Lignosulfonates Additives

Corrosion control is a greater concern in water-based fluids than in oil-based fluids. As could be observed in Table 18.3, the primary corrosion effects were seen in the water-based muds with the lignite/lignosulfonate additives, while significant levels of slight corrosion were noted in the non-dispersed system. Since these two systems are being used in the industry for reasons not related to corrosion, special efforts must be made to make the systems more corrosion-resistant. 

Hubei Aging Chemical Company China Lignosulfonates Additives for concrete admixtures, feed, leather reinforcing agents for refractory material asnd ceramics Dispersants for fertilizers, pesticides... 

At a constant w/c, the addition of commercial lignosulfonate results in lower strength cement mortars, but later strengths are higher, as can be seen in Fig. Sometimes lignosulfonate addition may not cause an increase in strength at later ages due to the entrainment of air. 

Young, J. F., Hydration of Tricalcium Aluminate with Lignosulfonate Additives,A/ag. Concr. Res., 14 137-142 (1962)... 

Plasticizing agents, e.g., alkyl aryl sulfonates, secondary alkyl sulfates, or their sodium salts, are used to overcome the harshness of many CAC concrete mixes.Workability can be improved with calcium lignosulfonate addition larger doses, however, promote excessive... 

Many of the chemical reactions used to modify lignosulfonates are also used to modify kraft lignins. These include ozonation, alkaline—air oxidation, condensation with formaldehyde and carboxylation with chloroacetic acid (100), and epoxysuccinate (101). In addition, cationic kraft lignins can be prepared by reaction with glycidjiamine (102). 

Lignosulfonate has been reported to increase foam stabihty and function as a sacrificial adsorption agent (175). Addition of sodium carbonate or sodium bicarbonate to the surfactant solution reduces surfactant adsorption by increasing the aqueous-phase pH (176). 

A modified saturated saltwater mud is prepared with bentonite clay by a special technique. First, bentonite is hydrated in freshwater, then treated with lignosulfonate and caustic soda. This premix is then mixed with saltwater (one-part premix to three-part saltwater). The mixture builds up a satisfactory viscosity and develops filtration control. Thinning of the mud is accomplished by saltwater dilutions additional premix is required for viscosity and water loss control. 

Heavy metals are present in drilled formation solids and in naturally occurring materials used as mud additives. The latter include barite, bentonite, lignite, and mica (sometimes used to stop mud losses downhole). There are background levels of heavy metals in trees that carry through into lignosulfonate made from them. 

Calcium-sodium lignosulfonate is a better retarding additive when high concentrations of bentonite are to be used in the design of the cement slurry. 

The use of the lignin fraction is much more cumbersome currently the best-known chemical of a real commercial importance is vanillin, which is obtained by oxidation of the black liquor. Another example is a product called spray-dried lignosulfonate (as sodium salt) obtained from the older, acidic sulfite pulping process. It is sold as a commercial product primarily as a concrete additive for enhanced strength. Since the cement industry is one of the big contributors of carbon dioxide emissions (due to the production of calcium oxide from calcium carbonate), the use of this renewable, wood-derived product not only is fossil-carbon neutral in itself but also reduces carbon dioxide emission due to the diminished need for cement in large infrastructures made of concrete. 

Laboratory experiments have been conducted with a chromium lignite-chromium lignosulfonate mud system both without and with solid lubricants. These studies include filtration loss, cake quality, and their impact on the formation. A comparative evaluation has led to the conclusion that Gilsonite is a better additive compared with sulfonated asphalt as it results in less filtration... 

Examples of retarders are shown in Table 10-11. They are added to prevent cement from setting too rapidly. These additives are also referred to as set retarders. Cements with retarders to prevent rapid setting may be used at the high-temperature and high-pressure environments of deep wells. Common retarders are lignosulfonate and certain carbohydrate derivatives, such as welan gum, xanthan gum, cellulose, and polyanionic cellulose. 

A mixture of lignosulfonates, alkali-treated brown coal, and minor amounts of organic silicon compounds (e.g., ethyl silicone) reduces the permeability of cements [1019]. The additives may interact with the crystallization centers of the cement slurry and form a gel system in its pores and capillaries, thus reducing the permeability of the cement and increasing its isolating capability. Furthermore, it is claimed that the additive retards the setting rate of cement up to 200° C and increases the resistance to corrosive media. 

Acid flooding can be successful in formations that are dissolvable in the particular acid mixture, thus opening the pores. Hydrochloric acid is common, in a concentration of 6% to 30%, sometimes also with hydrofluoric acid and surfactants added (e.g., isononylphenol) [130,723]. The acidic environment has still another effect on surfactants. It converts the sulfonates into sulfonic acid, which has a lower interfacial tension with oil. Therefore a higher oil forcing-out efficiency than from neutral aqueous solution of sulfonates is obtained. Cyclic injection can be applied [4,494], and sulfuric acid has been described for acid treatment [25,26,1535]. Injecting additional aqueous lignosulfonate increases the efficiency of a sulfuric acid treatment [1798]. 

Stabilizing agents are used to maintain drilling fluid rheological properties at highly elevated downhole temperatures. Chromium and chromium-free lignosulfonates, polyglycol ethers, sodium polystyrene sulfonate-co-maleic anhydride), and a melanin polymer have been used in this application. Additives such as sodium diethyldi-thiocarbamate have been used to stabilize aqueous polysaccharides such as xanthan gum (18). 

Lignosulfonates and lignosulfonate derivatives are used extensively as cement set time retarders (20, 21). Many of the same additives used in drilling muds are used in cement slurries and spacer fluids for similar purposes. 

An example of some of the newer regulations is the restriction against the use of the popular mud dispersant, chrome lignosulfonate. It is expected that this regulation is merely the initial step toward ruling out the use of all heavy metal salts commonly employed in the formulation of well fluids because of their toxicity to aquatic life and humans. This means that the use of zinc and lead, in addition to chromium, may not be allowed in the future. At least one major oil company has already taken steps in this direction by ruling out the use of heavy metal salts in any well fluid in their worldwide operations. 

Air-entraining water-reducing admixtures containing lignosulfonates can be based on impure lignosulfonate raw materials, as stated earlier, where only 2-3% additional air is required. However, this air may not be of the amount, type, and stability required, therefore additions of surfactants are made. Several different types can be used but in the majority of cases they are based on alkyl-aryl sulfonates (e. g. sodium dodecyl benzene sulfonate) or fatty-acid soaps (e.g. the sodium salt of tail-oil fatty acids). Additions of these types will allow incorporation of sufficient stable air of the correct bubble size to meet durability requirements under freeze-thaw conditions. 

Water-reducing admixtures are not adsorbed equally by the various anhydrous and hydrated cement constituents and in studies with calcium lignosulfonate, the approximate maximum adsorption figures shown in Table 1.5 have been obtained [38,39], In addition, adsorption isotherms have been studied at various ages of C3A hydration [36] and it has been shown that it is the initial hydration products (less... 

In the absence of knowledge of the surface area of cement hydrates available for adsorption at the time of addition, it is difficult to estimate how many layers of water-reducing admixture molecules are adsorbed, but attempts have been made [40] indicating that over 100 layers may be formed with calcium lignosulfonate and salicylic acid at normal levels of addition. However, these calculations were based on specific surface areas of 0.3-1.0 m g-l, whereas other studies [27, 38, 39] have indicated... 

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