SYNTHETIC AGGREGATES

• US 3,785,842 A
• Filed: 01/06/1971
• Issued: 01/15/1974
• Est. Priority Date: 01/16/1970
• Status: Expired due to Term

• Current Assignee: Ransome James Murray
• Original Assignee: Ransome James Murray
• Inventors: Murray, Ransome James
• Primary Examiner(s): Poer, James E.
• Application Number:
  US05/104,757
• Time in Patent Office: 1,105 Days
• Field of Search: 106/60,62,67,DIG.1,288B
• US Class Current: 106/457
• CPC Class Codes: C04B 35/01 based on oxide ceramics
• CPC Class Codes: C04B 35/12 based on chromium oxide C04B35/047 and C04B35/105 take precedence
• CPC Class Codes: C04B 35/16 based on silicates other than clay zircon C04B35/48
• CPC Class Codes: C04B 35/42 based on chromites C04B35/047 and C04B35/105 take precedence
• CPC Class Codes: C04B 35/44 based on aluminates

Abstract

A method of producing a synthetic aggregate, comprising preparing a finely divided raw material having an oxide analysis SiO2 5-35 percent, Al2O3 15-70 percent, FeO 0-65 percent. MgO 050 percent, alkalis <5 percent. and CaO<5 percent, the combined content of FeO and MgO being sufficient to provide at least 15 percent of spinels in the finished aggregate, agglomerating the raw material, and firing the agglomerated material at a temperature causing recrystallization of the raw materials until substantial elimination of any uncombined magnesium oxide is achieved and a material is produced comprising spinel crystals imbedded in a matrix of alumino-silicates, silicates, or a mixture thereof, and having a porosity low enough to provide an aggregate abrasion value less than 20 percent.

Claims

2. A method according to claim 1 wherein the Al2O3 is in the range 15-40 percent, the FeO content in the range 5-40 percent, the MgO content in the range 5-40 percent, and the combined content of FeO and MgO is sufficient to produce at least 25 percent of spinels in the aggregate produced.

3. A method according to claim 2, in which at least a proportion of the iron content of the raw material is in ferric form, and the firing step is carried out under reducing conditions.

4. A method according to claim 2, wherein the raw material is a high iron clay.

5. The method of claim 2 wherein the single firing is performed at a first and second temperature.

6. An Improved road stone synthetic aggregate having a highskid resistant surface while being economical to produce having a content as follows:

SiO2 - 5-35 percent, Al2O3 - 15-70 percent, FeO - 0-65 percent, MgO - 0-50 percent, alkalis <

5 percent, CaO <

5 percent;

at least 15 percent of said content being in spinel crystal form, said spinel being in a matrix of silicates and said aggregate having an aggregate abrasion value of less than 20 percent, and a polished stone value of at least 60.

7. The road stone synthetic aggregate of claim 6 wherein at least 25 percent of said content is in spinel form.