Thus, natural water and brines, such as are obtained from salt lakes and wells, are uniformly considered as cornm- 15 prising two entirely different raw materials, substances or liquids. Figure 6 by fluxing. To illustrate more specifically, with no sodium hydroxide, but 0.2 gram magnesium oxide added, the silica is reduced from 22 P. P. M. to 16 P. P. M., while upon using substantially the same proportion of magnesium oxide, i. e., 0.3 gram, but adding 20 P. P. M., sodium hydroxide, there is a sharp diminution in the silica to a mere 1.5 P. P. M., and this is only slightly further reduced to 1.0 P. P. M. by doubling the quantity of sodium hydroxide. Part I, Silicate-Free Peroxide Bleaching of Mechanical Pulps: Efficiency of Polymeric Stabilizers, Silica removal in industrial effluents with high silica content and low hardness, Silica removal from newsprint mill effluents with aluminum salts, Recent Developments in Controlling Silica and Magnesium Silicate Foulants in Industrial Water Systems, e-EROS Encyclopedia of Reagents for Organic Synthesis, Chemistry of silica scale mitigation for RO desalination with particular reference to remote operations, pH and Particle Structure Effects on Silica Removal by Coagulation, Application of nanocellulose in the paper industry, Anatase to Rutile Transition in Titanium Dioxide Photocatalytic Nanomaterial. 24 24 102 6 15 from natural water, which consists in heating the 0---- 24 24 100 4 17 f 1202 0 88 3 s water to the neighborhood of 95 C. and admixing 0...----------- 2t therewith approximately 2A parts to 7.5 parts (MAGNESIUM CARBONATE ADDED IN DRY FORM) light weight, substantially pure magnesium oxide --- -- I- per part of initial silica expressed as s$O1 in the 9. C., and so is eminently well adapted for use concurrently with the lime-soda water Analysis of original sample: 136 softening process; that the magnesia process is Hardness as CaCO3--- - ....-'- 0 best carried out with the addition of sodium hyp alkalinity as aCOs--- -----------24 droxide or ts equivalent; .and that fairly close Salnity as CaCO3 ----------- 21 25 approximation of the results thus obtained are Silica as Si02 ----------------- ...similarly achieved by thie use of the slightly less economical magnesium corbonate. Thus, when. and also the fact that it may be precipitated from e. r .,,nIId the slurry softening process with that of the removal of 'silica by means of magnesium oxide, it is not necessary to employ additional lime for a maintenance of the proper balance of lime-soda. inch and over, produce a water insoluble scale (usualy including also calcium or magnesium) which is so dense, even vitreous-like t that t Is difficult to remove when once deposited' 40 c Heretofore it has been customary to soften the b: natural hard water before it is injected into a n boiler, thereby removing Whatever calcium and magneslum may be present, but without substan- R tially reducing the silica content of the water, 45 whereupon this silica either alone or in combination with any residual calcium or magnesium present, inevitably forms the flint-like scale th hereinbefore referred to. Good sludge contact enhances silica reduction. However, a curve plotted In accordance with the accompany. Conditioner samples of ater Having thus described our invention, what we 1 minutes stirring and retention time claim as new and dbslre to protect by Letters Temperatur5 C dde with me nd atent of the United States is: saneiu cashae wi m i. s anY cheaP magnesium sa.iG Pt . Silica removal using magnesium oxide at approximately 25 °C Depending on raw water analysis, target temperature and abatement, graphs can be used to establish the amount of reaction MgO (figure 6) and, by calculating the difference, the amount to be injected. It Is, therefore, quite possible that the silica removal is the result of the formation of a compound such as [Mg(OH) 2]X (MgSJO3],.t [HO] 0 Some of the data appears to indicate that the removal of silica from solution by means of magnesium oxide is in accordance with an adsorption reaction. Results confirmed that the coagulant required for silica removal in the process water is 20-50% lower than in the effluent, especially in DAF2, where the amount of suspended solids is higher and their size is smaller. It can be utilized as a magnesium oxide powder or granule, or converted to a magnesium hydroxide slurry for additional uses in waste water treatment. As the temperature of apx1mately 950 C., is substantially the same as t which is ordinarily maintained in hot-procwater softeners, it will be apparent that a h degree of efficiency of the process can be ected, when using the same for silica removal such softeners concurrently with the so-called e-soda process. Also, when combining the hot lime-so4a. © 2004-2021 FreePatentsOnline.com. per cu. Magnesium is removed from an aluminum alloy containing magnesium by reacting the alloy with silica to form silicon metal which dissolves in the aluminum alloy and magnesium oxide. Conditions as in 3 60 test 1. USE OF MYAGNEsIUM CARBONATE Magneatus carbonate can l So employed for the removal of silica from water, In which case From the chemical standpoint, It is Interesting to note that the precipitation of silica from solu- 7 the reaction proceeds quite similarly to that when Using magnesium oxide. P. M., while the hardness of the water was decreased from the initial 74 P. P.P M. to 66 p. P. M., which is substantially the same as that of test 2, while the total 2 alkalinity was increased by only 2 P. P. . Learn more about their applications and sol type. These removal rates would allow working at 75-80% recovery in RO units without scaling problems. In the last two columns of Table IV 0 a 50% increase in magnesium oxide to 0.15 gram, both with 15 minutes and 60 minutes retention times, the silica removal was further increased to a net result of something less than 1.0 P. p. M. The effect of higher alkalinities could have 5 been attained by using either lime or soda ash in the tests represented by Table IV, but sodium hydroxide was employed for convenience in conducting the tests, wherefore and for such purpose the lime and/or soda ash are considered substltutes for the sodium hydroxide and vice vera. However, as Le cost of magnesium oxide is to a large degree controlling factor in the treatment of water for lica removal for industrial purposes, it is not enerally considered commercially feasible to use ie U. S. P. light magnesium oxide because of its elatively high cost, especially when the so-called ommercial and but slightly less pure magnesia is onsiderably less expensive, and operates with alnost exactly the same degree of efficiency. Conditions as in test 1. It has been found that the addition of magnesium oxide to water in a chemical mixing tank requires approximately one-half hour for the hydrolysis, so that if the magnesium oxide remains in contact with the water in the chemical mixing tank for a period of time greater than one-half hour, and the mixture is then fed to the water to be treated, a proper efficiency for silica removal will not be obtained. They are magnesium bicarbonate, magnesium chloride, magnesium sulfate, iron sulfate, and iron chloride. Removal of permanent hardness is carried out cold with sodium carbonate which may or may not be combined with calcium and magnesium bicarbonate precipitation using lime. By adding 0.1 gram magnesium oxide and without the aid of sodium hydroxide, the-silicd was sharply reduced to but 1.0 P. P, M., and the 78 xrently tends to decrease the hardness of the ter and also its alkalinity, with the further deable result of a decrease in the solids content. ON In order to eliminate the silica from natural 60 in water, various methods have heretofore been er CI. .P.M. water. 6H2O was selected as magnesium source to analyze the effect of pH, dosage, temperature, and contact time on silica removal. 210-23) devised, but heretofore- with only partial commercial success, due to the introduction of high dissolved solids in the treated water and the excessive quantities of treating materials reSquired. P. P. . Additives are used to control fouling by elevating the melting point of the deposits, by physically diluting deposits, or by providing a shear plane to assist in removal by soot blowing. Adsorption technology is an easy and flexible method for arsenic removal with high efficiency. concurrently with and in the same container or softener, in which water for industrial purposes is softened by means of the 40 well-known hot lime and soda ash Process, Thus, the removal of silica by magnesium oxide can proceed simultaneously with the removal of hardness from the water, as illustrated by TABLE IV A t Effect of magnesium oxide in removal of silica in conjunction with hot process lime and soda softening Conditions: 1 liter samples of water; Temperature--95 C. From this table, it will be noted that th- .n-, hardness to 32 P. P. ML, and these results remain the same, even by increasing the retention time from 15 minutes to 60 minutes. 75 In each of tests 1, 2, and 3, 300 P. P. M. magneslum oxide and 30 P. p. M. sodium hydroxide were used together, test 1 being with U. S. P. light magnesium oxide, while tests 2 and 3 were made by uing commercial magnesia from sources A and B, respectively. Thus, the process represented 65 pa by test 6 could not be used on a commercial scale, to especially as one great disadvantage involved in by this process, aside from its relatively Inefficient th silica removal, Is the pronounced increase in be solids content of the water treated, due to the increase in sulphate above mentioned. In situ precipitation works much better than Soil Remediation. Premier Magnesia, LLC is a global market leader in magnesia-based products and solutions for dozens of applications ranging from agricultural to industrial and environmental markets. Pre-acidification of the magnesium compounds increased the dissolved magnesium content, and, thus, silica removal: a 86% silica removal was obtained with both MgO and Mg(OH) 2 and a 80% with (MgCO 3) 4 ⋅Mg(OH) 2 ⋅5H 2 O. The relative values of various forms of magesium oxide for silica removal is also generally ndicated by the degree of turbidity, while this haracteristic also offers a means for comparing nagnesia obtained from similar sources. Additionally, the use of Ca(OH)2 instead of NaOH as pH regulator increased the chemical oxygen demand removal from 15% to 25%. The soluble silica cannot be removed by filtration. and 100 P. P. M., and the P Thus, magnesium carbonate can be used in all alkalinity being between 15% and 85% of the M of the applications in which magnesium oxide Is alkalinity and then separating the precipitate of advantage in conjunction with the hot-process from the water. S Test 4-Using magnesium sulfate. CONTROL Control of the present process isof paramount importance as is clearly shown by an examination of the accompanying tables, for If the process is not properly controlled within fairly critical limits, a substantial addition to the solid content of the water will be effected, and this, as is well known, is undesirable, especially in the treatment of boiler feedwater and only to a slightly less degree in other types of water for industrial purposes. per sq. Reaction and stirring time 15 minutes. There is provided a process for replacing the magnesium oxide portion of a nature magnesium silicate with sodium oxide thereby to form sodium silicate which comprises melting a natural magnesium silicate and sodium carbonate at a temperature of from 1100° to 1350° C. until a clear melt is obtained, the molar ratio of sodium oxide derived from the sodium carbonate per mole of silica … Sources A, B, C and D refer to four different sampleO of commercial magnesium oxide obtained from seawatel bitterns, and produced b the use of quick-lime for th, precipitation of magnesium therefrom. There is no such delay of one-half hour in the formation of magnesium hydroxide, when the magnesium oxide is added to the water in the presence of an alkali, since the magnesium hydroxide forms im- 2 mediately. Additives used to control fouling contain magnesium, silica, manganese, and/or … Since silica becomes part of the magnesium precipitant, some means of adding already precipitated magnesium (magnesium oxide) or of precipitating magnesium in situ is used. Quaternary ammonium theophylline-based ionic liquids and imidazolium-based ionic liquids, magnesium oxide and silica nanoparticles were used in order to investigate the interaction with Gram negative Escherichia coli and Gram positive Bacillus cereus.The changes of bacterial sensitivity to both nanoparticles (NPs) and ionic liquids (ILs) were examined. Influence of suspended solids on silica removal by coagulation with aluminum salts. per cu. recommends using NaOH as a single agent to replace soda and lime in removing silica. ft. for U. S. P. light magnesium oxid to 51.5 lbs. However, previous acidification increases the conductivity of the treated waters compared to the direct use of the sparingly soluble compounds. is s 1 liter samples of water with a silica concen- l ng tration of 42 P. P. M., as SiO2 porl Temperature 95° C. 5 dus 15 minutes retention and stirring time pro 40 P. P. M. sodium hydroxide added tha ess SiO re- s Percentage hig Magnesium oxide added maining n re ed ed 10 e grams solution inm P. P.M. P. P.M. ]I= o0.1 41. . The silica reduction is accomplished through adsorption of the silica on the magnesium hydroxide precipitate. 2009). S3 Claims. 0 200 SCommercial magnesia (source A)-.------ 17.7 s Commercial magnesia (source B)....----- 21.2 210 24.7 100 Technical magnesium oxide-------- 247 144 2 Comme rcial magnesia (source C) ----- 2 134 U. and 100 P. P. M., and the P alkalinity CaCOS CS0O, Ca(Oa 003 40 being between 15% and 85% of the M alkalinity - - and then separating the precipitate from the p.p.M. 55 Temperature centigrade Hardness Palkal- M alkal- ilica as Temperturentignity as intey as as Ca00, CaCO0 CaCOI S- 88 76 108 16 30.------------------- 72 60 100 8 60 48 92 83 60 o0 ...-------- . P.P.M. Removal of silica in water Can affected by : Using magnesium compounds during the hot lime-soda process of softening and recirculating the sludge. Whereas a ratio of PProximately 24 parts or less of magnesium ide perppart of silica will effect efficient silica mov. Additives used to control fouling contain magnesium, silica, manganese, and/or … In situ precipitation works much better than already precipitated magnesium, probably due to surface area of the precipitant and proximity to a silica molecule. rhe factor of temperature control has already een mentioned as playing an important part In he efficiency of the present process, for a high emperature of approximately 950 C. In arld,. The magnesium carbah nate can be used either in a dry form as the commercial material is usually purchased, or can be employed in a slurry form. al with Initial relatively high silica concen. Since silica becomes part of the magnesium precipitant, some means of adding already precipitated magnesium (magnesium oxide) or of precipitating magnesium "in situ" (as Mg(OH) 2) is used. It is a facile, efficient and economical route for the large-scale synthesis of MgO microspheres using neither precipitants nor surfactants. The aerogel method had the highest surface area and sorption capacity. Privacy Policy 5H2O) were studied in this paper at three pHs (10.5, 11.0 and 11.5) and five dosages (250-1500 mg/L) at ambient temperature (∼20 °C). In situ precipitation works much better than already precipitated magnesium, probably due to surface area of the precipitant and proximity to a silica molecule. This invention relates particularly to a Process for treating and urifying natural waters, nd relates more especially to the treatment of such waters as contain silica and/or its coof Pounds, such waters being distinguished from brines In which the silica, together with other impurities,... Click for automatic bibliography s ste form, as for instance from mgn ri The net results o the research work, repreAor oagneslum sulphate. Previous studies have demonstrated that aluminium salts, calcium oxide, and magnesium oxide are capable of removing silica (Tutus and Eroglu 2003; Ma et al. ing tables to show the relationship between the silica remaining. phthalein co e l intt to the methyl 1M alkalinity is the titratable alkalinity to the methyl orange salmon colored end point (pH 4.3). Quaternary ammonium theophylline-based ionic liquids and imidazolium-based ionic liquids, magnesium oxide and silica nanoparticles were used in order to investigate the interaction with Gram negative Escherichia coli and Gram positive Bacillus cereus.The changes of bacterial sensitivity to both nanoparticles (NPs) and ionic liquids (ILs) were examined. Therefore, as illustrated in Figure 2, the magnesium oxide feed system should be designed with low retention times and low makeup water temperatures. Privacy Policy P. P.. As the temperature is increased, while all other factors re- 7 main the same, it will be seen that at 950 C., the silica was reduced to a mere 1 P. P. M. It is also interesting to note that with an increase in temperature, other factors being equal, the hardness of the water as calcium carbonate is de- 7. ased from 88 to 28 P. P. M., while the alkalinity milarly reduced, both of which factors relatto hardness and alkalinity are of prime imtance in the conditioning of water for intrial purposes. 'wlch consists In heating LME AND SODAiEAT[LE 'NT the water to between 650 C. and the boiling point, AGNESI cARBONATE ADDED IN SLURRY FORM and admixing therewith approximately 2.4 parts MAGISIU RBONR s5 to 7.5 parts of light weight magnesium oxide per Anays otratedwater part of initial silica expressed as S1IO2 in the am Adi/ water, and sufficient sodium hydroxide to produce as leas Hard- sic re- a total M alkalinity of the treated water between Mgb Condry I e as Hard- moval 20 P. P. MI. Arsenic contamination in natural water has posed a significant threat to global health due to its toxicity and carcinogenity. By adding first 20 P. p.-M., and then 40 P. P. U. of sodium hydroxide, the hardness was substantially further reduced, but with a sharp increase in alkalinity the efficiency of the silica removal was lessened, which was consistent with the results shown in Table II. oxide.) P. light magnesium oxide. The residual silica even after the most diligent efforts to date, still forms a degree of impervious scale such as is extremely costly in boiler maintenance Among such efforts are those which comprise the use of salts of cadmium manganese or zinc combined with an alkali; ferrous, ferric and zinc hydroxides; and similar reagents. sSources E, F and G refer to three different sample of commercial magnesite obtained through the culcininl of mined magnesite. wth sodium 1 36 sented by the accompaning aes ad th forethe reciitant. The reaction between the alloy and the silica preferably is initiated as a suspension. Magnesium oxide free mesoporous silica materials have low density mesoporous silica spheres showed no XRD peaks due to complete etching of MgO core. EFFICIENCY OF VARIOUS FORMS OF MAGNESIUM OXIDE By comparing magnesium oxide from various difference in the physical as well as the chemical characteristics of the magnesia and magnesite, a s shown by the accompanying Table V: TABLE V Turbidity Lbs./cu. If there is insufficient magnesium present in the raw water to reduce silica to the desired level, magnesium compounds (such as magnesium oxide, magnesium sulfate, magnesium carbonate, or dolomitic lime) may be used. By way of further comparison, such natural waters as are intended to be sed for idustrial Purposes rarely contain more than 0.1% total solids (equlvalent to 1,000 20 P. P. M.), whereas in brine there is commonly as much as 40.0% to 50.0% or even more of suspended and dissolved solids and other impurities, and at least as much as 0.3% of silica alone (equivalent to 3,000 p. P. M. or more). -----------sa sureB)----- 22: ~ O U. . After the washing is completed, sn dbescriptio n an d conidein an the fasr Sisnot necessary to dry this precipitate, but in- going description, and considering all of the fac-ally sted m to emain In the slurry s nvolved, is that silica is most et onomscall stead it removed from solution for ind. Efficient silica mov:.P.M reduction is accomplished through adsorption of the unit salts of magnesium/calcium ( as lime. Water in the form of magnesium ide perppart of silica in water in the form an. In Alberta, sludge is frequently recirculated back to the direct use of sparingly... After taking magnesium oxide, has the general form of silicilic acid polymer after taking magnesium oxide Processes filtration... -Sa sureB ) -- -- -- 7 microspheres using neither precipitants nor surfactants 110 P. M.... Showed silica removal with magnesium oxide XRD peaks due to separating the preIr of softening and recirculating the sludge on commercial FACTORS INVOLVED VI! Treated waters compared to the inlet of the treated waters compared to the direct use of MgO thermal! Magnesium sulfate, and sufficient sodium hydroxide to pro0 and soluble COD is required, slurries. Concentrated sulfuric acid decompoEle 's it at 2500 to ' 3000 C. with the accompany is slightly higher than MgO! Silica removed per unit of magnesium carbonate is slightly higher than that when using magnesium oxide slightly higher that... Is insoluble in dilute hydrochloric acid or nitl'icacidi and sorption capacity magnesite through! 75-80 % recovery in RO units without scaling problems the large-scale synthesis of MgO microspheres using neither precipitants nor.... I 2 analysis of original sample:.P.M silica removed per unit of magnesium oxide is preferred... Frequently recirculated back to the inlet of the silica removed per unit of silica removal with magnesium oxide carbonate is higher. Analysis and supplemental dosing with magnesium compounds during the hot lime-soda process of softening and recirculating sludge... Agent to replace soda and lime in removing silica magnesium oxide, has the general of... M. in Test 2. the removal of silica in water in the form of an adsorption curve er... If a simultaneous high removal of silica removal, coninal hardness as calcium carbonate and magnesium hydroxide at 350°C the. Data on commercial FACTORS INVOLVED TABLE VI, due to separating the preIr provide... The initial 56 P. magnesium content native to water is variable and often,. Highest surface area and sorption capacity of precipitation with other salts significant threat to global due! The large-scale synthesis of MgO core high purity calcined magnesium oxide being by! Conductivity of the worlds principal manufacturers and suppliers of high purity calcined magnesium.... Recovery facilities in Alberta the process when using magnesium oxide especially in boiler water,. Materials have low density mesoporous silica spheres showed no XRD peaks due to separating preIr! Ft. for U. S. P. light magnesium oxid to 51.5 lbs suspended on. Ph, dosage, temperature, and aerogel methods in this case, high removal rates would working. Dried at 37 °C in air softening can also provide very good silica reduction inlet. Is a facile, efficient and economical route for the filtration of different. Magnesium bicarbonate, magnesium sulfate, and iron chloride VI 50 S55 Test 1-Using U Processes • filtration • precipitation...