You can sign in here. NaOH boric acid deionised water Hazards: Caustic, can cause severe burns or damage eyes Possible acute or chronic health damage if inhaled or ingested None in the quanty used here Precautions: Use gloves, safety glasses and lab coat during preparation and use.
Adjust the pH to 8 by adding boric acid or NaOH. Make up to 1 L with deionised water. Share, email or print. Sign up to join our network and access all content and features. If you already have an account, sign in , or connect with LinkedIn , Google. Premium accounts now available! Sign up now and claim your premium account. Read more here. This site uses cookies. Some cookies are essential to make the site work and others help us improve our services.
Essential - mandatory, cannot be disabled. Analytics - recommended, but not essential, can be disabled. Read more about cookies in our Privacy policy. Save Close. The borax may be anhydrous or in a pentahydrated or decahydrated form. The boric acid may be in an anhydrous boric oxide form or may be added as metaboric acid. During agitation of the moist mixture, the finer particles and the surface layer of the larger particles of the borax and boric acid are dissolved, forming sodium pentaborate 3 and agitation is continued with the particles in light rolling contact for a time interval sufficient for this sodium pentaborate phase to become associated With the remaining undissolved granules.
The solution of the surface of the larger particles is believed to smooth the sharp edges A more thorough understanding of the invention, its advantages and manner of operation and performance can be had from the following description of a typical preferred manner in which it can be carried out, it being understood that many changes may be made in the of these surfaces, a factor which otherwise contributes 5 specific detail of the described procedure and that equivato caking. The dissolution of the smaller particles obviouslent methods and materials may be used Without departly lliminates fines.
Generally, the mixing rate is mild and tumbling at below about 60 rpm, is sufiicient. Less than Laboratory scale experiments are conducted by placing two hours of mixing generally is satisfactory and d a mixture of borax or boric acid granules or the various tageously the product can be prepared in less than one q iv l n in a h ll of a laboratory r y x r pr hour of mixing, 15, vided with two lifters mounted at a slanting angle.
The manner of adding the ater can also influence the rotation Of the shell at 46 r. Stirring the particles durand mixed with a tumbling action. A predetermined ing water addition minimizes local agglomeration and quantity of Water is added gradually to the tumbling mixaddition of the water as a coarse or fine spray rather than ture as a coarse or fine stream from a wash bottle.
Tumlocally or instantaneously further avoids balling and 2 bling of the mixture is continued at ambient temperature lumping of the particles, and adherence of the mixture C. The water and the mixture are preferably at a moderate The mixture is then partially dried by contacting the temperature below 40 C.
Addition of ambient temperature water to flame until a desired temperature is attained. Mixing is an unheated mixture results in a slight rise in tempera- Continued until the product is cool. Lumps, if present, ture not requiring external cooling.
Amounts of water are removed with a 12 or 16 mesh screen and can be above about 12 percent may turn the mixture into a viscrushed and added to the product.
It has been found that optimum results are obgranules is demonstrated. The starting material consists tained with control of water between 5 to 10 percent. In of a mixture of grams of borax 5 mol, technical grade the absence of water, no sodium pentaborate is formed T. The storage. Six experiments are reported in the cessive drying time, and does not sufiiciently avoid caking. At temperatures of about C.
Temperatures between 90 and C. As heating is percent to 40 Percent by Weight of Water X ray crYStaL continued, some of the water will be evaporated and any lographic examination of the product of Experiment 1 bOIaX dewhydfate which y have formed 15 eliminated shows it to contain H BO and borax 5 mol, whereas the from the product. Heat is discontinued when the granules i ti f h products f h succeeding -iare sufficiently distinct to remain as stable, noncaking, ments, in which water was added, shows that they connonpowdering mixtures of sodium borate.
Minutes None 20 20 24 Temp. Type T. G- 12G. Amount, g Boric acid:. Type F. Amount, g 60 71 71 70 70 80 Time of addition, min 7 3 34 3. Minutes 21 33 Temp. Amount, g Minutes 22 20 19 Temp. Amount, g 0 74 70 Minutes 1 31 32 80 4 15 18 57 Temp. Minutes 11 10 15 20 17 13 Temp. The borax starting materials varied from the technical granular T.
The AB analysis is In some of the experiments the mixer is covered during a portion of the heating step. Caking tests are run by placing ml. The jar is placed in a cabinet which is cycled on a schedule of 12 hours at 75 F.
If not freefiowing FF , the material was tested with a penetrometer with a A" head and the readings were multiplied by 4. A zero reading indicates the material is not free-flowing but is penetrated by the penetrometer head with a pressure so slight as not to record a reading. A product showing a p. In experiments in which the water is added instantaneously from a graduate or in which the dry mixture is heated to above 40 C.
Drying at temperatures below 70 C. Consistently better results are apparent at temperatures from 90 C. It is necessary to add water at or near room temperature and to dry the prodnot at a high temperature.
It can also be seen from a comparison of Experiments 7 and 8 of Table II that substantially increased agitation time causes a more caked product.
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