lye aepends on cost Savings required, available cellulose base (nuts, shells, wood etc.) and manufacturing process. The lower solids molasses and lye are mobile liquids at ambient temperatUre ' i ~:~ ' ' . ' ' '.

.. ,. . . - :
:. . , . : ..
, , : , ~': ' ; ' ~IL3;2~3L6 and ~-~nc~ c~n b~ added cool. This reduces the efforts and costs involved in cooling the mixes to extrud~ble temperature.
Ilowever, the high solids molasses has a higher heat value and yives less problems as previously discussed. An ideal com-promise is to use a blend of high solids molasses and sulphite lye. For example 3 pts of 85% molasses, normally a highly viscous unpumpable liquid at ambient temperature, becomes a mobile liquid when mixed with one part 60% sulphite lye.
The blend is 75% solids and burns with less coking then a ~10 75% solids feed grade molasses. Alternatively 4 pts 85%
molasses with 1 part 60% lye gives a mobile liquid which can be pumped of total solids 80%, This blend has a better heat value then 75% molasses and gives less swelling etc. as previously discussed.
Many different types of molasses are avail~ble depending on the source e.g.
Cane Molasses ~, Origin Viscosity Viscosity CP at 20C CP at 20 C
ex factory feed grade (75% solids) Ecuador 28000 3250 Iran 7250 3250 - Pakistan 8550 1680 `
' Brazil 21100 ~650 ;
Jamaica 108200 10300 Trinidad 35560 4580 !,' Beet Molasses Belgium 5460 1460 Germany - 1~140 1800 Turkey 51700 2200 ~ussia 6700 2680 ~, From the viewpoint of viscosity at low temperatures, beet molasses is desirable, being lower in viscosity at the : - :

- ' .

~13;~4~ :
sai~ XJ~i.C~S c~nt~n-. El~ /ev~r, ff~r -r jr~ e~;s of~ th~ logs tl-~ re~er~ is tru~. ritos- nl)~a~eC; thicken anci so~e "gel"
i~l t}~e ~ ?';(`LlC~ c,~;phoric acic~ ox <,oine organic acids.
U~e can b~ ad~ of this ef~ct to "body~' up the mola~ses as sho~n in example 32. The ~cid is injected illtO the In~lass~s streall just prior to reaching the sawdust or the acid can be added to the wo~d/molasses ,nix immediately the molassec. has been added. The thicken~ng is thought to be due to hydxogen bonding induced by polari-~ation in the molasses.

A particularly useful means of controlling coking in the logs containing molasses is achleved by compoundinc~
the mix in a specific manner. In such a log, a double coking effect occurs. The residual resins and tar residues in the c~llulosic material, eg. wood, coke and produce a carbon skeleton of some cohesive strength ~uite naturall~ during the burn. Indeed this is why normal wax based synthetic logs are so successful: when formulaced properly, no sagging or dripping occurs as a result of the coking which occurs on partial co~bustion of the sawdust. The carbon skeleton acts as a porous but cohesive wick for the melting and burning fuel. When substantial amounts of mo1asses are introduced tabove 5% of the total weight of the log) the wood carbon skeleton is reinforced by the molasses coke to a point where suffocation begins (at above l~/o by weight of :
molasses). A dilution of the molasses coking effect .
can be achieved by preabsorbing all the molasses on part of the wood component eg. of the ~wo following formulae, identical in overall composition, formula B

shows markedly less suffocation than A as the second 32~;

charge o~ ~lntre~ted wood dilutes the molasses coking ef~ect.
A B
Sa~Jdust (1) 40 ~0 parts by weight Molasses 25 25 parts by weight Sawdust (2) ~ 20 parts by weight Slack Wax 35 35 parts by weight The ingredients were added consecutively in the order ~-shown and mixed thoroughly prior to subsequent additions.
Many useful and unexpected features occur with logs made - incorporating molasses viz:-(1) Reduced Smoke during burning ~;
.
Side by side comparisons of totally wax logs, wax plus pitch logs, and wax plus molasses logs show that with mola~ses visibly less smoke is evolved. The smoke normally is of two forms - white smoke which is a vapour of unburnt fuel eg. wax vapour or black smoke as a result of incomplete combustion. Totally wax loys can give undesirable amounts of the white smoke as a result of flash boilin~ at the surface. Pitch, particularly tall oil and coal tar give black smoke as a result of partial combustion of the aromatic components therein.
Either or both these components used in conjunction ' ~ .
with molasses give reduced smoke. It is believed the reduction in smoke is due to t~o effects - molasses has j oxy~en in its structure and hence should burn less ; smokily, but its tendency to coke also results in a slower release of other fuels present and hence a higher oxygen to uel xatio reduces the vapour smoke and blacX

5moXe. Reduced smoking is desirable not only for aesthetic . ~
, ~3Z~
reasons, hut ~lso because it reduces the formation of flamrnable d~posits in chimn~ys and flues.
(2) Increased E~ardness __ __ Despite molasses being a moblle or viscous liquid at room temp~rature, logs made using molasses are generally harder than when made with even the hardest of slack waxes. Slack waxes are most often derived from the dewaxing o-E lubricating oils and the texture of the resulting wax varies considerably depending on the dewaxing process, the source of the crude oil utilized and the type of lubricating oil being produced from the refinery tower. For example, American crudes produce quite soft slack waxes often with the texture of petroleum jelly or margarine whereas certain Canadian crudes yield slack waxes which are quite firm at room temperature.
In particular the higher the viscosity the oil being separated, the more cohesive and the higher the melting point of the slack wax by-product becomes. With the trend to using lower viscosity base oils in motor oils, the slack waxes produced have generally tended to become softer and/or of lower melting point. This trend in turn results in the production of softer synthetic logs - an undesirable effect since such logs do not handle well during ::
packaging and are subject to more damage during shipping and warehousing. The addition of molasses counteracts ~! this trend as shown by the following tests of the hardness of different log mixesJ thus enabling quite soft and ... .
mobile waxes or fuels to be used without producing a softer Log.

~ardness oE Log Mixes - Method a dial vernier with a spring return was modified ' -: ; . . ..

Z~

with a 3/16" cone p2rl~t:ration tip and a platform to take var~ing weigllts. The cone tip was placed on the surface to be tested and weights were added. Penetration was measured ov~r an elapsed time period, ie. the higher the penetration reading~ the soEter the surface.

The slack waxes used as a binder component of the log mixes axe listed in Table 1. Samples were ;~
made using 6~o by weight binder component and 4~/0 by weight sawdust, the compositions of the binder component and the resulting hardness readings being tabulated in -- ;
Table 2. ~ -The same hardening effect hae been observed ;
even when liquid fuels are used as a partial replacement of the slack wax, eg.
Li~uid Fuel Textuxe at Room Temperature Tall Oil Pitch (TOP) Viscous Liquid Vegetable Oil Pitch (VP) Thin Liquid Used Cooking Oil (UCO) Thin Liquid ~; Samples were made and tested as above, the compositions of the binder components and the resulting hardness readings being tabulated in Table 3.
The hardening effect of molasses is thought to be due to two main reactions. Firstly the moisture present in molasses and not present in slack waxes or pitches, may be preferentially`absorbed by the kiln dried sawdust conventionally utilized .in artificial firelogs leaving a solid molasses sugar residue on the outside of the wood-----------------------------------------------'~

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particl~c;. ~ probab]y mo~e signiEicant cause i.s the gellation ei~f~ct of acids on molasses. Some typ2s of molasses have been kr-own to c~el Whell compo~nded into animal feedstocks and these yrades are either avoided or have to be used carefully to avoid problems in such applications. Some previous work carried out suggest~
that a particular component of these unusual molasses is acid sensiti~re and yelation occurs as a result, although the mechanism has not been fully explained.
We have found that in the pxesence of phosphoxic acid at particular levels even a molasses considered to be non-gelling can be made to gel. Over a fairly narrow ratio of molasses to phosphoric acid gelation occurs and the viscosity increases at lower levels of addition suggest a ætoichemetric mechanism ie. the phosphoric i acid radicals co~bine in some way with the molasses to ~ form a new "copolymer". However other acids particularly ;~ organic acids are known to exhibit a similar effect. Since wood is acidic it is believed that the acid radicals in ~20 the sawdust cause the hardening due to gellation of log - mixes containing molasses. This wa~ confirmed by addiny a small quantity of sodium carbonate to one of two otherwise similar batches of a log mix containing 35 parts - by weight of sawdust, 20 parts by weight of molasses and 45 parts by weight of molasses. The neutralisation of ; the wood acids by the æodium carbonate was found to result in a marked reduction in the hardness of the mix, confirming that the acidity of the wood contributes to the hardening process. With the pressure of carboxylic acids, amino acids and hydroxyl groups in molasses, and ~, ~
- similar groups in wood, it is likely that the hardening ~` -35-'; ' . .

~L3Z4~il is c-ls a r~sult ol copolymerisation oE molasses in~redients and ~ood colnponcnts to forl~ for example esters, ethers ~r polya!nides~ The acid c3ellinc~ effect can be promoted by addition to the mix oE phosphoric acid or other acid donating chemicals to speed up gellation.
' Whilst the water content of molasses might appear to be undesirable, the water can in fact lead to improved combustion. Papers presented to the wood Energy Institute of Canada in 1978 show that wood burns most efficiently at a moisture content of 12-22%. Normally kiln dried wood is used for synthetic logs, having a moisture content of 6-10% by weight since with higher moisture contents extrusion problems occur as the wood becomes springy.
Additions of 2~/o by weight molasses having 80% by we-iyht active solids to a log mix gives an improved wood moisture content, from the point of vlew of combustion efficiency, ., i,, but the moisture is trapped in the molasses and does not ;~ interfere with the extrusion behaviour of the mixture.

Waste Oils and Used oils-Mineral~ Animal and Vegetable This is a particularly important group since ` not only are used or waste oils cheap usef~l sources of .. ~,~ .
~; heat as a fuel but, with conservation and energy economy . ~, . ..
major current social problems, the non~polluting disposal of such waste products is of major significance.

~ Waste or used oils fall into two groups, mineral `3`~ or non-edible oils and edible oils. Activities where,~ ~
fairly large quantities of used oils accumulate are:-(1) Automotive service stations-used engine oils, transmission oils, etc.

3~

,~
~ .
~; ' . .

1~3Z~

~2) ~estaurclnts and hotels - usecl coo]clng oils.
{3~ ~eavy industry, sheet metal manufacturers, et~. -lubricating or metal surfa~ preparation oils.
(4~ Ship repair harbours - waste ~unkering oils, hydraulic oils and engine oils.
(5) Metal filament industry - oils used during the drawing process in wire manufacture.
(6) Slaughter houses - waste fats and animal oils.
(7) Tanning industry - hide oils produced during curing.
~8) Soap and food manufacture - off colour or contaminated fatty oils, etc.
(9) Paint and varnish manufacture - reject castor oils, varnish oils, etc.
All oils are useful fuels and can be converted into a form suitable for synthetic log manufacture.
~ . .
~ Conversion into an extrudable solid form suitable for , ... . .
loy manufacture can bP achieved in a variety of ways, but all rely on inclusion of the oils into a solid ''''~i`~
j solution. Most organic solids will absorb varying amounts of oils before losing their solid form at room temperature. Particularly useful solids are waxes, fatty : I
;-~ acids and glycerides, rosins, rosin esters, soaps, synthetic polymers such as polystyrene, polybutadienes, . , ` isoprenes, polyolefins, and polybutylenes.
~' For example, waxes can retain up to 30-40~0 by :.:";. 1 .
weight of oils before losing their solid form at room temperature. Blends of waxes are particularly desirable -paraffins of varying melting points up to 160 F. not only retain oils ~particularly mineral types) but can give a quite firm solid at room temperature, as illustrated by the following table:

s:

~32~i R~ined P~raEfi.n/~, used oi]. Texture After Wax Mpt F. Cooli~Z
125 30 Soft Oily Semi solid 155 30 Slurry With oil Separation 50% ~ 125; 50% - 155 30 Fai~ly Firm solid - 25% ~ 125; 25% - 135;
25% - 145; 25% ~ 160 30 Firm Solid The texture of the above blends may be further ;
~nhanced by dissolving in the hot blend small amounts (0.25-2~/o) of other solids such as the following:
- 10 polyethylene, polypropylene, polyvinylp~rrolidone, - polybutylene, polyisoprene, polyisobutylene, polybutadiene, micxocrystalline waxes, and natural waxes such as carnuba or montan.
A particularly efficient group of polymers for - providing solid solutions of oils is the diene polymers.
For e~ample, if a polybutadiene is formed with suitable .
catalysts (lithium aluminium hydride or titanium tetraiodide) to give a high level of transfiguration it will reta-in as much as 96% by weight of oils. The polydiene i9 heated in the oil until dissolved and thoroughly dispersed~
spraying of this solution onto the sawdust followed by cooiing and extrusion gave cohesive logs of good fireplace ~i~ performance. Other polymers may be also dissolved in the hot solution e.g. polyethylene, which acts as a cheaper ` extender for the diene, also gives a more cohesive ~'~,' ' .
structure if added at levels such as to replace 10-50%

~ of the polydiene. Natural rubber or gutta percha, which ;~ are polydienes of high trans configurations, can also be usFd in a similar manner.

~ Solid solutions such as those described in the s~ -3~-::"~
~' ' .. .
,, . . : .... . .

~3246 pr~cedincJ p~racJraoh ccln also be utilized to form satisf~ctoly logs with reduced contents of cellulosic material, or even without cellulosic material, since the polymers will carbonise during combustion 50 as to release the oil and at the same time provide the required porous skc~leton. Gutta percha provides particularly good results under these circumstances.
Edible oils and other animal, fish or vegetable oils can be retained by mineral oil based carrier solids, particularly micro-crystalline waxes at, for example, up to 3~/O by wèight of oil. However, more cohesive and ~irmer solid solutions can be prepared by using non-mineral carrier solids such as carnuba wax, rosins, stearic acid, and linolenic and . ;, ~
linoleic acid salts.
The solid solutions are prepared by dissolving the oil in the carrier solid applying heat if necessary.

, ~eutralisation to form a salt, for example, in the case ; - of oleic or linoleic acid may be carried out in .
~- 20 solution or during preparation of the log mix as ~; described previously. Blends of oleic, linoleic and linolenic acid with up to 4~/O dissolved oil and when suitably neutralised and prepared for log manufacture (mixed with a wicking agent of wood sawdust) make , excellent logs with good burning properties.
,. .
In some cases, even when all the chemical modifications discussed above (eg. neutralisation to minimize coking, acidification to assist degration), the resultant log continues to burn in an unsatisfactory manner. Other modifiers can then be employed to overcome the problem. Typical types of unsatisfactory burning ., - . .
.

~3'24~
take two oppos ite forms: -l) Inad~quate Combustion (S3 owne5s in ~,ighting, Sufoc?tlon or IncomE~ete Co~rbustion~ _ This may be corrected by one or more of the following means:
(a) Inclusion in the solid fuel of small amounts of volatile or low flashpoint mater ials . For example, a log co~prising a fuel of vegetabla and tall oil pitch hardened with sodium oleate gave a log which burned with small flames for an excessively long time. Its burning time ~-could be reduced by the addition to the hot fuel solution 5-15% of fuel oil, kerosene, trioxane or acetic acid. A similar reduction on buring time and increase in flame heiyht was , achieved by adding 5-2~o by weight polyoxyethylene glycol (paraformaldehyde? to the sawdust before . ~ . , - :
addition of the hot fuel solution.
(b) Physical changes in the log shape. For example, - ~ ~ a circular log 2 with a barely adequate burning :~, rate was improved by the foxmation of grooves 4 along its length as shown in Figure lA, either . ~
by cutting or scooping material out of the log a~ter extrusion or by forming projections 6 in ''`Z~i ~ - .
the extruder barrel 8 as shown in Figure lB.
The flames from ignition spread more rapidly along the edges of the grooves and dur ing the .
burn fis~ures developed at the bottom of the ,~ . grooves, allowing faster release of the fuel.
.~ .
;~ This gave more pleasing taller flames and a shorter burning time. An equally good , . ' , . . . . . . . . . ...... . ...
~ .............................. . . - , ~ . .. : . :

324~

~ provem~nt in performa~ce was achieved on a log ~lhich suffered from suffocation problems lincornplete combustion due to coke formation) by formi.ng a hole alony i.ts axi.s as shown in Figure 2A, using an extruder modification as shown in Figure 2B, in which a rod 14 was attached to the extruder screw 16 so as to extend thxough the barrel 1~

(c) Flaws 20 (see Figure 3A) were developed in logs 22 otherwise similar to those discussed unaer (b) . . above by insertion in the extruder forming barrel 20 of short pins or rods 24 close to the end of the barrel as shown in Figure 3B. This gave .: ~
~, high turbulence pressure points in the barrel ;; where they were situated and as a result, during :, the fireplace life of the logs they developed large flaws 20 in the form of cracks at the ~: ~ : location of the pressure points as shown in i .. ~ ' :: Figure A~ Fuel again was able to escape ~ore readily through the cracks giving bright tall ,~. ~ . , ~ . . .
flames and complete-combustion~ Cracking was also successful1y induced using thermally ` expan~ible matexi.als in the mix eg. seeds of .' various descriptions such as rice or corn, encapsulated water, very coarse wood slivers, and expansible polystyrene beads.
, . .
.: .,~
~41-.~'j , . .
;., .~..,~
' .;~,, , ' ' ' , , . ..

4~

((3) ~Suhlivi~ion 0~ the ma~-~rial sho~ing cok;ng t~ndenci~s can l)c acl~ieved by coating pr~sat:urated sawdust with a non-col;inc3 fuel s~cll as wax. For exa~ple, molasses pr~hlel~ded with sawdllst is further coated with wax to ke~p the molasses from forming "coke bridges" across adjacent particles.
(e) A compatible wetting agent may be added to a fuel showing coking tendencies, e.g. nonylphenol 10 mol ethylene oxide in molasses at 0.5-5%, nonylphenol 4-6 mol ethylene oxide in pitches, nonylphenol 3 mol ethylene oxide in asphalt. ~;
~f) Antioxidants may be added to the fuel showing coking tendencies e.g. phenol may be added to pitches, fur-- furyl alcohol or furfuryl aldehyde to molasses.

(2) Bxcessive CombustibilitY (Excessive Flare UP - RaPid Burninq-Excessively Tall Flames) Logs made using used and waste oils trapped in a wax solution initially gave tall flaring flames with a resulting disappointingly short burn time. The burn time was extended by the inclusion in the mix of small ~ ~.
~ 20 amounts of fire retardants e.g. 5-20% sodium phosphate, .
2-8% sodium iodide or chloride, 0.5-7% urea formalde-hyde resin, 2-8% sodium carbonate, 0.5-4% asbestos fibre, 0.5-5% melamine resin, 1-12% dicyandiamide or '' urea.
. .
-~ Whilst synthetic fireplace logs have in the past .~
generally utilized particulate wood, particularly sawdust, : ~ .

~ as a carrier for the fuel component, other particles derived :~
from cellulosic materials may be used. The particles may be ,,,~ .

' . - ~ _ .
1, i ~3;Z~L~
c~ natllral or processed cellulosic materials such as bagasse, cl-oE~pecl straw, waste paper in pulped, shredded or flaked forms, spha~num moss, nut shells, coffee groundsJ
fi~rous residues remaining after the extraction of juices or oils from vegetables and fruit, cotton waste, and bark.
AlternativelyJ particles of regenerated cellulose or cellulose esters may be utilized, or particles of materials derived by total or partial degeneration and mineralization of cellulosic materials such as peat~ lignite and coal.
The state of division of the material should be such as to permit them to act as a carrier and working agent for the fuel component. If the material is in the form of fine fibres or thin webs, then it need not be very finely divided.
Non-cellulosic combustible materials may also be utilised, such as coal dust, though the lack of absorbency of the 1atter may be a problem with certain types of liquid by~product. Soya flour is another combustible material which may be utilised, and which has a high melting point. It is also possible to utilise non-combustible solids to provide the basis of the log skeleton, such a diatomaceous earths, clays or rock wools, although preferably such non-combustible materials should not form too large a proportion of the total weight of the log. Non cellulosic organic fibres may also be utilised, particularly those that will carbonise at high temperatures to provide the desired skeleton.
When non-cellulosic materials such as coal dust are utilised, the coking properties of molasses may be used to advantage. The ash residue left from a log containing a substantial amount of mol~sses after all the volatile fuels are exhausted (flames disappear) i5 a firm cohesive brightly ,. .
.. . .

glowing block shaped ember not unlike a coal ember. Thisel~ber is attractive and prolongs the aesthetically useful life of the log by up to 45 minutes. Normally the ash from synthetic logs has a dull red glow which is at best barely v:isible. A more important advantage of the coking of molasses is that it facilitates the use of non-cellulosic corriers which either will not themselves coke or which will only coke at high temperatures. For example bituminous coal dust, anthracite dust5 carbon dust and graphite powders are useful cheap fuels. However, without a coking binder, such materials crumble too rapidly during burning. ~olasses forms the basis of an excellent coking binder for this purpose and hence a synthetic log based on coal dust or similar material may be produced.
;; Typical formulae comprise:
(1) Coal Dust70 pts by wt Molasses50-35 pts by wt (2) Gas or Oil j;~ Coke Dust70 pts by wt ~-` 20 Molasses45-30 pts by wt These two basic formulae are somewhat soft and the molasses is solidified by the inclusion of slack waxes of the 778 `~ type in place of part of the molasses (up to 50~/O replacement), . ; ~
~`, and/or suitable oil soluble emulsifier (e~. nonyl phenol ethoxylate) may be added at up to 1% to give improved ~ texture. Other heat resistant fuels or polymers may also s ; be used as modifiers, eg. one of the following:
.~
2 - 40 pts lignosulphonate powder 1/2 - 5 pts melamine resin powder '~ 5 - 40 pts pitches of any or all varieties , .~ .
~ ~ 2 - 10 pts mimosa or quebracho rosin powder :. .

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1/2 - 5 pts Polyethylene, polypropylene>
polyvinyl acetate 1/2 - 10 pts Phe~olic resins A solid emulsion can be obtain by using water based polymers, for example the following formùlation gives good results:

Coal Dust 70 pts U
.: 6~/o U~e~ Formaldehyde - ~u~ 3-20 pts res~J
Molasses 15-50 pts Slack Wax 15-0 pts Emulsifier 0.25-1 pts The emulsifier in this case is a water soluble emulsifier eg. sulphosuccinates, benzene sulphonates, naphthalene sulphonates.
Polymerisation of the resin is achieved by addition of conventional acid catalysts eg. phosphoric acid or strong organic acids such as benzene sulphonic acid or paratoluene sulphonic acid. The heat resistance of these mixes can be enhanced by addition of small amounts of melamine, phenol, resorcinol, furfuryl alcohol, furfuraldehyde, or dicyandiamide.
These reinforcinq agents can be usefully employed at levels as low as 2% or as high as 30/0 by weight based on ~he weight . ,~, . .
~ ~ of the urea resin.
.,.
- The cellulosic or other substitute particulate materials w.ill normally form about 35-4~/O by weight of the ~`j log, although contents in the range 25% to 7~/O by weight are , ~....................................... .

possible provided that the combustion properties re~uired of a firelog can be obtained. Moreover, as described elsewhere :. .
in this disclosure, contents down to zero may be utilized provided that components are present capable o~ forming an , . . . .

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aclequate s~eleton during combustion of the lo~.
Rec3ardless of the materials utilised to form the log it is important that whatever constituent of the log mix which is used to solidify the liquid combustible by-product is thoroughly blended therewith, so às to achieve the necessary physical or chemical interaction. This is particularly so when the liquid by-product is solidified by dispersion in another material, or by reason of other material absorbing liquid therefrom.
- 10 The invention is further illustrated by the following tabulated examples of log formulations. The ingredients listed in each example under the heading "Formula"
were thoroughly mixed in the order given7 and extruded into shape o~ a conventional cylindrical log weighing about 3 kg., the combustion behaviour of which was then observed and is noted under the heading "Burn Comments".
In the burning of logs in accordance with the ` various examples, the burn was considered to last from the ~- time that the log was lighted until the flames died out. -~
:7- ~` 20 For a satisfactory burn, the rate of burning should be ;
~ aesthetically satisfactory through substantially the entire .
burn once the log i9 fully allght, ie. a cheerful flame effect should be provided without excessive flaring or flame height suah as to prejudice safety, the duration of the burn should be satisfactory, ideally about three hours, the log ! should substantially retain its shape and dimensions, although some shrinkage will normally occur, and substantially ~ ' the whole of the volatile fuels contained by the log should ,,~ ',~ , ,~ -46- -~ , , -, ~3i 3Z~
h~ conc~lmecl. rhe skeleton formed by most of the log compo~itions described and exempl;fied will be formed largely of car~on, in which a flameless combustion process will often contin~le after cornpletion of the normal burn, resulting in subsequent breakdown of the skeleton into mineral ash.
Ilowever, the log should be formulated so that a-t least 85%
of the total combustible content of the log is consumed during the burn, including at least 95% and preferably at least 9~/O of the volatile combustibles. The above requirements were met by those logs exemplified which were said to achieve a good or improved burn, or to burn well, very comfortably met by those which achieved a very good or excellent burn, and just met by those achieving a fairly good burn. Those logs which suffocated did not burn well, and went out before all the volatile combustibles contained therein were consumed.

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Example Formula Burn Comments -(1) vegetable pitch 60 pts. suffocated due to coking (by weight) improved burn with cocoanut mono- grooves, centre hole or ethanolamine 3 " induced flaw sawdust 20 mesh 37 "
(2) vegetable pitch 60 pts. burned well with little nonylphenol coking, improved with ethoxylate (50 addition of 6 pts. slack EtO) 3 " was sawdust 20 mesh 37 "
(3) vegetable pitch 60 pts. suffocated due to coking hydrogenated improved burn replacing glycerides 6 " 20 mesh with 80-100 mesh sawdust 20 mesh 37 " sawdust or addition of 10 pts. chine clay or addition of 6 parts mine-ral wax or addition of 5 pts. SO~ sodium hydroxide or 6 pts. wax (4) vegetablepitch 60 pts. suffocated due to coking, stearic acid 6 " improved as in (3) and by sawdust 20 mesh 37 " addition of 4 pts. wood rosin (5) vegetable pitch 60 pts. good burn polyglycol ether 3 "
sawdust 20 mesh 37 ., . i: ' (6) vegetable pitch 60 pts. fairly good burn improved refined wax 155F by neutralization with Mpt 5 " caustic soda or as in (1) polyethylene 1 "
sawdust 20 mesh 37 "
:~, ~- (7) vegetable pitch 40 pts. coking, burn improved as sugar 20 " in (1) and~by addition of I wood sawdust 1/2-5 pts. aluminium sul-20 mesh 40 " phate or phthalic anhyd-ride (8) vegetable pitch 60 pts. good burn ` oleic acid 6 "
`~ 50% caustic soda 3 "
or sodium carbonate 3 wood sawdust 20 mesh 37 " -(9) vegetable pitch 60 pts. good burn ~`i polyethylene glycol solid 3 50~ caustic soda 12 ~ wood sawdust 20 ;~j mesh 37 . I

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E~ e~_ormula Burn Comments (lO)tall oil pitch 60 pts. good burn oleic acid 4~ "
50~0 caustic soda 3 wood sawdust 20 mesh 37 "
(:Ll) vegetable or tall oil pitch 60 " fairly good burn wood rosin or some coXing improved by ester thereof 6 " addition of 3 pts. 50%
wood sawdu~t 20 alkali or 6 pts. wax mesh 37 (12) vegetable or tall oil pitch 60 " fairly good burn mixed fatty acids as (11) lolei~, lineolic, linolenic etc.) 6 "
wood sawdust 20 mesh 37 ~' ;, ' ' : (13) 86% molasses 60 " fairly good burn~: polyethylene some coking improved glycol (solid) 6 " by add~tion of aluminium wood sawdust 20 sulp~ate (1-3 pts.), or . mesh 6 pts. wax (14) 86% molasses 60 " as (13) ~:~ rosin or starch 2 : wood sawdust 20 .. ~ mesh 37 "
(lS) 86~ m~ohlasses 60 ~ good burn, slight coking xant~um gum 0~3 " reduced by addition o wooa 20 mesh 40 " 3 pts. slack wax or 3 pts.
nonyl phenol e~hoxylate . . ~
: (16) 86% molasses 60 " a~ (15) ~ ~ alginate 0~3 t ~: wood 20 mesh 40 "
, . (17) refined para~fin , wax 140F Mpt 30 " very good burn .
microcrystalline . 160F Mpt lO "
Iji used engine oil 20 rA~ wood 20 mesh 40 . . (18) pol~butadiene trans form) 6 " ve~y good burn ~: polyethylene ~: used en~ine oil 53 wood 20 mesh 40 ~'' ' ., .
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Ex~p-e Formula Burn com~ents (19) vegetabl~ acid 30 pts. good burn blend (oleic~
linoleic and linolenic) used cooking oil 30 "
Sodium carbonate 6 "
wood 20 mesh 40 "
~ !
(20) crude cocoanut fatty acid 30 " good burn off colour fish oil 25 "
slack wax 5 "
sodium carbonate 5 "
wood 20 mesh 40 "
- ~ (21) tall oil ~ 30 " good burn, some coking ~ :
'-J slack wax 30 " reduced by additional ~ -. wood 20 mesh 40 " 1 part sodium carbonate (22~ tall oil pitch 10 " ~:
: sodium carbonat-e 8 molasses (85%) 20- " - -slack wax 20 " :
nonyl phenol ethoxylate (4 ~ EtO) 1 "
:~ wood 20 mesh40 " very good burn -~
~ 23) tall oil pitch 10 .: sodium carbonate 8 " . ~ .
,` molasses (85%) 20 "
slack wax 20 ~ nonyl phenol :
'''::~! , ethoxylate (4 ;. ~ EtO) 1 " :- ;
bagasse (finely - divided) 40 " very good burn (24) vegetabIe pit~h 30 " : :
sodium carbonate 6 " :~
para~ormaldehyde 5 molasses 30 " . ~-.
wood 20 mesh40 " very good burn (25) molasses .25 -"
slacX wax 30 : finely divided :-~ ~ crushed peanut !'''', ~ ' 'shells 45 u very good burn .

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~32~i ~ am~le l~rrnul.a s~rn comm nts - (26) veg~table pitC~I 60 pts, oleic acicl 6 50~.caustic sod~ 3 coffee yrounds 37 " good burn (27) vegetable pitch 60 poly~thylene glycol solid 3 "
50~/0 caustic soda 12 sawdust 20 mesh 18 shredded waste paper 18 " good burn (28) sawdust 40 " spongy log but good burn molasses . (75% solids)15 "
slacX wax 45 (29) sawdust 10 " firm log, excellent burn -.: molasses - (75% solids)25 "
sawdust 30 "
slack wax 35 "
(30) sawdust 10 " very hard log, excellent : molasses burn (85% solids)25 :~ 5 awdust 30 ~:~ slack wax35 "
;. , .
.. (31) sawdust 10 " hard log, excellent burn 85% molasses 20 ' . } pre mixed ~ : :
~`` saw~ st 30 slack wax 35 (32~ sawdust 10 " firm log, good burn molasses (75%)30 "
85% phosphoric -mixed in stream : : acid 3 " -sawdust 30 ` sl~ck wax 30 : (33) vegetable pitch 60 nonyl phen~l ~: ethoxylate (SO
EtO) 3 .
~.~ ` coal dust 37 " good burn ,~ "

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Claims (45)

1. THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
   PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
   
   l. A synthetic firelog comprising a log shaped extruded mass of material of sufficient dimensional stabi-lity to hold its shape at normal room temperatures, and carbonizable on combustion to provide a porous skeleton which will substantially maintain the configuration of the log, the material comprising a mixture of 25% to 70% by weight of particles of solid combustible material, the balance consisting essentially of a combustible solid bin der, the binder consisting of at least about 15% by weight of the log of at least one normally liquid combustible by-product, and a further component interacting with said liquid combustible by-product to solidify the latter and form said binder, the combustibility of the extruded mass being such as to provide a safe but aesthetically accep-table rate of burning under firegrate conditions from the time the log is fully alight until substantial consumption of the volatilizable content of the log.
2. 2. A firelog according to Claim 1, wherein the combustibility of the log during its burning is controlled by shaping of the latter.
3. 3. A firelog according to Claim 2, wherein the surface of the log is grooved.
4. 4. A firelog according to Claim 2, wherein the log is extruded with at least one hole therethrough.
5. 5. A firelog according to Claim 1, wherein the combustibility of the log is controlled by the formation of deliberate flaws in the extruded mass.
6. 6. A firelog according to Claim 1, including agents selected to induce flaws in the extruded mass during combustion.
7. 7. A firelog according to Claim 1, wherein the character and size of the particles are selected to control the degree of coking of the extruded mass during combustion so as to maintain the structure of the mass without smothering combustion.
8. 8. A firelog according to claim 1, incorporating a combustion accelerating additive.
9. 9. A firelog according to claim 1, incorporating a combustion retarding additive.
10. 10. A firelog according to claim 1, wherein the liquid combustible by-product is in solid solution in the further component.
11. 11. A firelog according to claim 10, in which the further component is a wax.
12. 12. A firelog according to claim 11, in which the wax is a mixture of waxes of different melting points.
13. 13. A firelog according to claim 1, wherein the further component interacts chemically with the liquid combustible by-product to solidify the latter.
14. 14. A firelog according to claim 13, wherein the further component interacts chemically with the by-product.
15. 15. A firelog according to claim 14, wherein the further component at least partially neutralizes acid components of the by-product.
16. 16. A firelog according to claim 13, wherein the further component acts to gel the liquid combustible by-product.
17. 17. A firelog according to claim 1, wherein the liquid combustible by-product is selected from the group consisting of vegetable or tall oil pitches, mineral pitches, asphalts, coal tar pitches and creosote residues.
18. 18. A firelog according to claim 17, wherein the further component comprises an effective amount of a gelling agent selected from the group consisting of solid fatty acids, fatty acid salts, petroleum waxes, natural waxes, wood resins, modified resins, synthetic polymers known as gelling agents, surfactants, solid hydrocarbons, saccharides and polysaccharides and their acid salts, and solid fats.
19. 19. A firelog according to claim 17, wherein the further component comprises an alkali.
20. 20. A firelog according to claim 17, wherein the further component comprises a substance which copolymerizes with the pitch acids to form solids.
21. 21. A firelog according to claim 17, wherein the further component comprises an oxidizing agent.
22. 22. A firelog according to claim 1, wherein the liquid combustible by-product comprises a sulphite lye.
23. 23. A firelog according to claim 1, wherein the liquid combustible by-product comprises molasses.
24. 24. A firelog according to claim 23, wherein the further component comprises a water soluble gelling agent.
25. 25. A firelog according to claim 23, wherein the further component comprises lecithin pitch.
26. 26. A firelog according to Claim 23, wherein the further component comprises a wax.
27. 27. A firelog according to Claim 1, wherein the liquid combustible by-product comprises an animal, vege-table or mineral oil.
28. 28. A firelog according to Claim 27, wherein the further component holds the oil in solid solution.
29. 29. A firelog according to Claim 28, wherein the solid solvent is from the group consisting of waxes, fatty acids, fatty acid glycerides, rosins, rosin esters and soaps.
30. 30. A firelog according to Claim 28, wherein the further component is a diene polymer of high trans configu-ration.
31. 31. A firelog according to Claim 1, 17 or 23, wherein the solid combustible material is cellulosic material.
32. 32. A firelog according to Claim 1, 17 or 23, wherein the solid combustible material is a comminuted material selected from the group comprising wood, bagasse, straw, shredded, flaked and pulped paper, sphagnum moss, nut shells, coffee grounds, fibrous residues from the extrac-tion of juices or oils from fruit and vegetables, cotton waste, rayon waste, bark and peat.
33. 33. A synthetic firelog comprising a log-shaped extruded mass of a material of sufficient dimensional stability to hold its shape at normal room temperatures and including 25% to 70%
    by weight of solid particulate combustible material, the extruded material consisting essentially of a mixture of a first component consisting of solid particulate combustible material, a second component consisting of at least one liquid combustible by-product forming at least 15% by weight of the mixture, and a third component including any balance of the solid particulate combustible material and intereacted with the second component to render the latter a solid which in admixture with the first component acts as a binder to produce a substance having a degree of plas-ticity and thixotropy such as to render it extrudable under the influence of heat and pressure, the log having a com-bustibility providing a safe but aesthetically acceptable rate of burning under firegrate conditions from the time when the log is fully alight until its volatizable combus-tible content is substantially exhausted, and the log material being such as to leave during burning a skeleton which substantially maintains the shape and dimensions of the log whilst being sufficiently porous to avoid smothe-ring the combustion of volatile constituents of the log as its burning proceeds.
34. 34. A firelog according to Claim 33, wherein the solid combustible material is particulate cellulosic mate-rial which carbonizes during burning to form the skeleton.
35. 35. A firelog according to Claim 34, wherein the log comprises about 35% - 40% by weight of particulate cellu-losic material.
36. 36. A firelog according to Claim 33, wherein the liquid combustible by-product is selected to form on combus-tion a coke which contributes to formation of the skeleton.
37. 37. A firelog according to Claim 33, wherein the solid particulate material comprises a non-cellulosic mate-rial which contributes to formation of the skeleton during combustion of the log.
38. 38. A firelog according to Claim 37, wherein the non-cellulosic material is powdered coal.
39. 39. A firelog according to Claim 34, wherein the cellulosic material is moisture absorbent, and the liquid combustible by-product is selected to be reduced to an ex-trudable solid by the withdrawal of moisture therefrom.
40. 40. A firelog according to Claim 39, wherein the liquid combustible by-product is molasses.
41. 41. A firelog according to Claim 34, wherein the second component includes at least 15% by weight of the log of molasses.
42. 42. A firelog according to Claim 41, wherein the third component comprises a water absorbent cellulosic material.
43. 43. A firelog according to Claim 42, wherein the first and third components are separate additions of wood particles.
44. 44. A synthetic firelog comprises an extruded mass of a material of sufficient dimensional stability to hold its shape at normal room temperatures, and carboni-zable on combustion to provide a porous skeleton which will substantially maintain the configuration of the log, the material consisting essentially of at least 25% by weight of particulate solid combustible material and a combustible solid binder, the binder comprising a major proportion by weight of the log of at least one normally liquid combus-tible by-product modified by the presence of fatty acid salts in a quantity sufficient to solidify the binder, the combustibility of the extruded mass being such as to pro-vide a safe but aesthetically acceptable rate of burning under firegrate conditions from the time the log is fully alight until substantial consumption of the volatilizable content of the log.
45. 45. A firelog according to Claim 44, wherein the by-product contains fatty acids, and the fatty acid salts are produced at least in part by the neutralization of said fatty acids present in the by-product.